ActiveRecord::Base#assign_multiparameter_attributes

/app/.bundle/gems/gems/activerecord-3.0.0.beta/lib/active_record/base.rb:2269
   1 require 'yaml'
   2 require 'set'
   3 require 'active_support/benchmarkable'
   4 require 'active_support/dependencies'
   5 require 'active_support/time'
   6 require 'active_support/core_ext/class/attribute_accessors'
   7 require 'active_support/core_ext/class/delegating_attributes'
   8 require 'active_support/core_ext/class/inheritable_attributes'
   9 require 'active_support/core_ext/array/extract_options'
  10 require 'active_support/core_ext/hash/deep_merge'
  11 require 'active_support/core_ext/hash/indifferent_access'
  12 require 'active_support/core_ext/hash/slice'
  13 require 'active_support/core_ext/string/behavior'
  14 require 'active_support/core_ext/object/metaclass'
  15 require 'active_support/core_ext/module/delegation'
  16 
  17 module ActiveRecord #:nodoc:
  18   # Generic Active Record exception class.
  19   class ActiveRecordError < StandardError
  20   end
  21 
  22   # Raised when the single-table inheritance mechanism fails to locate the subclass
  23   # (for example due to improper usage of column that +inheritance_column+ points to).
  24   class SubclassNotFound < ActiveRecordError #:nodoc:
  25   end
  26 
  27   # Raised when an object assigned to an association has an incorrect type.
  28   #
  29   #   class Ticket < ActiveRecord::Base
  30   #     has_many :patches
  31   #   end
  32   #
  33   #   class Patch < ActiveRecord::Base
  34   #     belongs_to :ticket
  35   #   end
  36   #
  37   #   # Comments are not patches, this assignment raises AssociationTypeMismatch.
  38   #   @ticket.patches << Comment.new(:content => "Please attach tests to your patch.")
  39   class AssociationTypeMismatch < ActiveRecordError
  40   end
  41 
  42   # Raised when unserialized object's type mismatches one specified for serializable field.
  43   class SerializationTypeMismatch < ActiveRecordError
  44   end
  45 
  46   # Raised when adapter not specified on connection (or configuration file <tt>config/database.yml</tt> misses adapter field).
  47   class AdapterNotSpecified < ActiveRecordError
  48   end
  49 
  50   # Raised when Active Record cannot find database adapter specified in <tt>config/database.yml</tt> or programmatically.
  51   class AdapterNotFound < ActiveRecordError
  52   end
  53 
  54   # Raised when connection to the database could not been established (for example when <tt>connection=</tt> is given a nil object).
  55   class ConnectionNotEstablished < ActiveRecordError
  56   end
  57 
  58   # Raised when Active Record cannot find record by given id or set of ids.
  59   class RecordNotFound < ActiveRecordError
  60   end
  61 
  62   # Raised by ActiveRecord::Base.save! and ActiveRecord::Base.create! methods when record cannot be
  63   # saved because record is invalid.
  64   class RecordNotSaved < ActiveRecordError
  65   end
  66 
  67   # Raised when SQL statement cannot be executed by the database (for example, it's often the case for MySQL when Ruby driver used is too old).
  68   class StatementInvalid < ActiveRecordError
  69   end
  70 
  71   # Raised when SQL statement is invalid and the application gets a blank result.
  72   class ThrowResult < ActiveRecordError
  73   end
  74 
  75   # Parent class for all specific exceptions which wrap database driver exceptions
  76   # provides access to the original exception also.
  77   class WrappedDatabaseException < StatementInvalid
  78     attr_reader :original_exception
  79 
  80     def initialize(message, original_exception)
  81       super(message)
  82       @original_exception = original_exception
  83     end
  84   end
  85 
  86   # Raised when a record cannot be inserted because it would violate a uniqueness constraint.
  87   class RecordNotUnique < WrappedDatabaseException
  88   end
  89 
  90   # Raised when a record cannot be inserted or updated because it references a non-existent record.
  91   class InvalidForeignKey < WrappedDatabaseException
  92   end
  93 
  94   # Raised when number of bind variables in statement given to <tt>:condition</tt> key (for example, when using +find+ method)
  95   # does not match number of expected variables.
  96   #
  97   # For example, in
  98   #
  99   #   Location.find :all, :conditions => ["lat = ? AND lng = ?", 53.7362]
 100   #
 101   # two placeholders are given but only one variable to fill them.
 102   class PreparedStatementInvalid < ActiveRecordError
 103   end
 104 
 105   # Raised on attempt to save stale record. Record is stale when it's being saved in another query after
 106   # instantiation, for example, when two users edit the same wiki page and one starts editing and saves
 107   # the page before the other.
 108   #
 109   # Read more about optimistic locking in ActiveRecord::Locking module RDoc.
 110   class StaleObjectError < ActiveRecordError
 111   end
 112 
 113   # Raised when association is being configured improperly or
 114   # user tries to use offset and limit together with has_many or has_and_belongs_to_many associations.
 115   class ConfigurationError < ActiveRecordError
 116   end
 117 
 118   # Raised on attempt to update record that is instantiated as read only.
 119   class ReadOnlyRecord < ActiveRecordError
 120   end
 121 
 122   # ActiveRecord::Transactions::ClassMethods.transaction uses this exception
 123   # to distinguish a deliberate rollback from other exceptional situations.
 124   # Normally, raising an exception will cause the +transaction+ method to rollback
 125   # the database transaction *and* pass on the exception. But if you raise an
 126   # ActiveRecord::Rollback exception, then the database transaction will be rolled back,
 127   # without passing on the exception.
 128   #
 129   # For example, you could do this in your controller to rollback a transaction:
 130   #
 131   #   class BooksController < ActionController::Base
 132   #     def create
 133   #       Book.transaction do
 134   #         book = Book.new(params[:book])
 135   #         book.save!
 136   #         if today_is_friday?
 137   #           # The system must fail on Friday so that our support department
 138   #           # won't be out of job. We silently rollback this transaction
 139   #           # without telling the user.
 140   #           raise ActiveRecord::Rollback, "Call tech support!"
 141   #         end
 142   #       end
 143   #       # ActiveRecord::Rollback is the only exception that won't be passed on
 144   #       # by ActiveRecord::Base.transaction, so this line will still be reached
 145   #       # even on Friday.
 146   #       redirect_to root_url
 147   #     end
 148   #   end
 149   class Rollback < ActiveRecordError
 150   end
 151 
 152   # Raised when attribute has a name reserved by Active Record (when attribute has name of one of Active Record instance methods).
 153   class DangerousAttributeError < ActiveRecordError
 154   end
 155 
 156   # Raised when unknown attributes are supplied via mass assignment.
 157   class UnknownAttributeError < NoMethodError
 158   end
 159 
 160   # Raised when an error occurred while doing a mass assignment to an attribute through the
 161   # <tt>attributes=</tt> method. The exception has an +attribute+ property that is the name of the
 162   # offending attribute.
 163   class AttributeAssignmentError < ActiveRecordError
 164     attr_reader :exception, :attribute
 165     def initialize(message, exception, attribute)
 166       @exception = exception
 167       @attribute = attribute
 168       @message = message
 169     end
 170   end
 171 
 172   # Raised when there are multiple errors while doing a mass assignment through the +attributes+
 173   # method. The exception has an +errors+ property that contains an array of AttributeAssignmentError
 174   # objects, each corresponding to the error while assigning to an attribute.
 175   class MultiparameterAssignmentErrors < ActiveRecordError
 176     attr_reader :errors
 177     def initialize(errors)
 178       @errors = errors
 179     end
 180   end
 181 
 182   # Active Record objects don't specify their attributes directly, but rather infer them from the table definition with
 183   # which they're linked. Adding, removing, and changing attributes and their type is done directly in the database. Any change
 184   # is instantly reflected in the Active Record objects. The mapping that binds a given Active Record class to a certain
 185   # database table will happen automatically in most common cases, but can be overwritten for the uncommon ones.
 186   #
 187   # See the mapping rules in table_name and the full example in link:files/README.html for more insight.
 188   #
 189   # == Creation
 190   #
 191   # Active Records accept constructor parameters either in a hash or as a block. The hash method is especially useful when
 192   # you're receiving the data from somewhere else, like an HTTP request. It works like this:
 193   #
 194   #   user = User.new(:name => "David", :occupation => "Code Artist")
 195   #   user.name # => "David"
 196   #
 197   # You can also use block initialization:
 198   #
 199   #   user = User.new do |u|
 200   #     u.name = "David"
 201   #     u.occupation = "Code Artist"
 202   #   end
 203   #
 204   # And of course you can just create a bare object and specify the attributes after the fact:
 205   #
 206   #   user = User.new
 207   #   user.name = "David"
 208   #   user.occupation = "Code Artist"
 209   #
 210   # == Conditions
 211   #
 212   # Conditions can either be specified as a string, array, or hash representing the WHERE-part of an SQL statement.
 213   # The array form is to be used when the condition input is tainted and requires sanitization. The string form can
 214   # be used for statements that don't involve tainted data. The hash form works much like the array form, except
 215   # only equality and range is possible. Examples:
 216   #
 217   #   class User < ActiveRecord::Base
 218   #     def self.authenticate_unsafely(user_name, password)
 219   #       find(:first, :conditions => "user_name = '#{user_name}' AND password = '#{password}'")
 220   #     end
 221   #
 222   #     def self.authenticate_safely(user_name, password)
 223   #       find(:first, :conditions => [ "user_name = ? AND password = ?", user_name, password ])
 224   #     end
 225   #
 226   #     def self.authenticate_safely_simply(user_name, password)
 227   #       find(:first, :conditions => { :user_name => user_name, :password => password })
 228   #     end
 229   #   end
 230   #
 231   # The <tt>authenticate_unsafely</tt> method inserts the parameters directly into the query and is thus susceptible to SQL-injection
 232   # attacks if the <tt>user_name</tt> and +password+ parameters come directly from an HTTP request. The <tt>authenticate_safely</tt>  and
 233   # <tt>authenticate_safely_simply</tt> both will sanitize the <tt>user_name</tt> and +password+ before inserting them in the query,
 234   # which will ensure that an attacker can't escape the query and fake the login (or worse).
 235   #
 236   # When using multiple parameters in the conditions, it can easily become hard to read exactly what the fourth or fifth
 237   # question mark is supposed to represent. In those cases, you can resort to named bind variables instead. That's done by replacing
 238   # the question marks with symbols and supplying a hash with values for the matching symbol keys:
 239   #
 240   #   Company.find(:first, :conditions => [
 241   #     "id = :id AND name = :name AND division = :division AND created_at > :accounting_date",
 242   #     { :id => 3, :name => "37signals", :division => "First", :accounting_date => '2005-01-01' }
 243   #   ])
 244   #
 245   # Similarly, a simple hash without a statement will generate conditions based on equality with the SQL AND
 246   # operator. For instance:
 247   #
 248   #   Student.find(:all, :conditions => { :first_name => "Harvey", :status => 1 })
 249   #   Student.find(:all, :conditions => params[:student])
 250   #
 251   # A range may be used in the hash to use the SQL BETWEEN operator:
 252   #
 253   #   Student.find(:all, :conditions => { :grade => 9..12 })
 254   #
 255   # An array may be used in the hash to use the SQL IN operator:
 256   #
 257   #   Student.find(:all, :conditions => { :grade => [9,11,12] })
 258   #
 259   # When joining tables, nested hashes or keys written in the form 'table_name.column_name' can be used to qualify the table name of a
 260   # particular condition. For instance:
 261   #
 262   #   Student.find(:all, :conditions => { :schools => { :type => 'public' }}, :joins => :schools)
 263   #   Student.find(:all, :conditions => { 'schools.type' => 'public' }, :joins => :schools)
 264   #
 265   # == Overwriting default accessors
 266   #
 267   # All column values are automatically available through basic accessors on the Active Record object, but sometimes you
 268   # want to specialize this behavior. This can be done by overwriting the default accessors (using the same
 269   # name as the attribute) and calling <tt>read_attribute(attr_name)</tt> and <tt>write_attribute(attr_name, value)</tt> to actually change things.
 270   # Example:
 271   #
 272   #   class Song < ActiveRecord::Base
 273   #     # Uses an integer of seconds to hold the length of the song
 274   #
 275   #     def length=(minutes)
 276   #       write_attribute(:length, minutes.to_i * 60)
 277   #     end
 278   #
 279   #     def length
 280   #       read_attribute(:length) / 60
 281   #     end
 282   #   end
 283   #
 284   # You can alternatively use <tt>self[:attribute]=(value)</tt> and <tt>self[:attribute]</tt> instead of <tt>write_attribute(:attribute, value)</tt> and
 285   # <tt>read_attribute(:attribute)</tt> as a shorter form.
 286   #
 287   # == Attribute query methods
 288   #
 289   # In addition to the basic accessors, query methods are also automatically available on the Active Record object.
 290   # Query methods allow you to test whether an attribute value is present.
 291   #
 292   # For example, an Active Record User with the <tt>name</tt> attribute has a <tt>name?</tt> method that you can call
 293   # to determine whether the user has a name:
 294   #
 295   #   user = User.new(:name => "David")
 296   #   user.name? # => true
 297   #
 298   #   anonymous = User.new(:name => "")
 299   #   anonymous.name? # => false
 300   #
 301   # == Accessing attributes before they have been typecasted
 302   #
 303   # Sometimes you want to be able to read the raw attribute data without having the column-determined typecast run its course first.
 304   # That can be done by using the <tt><attribute>_before_type_cast</tt> accessors that all attributes have. For example, if your Account model
 305   # has a <tt>balance</tt> attribute, you can call <tt>account.balance_before_type_cast</tt> or <tt>account.id_before_type_cast</tt>.
 306   #
 307   # This is especially useful in validation situations where the user might supply a string for an integer field and you want to display
 308   # the original string back in an error message. Accessing the attribute normally would typecast the string to 0, which isn't what you
 309   # want.
 310   #
 311   # == Dynamic attribute-based finders
 312   #
 313   # Dynamic attribute-based finders are a cleaner way of getting (and/or creating) objects by simple queries without turning to SQL. They work by
 314   # appending the name of an attribute to <tt>find_by_</tt>, <tt>find_last_by_</tt>, or <tt>find_all_by_</tt>, so you get finders like <tt>Person.find_by_user_name</tt>,
 315   # <tt>Person.find_all_by_last_name</tt>, and <tt>Payment.find_by_transaction_id</tt>. So instead of writing
 316   # <tt>Person.find(:first, :conditions => ["user_name = ?", user_name])</tt>, you just do <tt>Person.find_by_user_name(user_name)</tt>.
 317   # And instead of writing <tt>Person.find(:all, :conditions => ["last_name = ?", last_name])</tt>, you just do <tt>Person.find_all_by_last_name(last_name)</tt>.
 318   #
 319   # It's also possible to use multiple attributes in the same find by separating them with "_and_", so you get finders like
 320   # <tt>Person.find_by_user_name_and_password</tt> or even <tt>Payment.find_by_purchaser_and_state_and_country</tt>. So instead of writing
 321   # <tt>Person.find(:first, :conditions => ["user_name = ? AND password = ?", user_name, password])</tt>, you just do
 322   # <tt>Person.find_by_user_name_and_password(user_name, password)</tt>.
 323   #
 324   # It's even possible to use all the additional parameters to find. For example, the full interface for <tt>Payment.find_all_by_amount</tt>
 325   # is actually <tt>Payment.find_all_by_amount(amount, options)</tt>. And the full interface to <tt>Person.find_by_user_name</tt> is
 326   # actually <tt>Person.find_by_user_name(user_name, options)</tt>. So you could call <tt>Payment.find_all_by_amount(50, :order => "created_on")</tt>.
 327   # Also you may call <tt>Payment.find_last_by_amount(amount, options)</tt> returning the last record matching that amount and options.
 328   #
 329   # The same dynamic finder style can be used to create the object if it doesn't already exist. This dynamic finder is called with
 330   # <tt>find_or_create_by_</tt> and will return the object if it already exists and otherwise creates it, then returns it. Protected attributes won't be set unless they are given in a block. For example:
 331   #
 332   #   # No 'Summer' tag exists
 333   #   Tag.find_or_create_by_name("Summer") # equal to Tag.create(:name => "Summer")
 334   #
 335   #   # Now the 'Summer' tag does exist
 336   #   Tag.find_or_create_by_name("Summer") # equal to Tag.find_by_name("Summer")
 337   #
 338   #   # Now 'Bob' exist and is an 'admin'
 339   #   User.find_or_create_by_name('Bob', :age => 40) { |u| u.admin = true }
 340   #
 341   # Use the <tt>find_or_initialize_by_</tt> finder if you want to return a new record without saving it first. Protected attributes won't be set unless they are given in a block. For example:
 342   #
 343   #   # No 'Winter' tag exists
 344   #   winter = Tag.find_or_initialize_by_name("Winter")
 345   #   winter.new_record? # true
 346   #
 347   # To find by a subset of the attributes to be used for instantiating a new object, pass a hash instead of
 348   # a list of parameters. For example:
 349   #
 350   #   Tag.find_or_create_by_name(:name => "rails", :creator => current_user)
 351   #
 352   # That will either find an existing tag named "rails", or create a new one while setting the user that created it.
 353   #
 354   # == Saving arrays, hashes, and other non-mappable objects in text columns
 355   #
 356   # Active Record can serialize any object in text columns using YAML. To do so, you must specify this with a call to the class method +serialize+.
 357   # This makes it possible to store arrays, hashes, and other non-mappable objects without doing any additional work. Example:
 358   #
 359   #   class User < ActiveRecord::Base
 360   #     serialize :preferences
 361   #   end
 362   #
 363   #   user = User.create(:preferences => { "background" => "black", "display" => large })
 364   #   User.find(user.id).preferences # => { "background" => "black", "display" => large }
 365   #
 366   # You can also specify a class option as the second parameter that'll raise an exception if a serialized object is retrieved as a
 367   # descendant of a class not in the hierarchy. Example:
 368   #
 369   #   class User < ActiveRecord::Base
 370   #     serialize :preferences, Hash
 371   #   end
 372   #
 373   #   user = User.create(:preferences => %w( one two three ))
 374   #   User.find(user.id).preferences    # raises SerializationTypeMismatch
 375   #
 376   # == Single table inheritance
 377   #
 378   # Active Record allows inheritance by storing the name of the class in a column that by default is named "type" (can be changed
 379   # by overwriting <tt>Base.inheritance_column</tt>). This means that an inheritance looking like this:
 380   #
 381   #   class Company < ActiveRecord::Base; end
 382   #   class Firm < Company; end
 383   #   class Client < Company; end
 384   #   class PriorityClient < Client; end
 385   #
 386   # When you do <tt>Firm.create(:name => "37signals")</tt>, this record will be saved in the companies table with type = "Firm". You can then
 387   # fetch this row again using <tt>Company.find(:first, "name = '37signals'")</tt> and it will return a Firm object.
 388   #
 389   # If you don't have a type column defined in your table, single-table inheritance won't be triggered. In that case, it'll work just
 390   # like normal subclasses with no special magic for differentiating between them or reloading the right type with find.
 391   #
 392   # Note, all the attributes for all the cases are kept in the same table. Read more:
 393   # http://www.martinfowler.com/eaaCatalog/singleTableInheritance.html
 394   #
 395   # == Connection to multiple databases in different models
 396   #
 397   # Connections are usually created through ActiveRecord::Base.establish_connection and retrieved by ActiveRecord::Base.connection.
 398   # All classes inheriting from ActiveRecord::Base will use this connection. But you can also set a class-specific connection.
 399   # For example, if Course is an ActiveRecord::Base, but resides in a different database, you can just say <tt>Course.establish_connection</tt>
 400   # and Course and all of its subclasses will use this connection instead.
 401   #
 402   # This feature is implemented by keeping a connection pool in ActiveRecord::Base that is a Hash indexed by the class. If a connection is
 403   # requested, the retrieve_connection method will go up the class-hierarchy until a connection is found in the connection pool.
 404   #
 405   # == Exceptions
 406   #
 407   # * ActiveRecordError - Generic error class and superclass of all other errors raised by Active Record.
 408   # * AdapterNotSpecified - The configuration hash used in <tt>establish_connection</tt> didn't include an
 409   #   <tt>:adapter</tt> key.
 410   # * AdapterNotFound - The <tt>:adapter</tt> key used in <tt>establish_connection</tt> specified a non-existent adapter
 411   #   (or a bad spelling of an existing one).
 412   # * AssociationTypeMismatch - The object assigned to the association wasn't of the type specified in the association definition.
 413   # * SerializationTypeMismatch - The serialized object wasn't of the class specified as the second parameter.
 414   # * ConnectionNotEstablished+ - No connection has been established. Use <tt>establish_connection</tt> before querying.
 415   # * RecordNotFound - No record responded to the +find+ method. Either the row with the given ID doesn't exist
 416   #   or the row didn't meet the additional restrictions. Some +find+ calls do not raise this exception to signal
 417   #   nothing was found, please check its documentation for further details.
 418   # * StatementInvalid - The database server rejected the SQL statement. The precise error is added in the message.
 419   # * MultiparameterAssignmentErrors - Collection of errors that occurred during a mass assignment using the
 420   #   <tt>attributes=</tt> method. The +errors+ property of this exception contains an array of AttributeAssignmentError
 421   #   objects that should be inspected to determine which attributes triggered the errors.
 422   # * AttributeAssignmentError - An error occurred while doing a mass assignment through the <tt>attributes=</tt> method.
 423   #   You can inspect the +attribute+ property of the exception object to determine which attribute triggered the error.
 424   #
 425   # *Note*: The attributes listed are class-level attributes (accessible from both the class and instance level).
 426   # So it's possible to assign a logger to the class through <tt>Base.logger=</tt> which will then be used by all
 427   # instances in the current object space.
 428   class Base
 429     ##
 430     # :singleton-method:
 431     # Accepts a logger conforming to the interface of Log4r or the default Ruby 1.8+ Logger class, which is then passed
 432     # on to any new database connections made and which can be retrieved on both a class and instance level by calling +logger+.
 433     cattr_accessor :logger, :instance_writer => false
 434 
 435     def self.inherited(child) #:nodoc:
 436       @@subclasses[self] ||= []
 437       @@subclasses[self] << child
 438       super
 439     end
 440 
 441     def self.reset_subclasses #:nodoc:
 442       nonreloadables = []
 443       subclasses.each do |klass|
 444         unless ActiveSupport::Dependencies.autoloaded? klass
 445           nonreloadables << klass
 446           next
 447         end
 448         klass.instance_variables.each { |var| klass.send(:remove_instance_variable, var) }
 449         klass.instance_methods(false).each { |m| klass.send :undef_method, m }
 450       end
 451       @@subclasses = {}
 452       nonreloadables.each { |klass| (@@subclasses[klass.superclass] ||= []) << klass }
 453     end
 454 
 455     @@subclasses = {}
 456 
 457     ##
 458     # :singleton-method:
 459     # Contains the database configuration - as is typically stored in config/database.yml -
 460     # as a Hash.
 461     #
 462     # For example, the following database.yml...
 463     #
 464     #   development:
 465     #     adapter: sqlite3
 466     #     database: db/development.sqlite3
 467     #
 468     #   production:
 469     #     adapter: sqlite3
 470     #     database: db/production.sqlite3
 471     #
 472     # ...would result in ActiveRecord::Base.configurations to look like this:
 473     #
 474     #   {
 475     #      'development' => {
 476     #         'adapter'  => 'sqlite3',
 477     #         'database' => 'db/development.sqlite3'
 478     #      },
 479     #      'production' => {
 480     #         'adapter'  => 'sqlite3',
 481     #         'database' => 'db/production.sqlite3'
 482     #      }
 483     #   }
 484     cattr_accessor :configurations, :instance_writer => false
 485     @@configurations = {}
 486 
 487     ##
 488     # :singleton-method:
 489     # Accessor for the prefix type that will be prepended to every primary key column name. The options are :table_name and
 490     # :table_name_with_underscore. If the first is specified, the Product class will look for "productid" instead of "id" as
 491     # the primary column. If the latter is specified, the Product class will look for "product_id" instead of "id". Remember
 492     # that this is a global setting for all Active Records.
 493     cattr_accessor :primary_key_prefix_type, :instance_writer => false
 494     @@primary_key_prefix_type = nil
 495 
 496     ##
 497     # :singleton-method:
 498     # Accessor for the name of the prefix string to prepend to every table name. So if set to "basecamp_", all
 499     # table names will be named like "basecamp_projects", "basecamp_people", etc. This is a convenient way of creating a namespace
 500     # for tables in a shared database. By default, the prefix is the empty string.
 501     cattr_accessor :table_name_prefix, :instance_writer => false
 502     @@table_name_prefix = ""
 503 
 504     ##
 505     # :singleton-method:
 506     # Works like +table_name_prefix+, but appends instead of prepends (set to "_basecamp" gives "projects_basecamp",
 507     # "people_basecamp"). By default, the suffix is the empty string.
 508     cattr_accessor :table_name_suffix, :instance_writer => false
 509     @@table_name_suffix = ""
 510 
 511     ##
 512     # :singleton-method:
 513     # Indicates whether table names should be the pluralized versions of the corresponding class names.
 514     # If true, the default table name for a Product class will be +products+. If false, it would just be +product+.
 515     # See table_name for the full rules on table/class naming. This is true, by default.
 516     cattr_accessor :pluralize_table_names, :instance_writer => false
 517     @@pluralize_table_names = true
 518 
 519     ##
 520     # :singleton-method:
 521     # Determines whether to use Time.local (using :local) or Time.utc (using :utc) when pulling dates and times from the database.
 522     # This is set to :local by default.
 523     cattr_accessor :default_timezone, :instance_writer => false
 524     @@default_timezone = :local
 525 
 526     ##
 527     # :singleton-method:
 528     # Specifies the format to use when dumping the database schema with Rails'
 529     # Rakefile.  If :sql, the schema is dumped as (potentially database-
 530     # specific) SQL statements.  If :ruby, the schema is dumped as an
 531     # ActiveRecord::Schema file which can be loaded into any database that
 532     # supports migrations.  Use :ruby if you want to have different database
 533     # adapters for, e.g., your development and test environments.
 534     cattr_accessor :schema_format , :instance_writer => false
 535     @@schema_format = :ruby
 536 
 537     ##
 538     # :singleton-method:
 539     # Specify whether or not to use timestamps for migration numbers
 540     cattr_accessor :timestamped_migrations , :instance_writer => false
 541     @@timestamped_migrations = true
 542 
 543     # Determine whether to store the full constant name including namespace when using STI
 544     superclass_delegating_accessor :store_full_sti_class
 545     self.store_full_sti_class = true
 546 
 547     # Stores the default scope for the class
 548     class_inheritable_accessor :default_scoping, :instance_writer => false
 549     self.default_scoping = []
 550 
 551     class << self # Class methods
 552       def colorize_logging(*args)
 553         ActiveSupport::Deprecation.warn "ActiveRecord::Base.colorize_logging and " <<
 554           "config.active_record.colorize_logging are deprecated. Please use " << 
 555           "Rails::Subscriber.colorize_logging or config.colorize_logging instead", caller
 556       end
 557       alias :colorize_logging= :colorize_logging
 558 
 559       delegate :find, :first, :last, :all, :destroy, :destroy_all, :exists?, :delete, :delete_all, :update, :update_all, :to => :scoped
 560       delegate :select, :group, :order, :limit, :joins, :where, :preload, :eager_load, :includes, :from, :lock, :readonly, :having, :to => :scoped
 561       delegate :count, :average, :minimum, :maximum, :sum, :calculate, :to => :scoped
 562 
 563       # Executes a custom SQL query against your database and returns all the results.  The results will
 564       # be returned as an array with columns requested encapsulated as attributes of the model you call
 565       # this method from.  If you call <tt>Product.find_by_sql</tt> then the results will be returned in
 566       # a Product object with the attributes you specified in the SQL query.
 567       #
 568       # If you call a complicated SQL query which spans multiple tables the columns specified by the
 569       # SELECT will be attributes of the model, whether or not they are columns of the corresponding
 570       # table.
 571       #
 572       # The +sql+ parameter is a full SQL query as a string.  It will be called as is, there will be
 573       # no database agnostic conversions performed.  This should be a last resort because using, for example,
 574       # MySQL specific terms will lock you to using that particular database engine or require you to
 575       # change your call if you switch engines.
 576       #
 577       # ==== Examples
 578       #   # A simple SQL query spanning multiple tables
 579       #   Post.find_by_sql "SELECT p.title, c.author FROM posts p, comments c WHERE p.id = c.post_id"
 580       #   > [#<Post:0x36bff9c @attributes={"title"=>"Ruby Meetup", "first_name"=>"Quentin"}>, ...]
 581       #
 582       #   # You can use the same string replacement techniques as you can with ActiveRecord#find
 583       #   Post.find_by_sql ["SELECT title FROM posts WHERE author = ? AND created > ?", author_id, start_date]
 584       #   > [#<Post:0x36bff9c @attributes={"first_name"=>"The Cheap Man Buys Twice"}>, ...]
 585       def find_by_sql(sql)
 586         connection.select_all(sanitize_sql(sql), "#{name} Load").collect! { |record| instantiate(record) }
 587       end
 588 
 589       # Creates an object (or multiple objects) and saves it to the database, if validations pass.
 590       # The resulting object is returned whether the object was saved successfully to the database or not.
 591       #
 592       # The +attributes+ parameter can be either be a Hash or an Array of Hashes.  These Hashes describe the
 593       # attributes on the objects that are to be created.
 594       #
 595       # ==== Examples
 596       #   # Create a single new object
 597       #   User.create(:first_name => 'Jamie')
 598       #
 599       #   # Create an Array of new objects
 600       #   User.create([{ :first_name => 'Jamie' }, { :first_name => 'Jeremy' }])
 601       #
 602       #   # Create a single object and pass it into a block to set other attributes.
 603       #   User.create(:first_name => 'Jamie') do |u|
 604       #     u.is_admin = false
 605       #   end
 606       #
 607       #   # Creating an Array of new objects using a block, where the block is executed for each object:
 608       #   User.create([{ :first_name => 'Jamie' }, { :first_name => 'Jeremy' }]) do |u|
 609       #     u.is_admin = false
 610       #   end
 611       def create(attributes = nil, &block)
 612         if attributes.is_a?(Array)
 613           attributes.collect { |attr| create(attr, &block) }
 614         else
 615           object = new(attributes)
 616           yield(object) if block_given?
 617           object.save
 618           object
 619         end
 620       end
 621 
 622       # Returns the result of an SQL statement that should only include a COUNT(*) in the SELECT part.
 623       # The use of this method should be restricted to complicated SQL queries that can't be executed
 624       # using the ActiveRecord::Calculations class methods.  Look into those before using this.
 625       #
 626       # ==== Parameters
 627       #
 628       # * +sql+ - An SQL statement which should return a count query from the database, see the example below.
 629       #
 630       # ==== Examples
 631       #
 632       #   Product.count_by_sql "SELECT COUNT(*) FROM sales s, customers c WHERE s.customer_id = c.id"
 633       def count_by_sql(sql)
 634         sql = sanitize_conditions(sql)
 635         connection.select_value(sql, "#{name} Count").to_i
 636       end
 637 
 638       # Resets one or more counter caches to their correct value using an SQL
 639       # count query.  This is useful when adding new counter caches, or if the
 640       # counter has been corrupted or modified directly by SQL.
 641       #
 642       # ==== Parameters
 643       #
 644       # * +id+ - The id of the object you wish to reset a counter on.
 645       # * +counters+ - One or more counter names to reset
 646       #
 647       # ==== Examples
 648       #
 649       #   # For Post with id #1 records reset the comments_count
 650       #   Post.reset_counters(1, :comments)
 651       def reset_counters(id, *counters)
 652         object = find(id)
 653         counters.each do |association|
 654           child_class = reflect_on_association(association).klass
 655           counter_name = child_class.reflect_on_association(self.name.downcase.to_sym).counter_cache_column
 656 
 657           connection.update("UPDATE #{quoted_table_name} SET #{connection.quote_column_name(counter_name)} = #{object.send(association).count} WHERE #{connection.quote_column_name(primary_key)} = #{quote_value(object.id)}", "#{name} UPDATE")
 658         end
 659       end
 660 
 661       # A generic "counter updater" implementation, intended primarily to be
 662       # used by increment_counter and decrement_counter, but which may also
 663       # be useful on its own. It simply does a direct SQL update for the record
 664       # with the given ID, altering the given hash of counters by the amount
 665       # given by the corresponding value:
 666       #
 667       # ==== Parameters
 668       #
 669       # * +id+ - The id of the object you wish to update a counter on or an Array of ids.
 670       # * +counters+ - An Array of Hashes containing the names of the fields
 671       #   to update as keys and the amount to update the field by as values.
 672       #
 673       # ==== Examples
 674       #
 675       #   # For the Post with id of 5, decrement the comment_count by 1, and
 676       #   # increment the action_count by 1
 677       #   Post.update_counters 5, :comment_count => -1, :action_count => 1
 678       #   # Executes the following SQL:
 679       #   # UPDATE posts
 680       #   #    SET comment_count = comment_count - 1,
 681       #   #        action_count = action_count + 1
 682       #   #  WHERE id = 5
 683       #
 684       #   # For the Posts with id of 10 and 15, increment the comment_count by 1
 685       #   Post.update_counters [10, 15], :comment_count => 1
 686       #   # Executes the following SQL:
 687       #   # UPDATE posts
 688       #   #    SET comment_count = comment_count + 1,
 689       #   #  WHERE id IN (10, 15)
 690       def update_counters(id, counters)
 691         updates = counters.inject([]) { |list, (counter_name, increment)|
 692           sign = increment < 0 ? "-" : "+"
 693           list << "#{connection.quote_column_name(counter_name)} = COALESCE(#{connection.quote_column_name(counter_name)}, 0) #{sign} #{increment.abs}"
 694         }.join(", ")
 695 
 696         if id.is_a?(Array)
 697           ids_list = id.map {|i| quote_value(i)}.join(', ')
 698           condition = "IN  (#{ids_list})"
 699         else
 700           condition = "= #{quote_value(id)}"
 701         end
 702 
 703         update_all(updates, "#{connection.quote_column_name(primary_key)} #{condition}")
 704       end
 705 
 706       # Increment a number field by one, usually representing a count.
 707       #
 708       # This is used for caching aggregate values, so that they don't need to be computed every time.
 709       # For example, a DiscussionBoard may cache post_count and comment_count otherwise every time the board is
 710       # shown it would have to run an SQL query to find how many posts and comments there are.
 711       #
 712       # ==== Parameters
 713       #
 714       # * +counter_name+ - The name of the field that should be incremented.
 715       # * +id+ - The id of the object that should be incremented.
 716       #
 717       # ==== Examples
 718       #
 719       #   # Increment the post_count column for the record with an id of 5
 720       #   DiscussionBoard.increment_counter(:post_count, 5)
 721       def increment_counter(counter_name, id)
 722         update_counters(id, counter_name => 1)
 723       end
 724 
 725       # Decrement a number field by one, usually representing a count.
 726       #
 727       # This works the same as increment_counter but reduces the column value by 1 instead of increasing it.
 728       #
 729       # ==== Parameters
 730       #
 731       # * +counter_name+ - The name of the field that should be decremented.
 732       # * +id+ - The id of the object that should be decremented.
 733       #
 734       # ==== Examples
 735       #
 736       #   # Decrement the post_count column for the record with an id of 5
 737       #   DiscussionBoard.decrement_counter(:post_count, 5)
 738       def decrement_counter(counter_name, id)
 739         update_counters(id, counter_name => -1)
 740       end
 741 
 742       # Attributes named in this macro are protected from mass-assignment,
 743       # such as <tt>new(attributes)</tt>,
 744       # <tt>update_attributes(attributes)</tt>, or
 745       # <tt>attributes=(attributes)</tt>.
 746       #
 747       # Mass-assignment to these attributes will simply be ignored, to assign
 748       # to them you can use direct writer methods. This is meant to protect
 749       # sensitive attributes from being overwritten by malicious users
 750       # tampering with URLs or forms.
 751       #
 752       #   class Customer < ActiveRecord::Base
 753       #     attr_protected :credit_rating
 754       #   end
 755       #
 756       #   customer = Customer.new("name" => David, "credit_rating" => "Excellent")
 757       #   customer.credit_rating # => nil
 758       #   customer.attributes = { "description" => "Jolly fellow", "credit_rating" => "Superb" }
 759       #   customer.credit_rating # => nil
 760       #
 761       #   customer.credit_rating = "Average"
 762       #   customer.credit_rating # => "Average"
 763       #
 764       # To start from an all-closed default and enable attributes as needed,
 765       # have a look at +attr_accessible+.
 766       #
 767       # If the access logic of your application is richer you can use <tt>Hash#except</tt>
 768       # or <tt>Hash#slice</tt> to sanitize the hash of parameters before they are
 769       # passed to Active Record.
 770       #
 771       # For example, it could be the case that the list of protected attributes
 772       # for a given model depends on the role of the user:
 773       #
 774       #   # Assumes plan_id is not protected because it depends on the role.
 775       #   params[:account] = params[:account].except(:plan_id) unless admin?
 776       #   @account.update_attributes(params[:account])
 777       #
 778       # Note that +attr_protected+ is still applied to the received hash. Thus,
 779       # with this technique you can at most _extend_ the list of protected
 780       # attributes for a particular mass-assignment call.
 781       def attr_protected(*attributes)
 782         write_inheritable_attribute(:attr_protected, Set.new(attributes.map {|a| a.to_s}) + (protected_attributes || []))
 783       end
 784 
 785       # Returns an array of all the attributes that have been protected from mass-assignment.
 786       def protected_attributes # :nodoc:
 787         read_inheritable_attribute(:attr_protected)
 788       end
 789 
 790       # Specifies a white list of model attributes that can be set via
 791       # mass-assignment, such as <tt>new(attributes)</tt>,
 792       # <tt>update_attributes(attributes)</tt>, or
 793       # <tt>attributes=(attributes)</tt>
 794       #
 795       # This is the opposite of the +attr_protected+ macro: Mass-assignment
 796       # will only set attributes in this list, to assign to the rest of
 797       # attributes you can use direct writer methods. This is meant to protect
 798       # sensitive attributes from being overwritten by malicious users
 799       # tampering with URLs or forms. If you'd rather start from an all-open
 800       # default and restrict attributes as needed, have a look at
 801       # +attr_protected+.
 802       #
 803       #   class Customer < ActiveRecord::Base
 804       #     attr_accessible :name, :nickname
 805       #   end
 806       #
 807       #   customer = Customer.new(:name => "David", :nickname => "Dave", :credit_rating => "Excellent")
 808       #   customer.credit_rating # => nil
 809       #   customer.attributes = { :name => "Jolly fellow", :credit_rating => "Superb" }
 810       #   customer.credit_rating # => nil
 811       #
 812       #   customer.credit_rating = "Average"
 813       #   customer.credit_rating # => "Average"
 814       #
 815       # If the access logic of your application is richer you can use <tt>Hash#except</tt>
 816       # or <tt>Hash#slice</tt> to sanitize the hash of parameters before they are
 817       # passed to Active Record.
 818       #
 819       # For example, it could be the case that the list of accessible attributes
 820       # for a given model depends on the role of the user:
 821       #
 822       #   # Assumes plan_id is accessible because it depends on the role.
 823       #   params[:account] = params[:account].except(:plan_id) unless admin?
 824       #   @account.update_attributes(params[:account])
 825       #
 826       # Note that +attr_accessible+ is still applied to the received hash. Thus,
 827       # with this technique you can at most _narrow_ the list of accessible
 828       # attributes for a particular mass-assignment call.
 829       def attr_accessible(*attributes)
 830         write_inheritable_attribute(:attr_accessible, Set.new(attributes.map(&:to_s)) + (accessible_attributes || []))
 831       end
 832 
 833       # Returns an array of all the attributes that have been made accessible to mass-assignment.
 834       def accessible_attributes # :nodoc:
 835         read_inheritable_attribute(:attr_accessible)
 836       end
 837 
 838        # Attributes listed as readonly can be set for a new record, but will be ignored in database updates afterwards.
 839        def attr_readonly(*attributes)
 840          write_inheritable_attribute(:attr_readonly, Set.new(attributes.map(&:to_s)) + (readonly_attributes || []))
 841        end
 842 
 843        # Returns an array of all the attributes that have been specified as readonly.
 844        def readonly_attributes
 845          read_inheritable_attribute(:attr_readonly) || []
 846        end
 847 
 848       # If you have an attribute that needs to be saved to the database as an object, and retrieved as the same object,
 849       # then specify the name of that attribute using this method and it will be handled automatically.
 850       # The serialization is done through YAML. If +class_name+ is specified, the serialized object must be of that
 851       # class on retrieval or SerializationTypeMismatch will be raised.
 852       #
 853       # ==== Parameters
 854       #
 855       # * +attr_name+ - The field name that should be serialized.
 856       # * +class_name+ - Optional, class name that the object type should be equal to.
 857       #
 858       # ==== Example
 859       #   # Serialize a preferences attribute
 860       #   class User
 861       #     serialize :preferences
 862       #   end
 863       def serialize(attr_name, class_name = Object)
 864         serialized_attributes[attr_name.to_s] = class_name
 865       end
 866 
 867       # Returns a hash of all the attributes that have been specified for serialization as keys and their class restriction as values.
 868       def serialized_attributes
 869         read_inheritable_attribute(:attr_serialized) or write_inheritable_attribute(:attr_serialized, {})
 870       end
 871 
 872       # Guesses the table name (in forced lower-case) based on the name of the class in the inheritance hierarchy descending
 873       # directly from ActiveRecord::Base. So if the hierarchy looks like: Reply < Message < ActiveRecord::Base, then Message is used
 874       # to guess the table name even when called on Reply. The rules used to do the guess are handled by the Inflector class
 875       # in Active Support, which knows almost all common English inflections. You can add new inflections in config/initializers/inflections.rb.
 876       #
 877       # Nested classes are given table names prefixed by the singular form of
 878       # the parent's table name. Enclosing modules are not considered.
 879       #
 880       # ==== Examples
 881       #
 882       #   class Invoice < ActiveRecord::Base; end;
 883       #   file                  class               table_name
 884       #   invoice.rb            Invoice             invoices
 885       #
 886       #   class Invoice < ActiveRecord::Base; class Lineitem < ActiveRecord::Base; end; end;
 887       #   file                  class               table_name
 888       #   invoice.rb            Invoice::Lineitem   invoice_lineitems
 889       #
 890       #   module Invoice; class Lineitem < ActiveRecord::Base; end; end;
 891       #   file                  class               table_name
 892       #   invoice/lineitem.rb   Invoice::Lineitem   lineitems
 893       #
 894       # Additionally, the class-level +table_name_prefix+ is prepended and the
 895       # +table_name_suffix+ is appended.  So if you have "myapp_" as a prefix,
 896       # the table name guess for an Invoice class becomes "myapp_invoices".
 897       # Invoice::Lineitem becomes "myapp_invoice_lineitems".
 898       #
 899       # You can also overwrite this class method to allow for unguessable
 900       # links, such as a Mouse class with a link to a "mice" table. Example:
 901       #
 902       #   class Mouse < ActiveRecord::Base
 903       #     set_table_name "mice"
 904       #   end
 905       def table_name
 906         reset_table_name
 907       end
 908 
 909       def quoted_table_name
 910         @quoted_table_name ||= connection.quote_table_name(table_name)
 911       end
 912 
 913       def reset_table_name #:nodoc:
 914         base = base_class
 915 
 916         name =
 917           # STI subclasses always use their superclass' table.
 918           unless self == base
 919             base.table_name
 920           else
 921             # Nested classes are prefixed with singular parent table name.
 922             if parent < ActiveRecord::Base && !parent.abstract_class?
 923               contained = parent.table_name
 924               contained = contained.singularize if parent.pluralize_table_names
 925               contained << '_'
 926             end
 927             name = "#{table_name_prefix}#{contained}#{undecorated_table_name(base.name)}#{table_name_suffix}"
 928           end
 929 
 930         @quoted_table_name = nil
 931         set_table_name(name)
 932         name
 933       end
 934 
 935       # Defines the column name for use with single table inheritance
 936       # -- can be set in subclasses like so: self.inheritance_column = "type_id"
 937       def inheritance_column
 938         @inheritance_column ||= "type".freeze
 939       end
 940 
 941       # Lazy-set the sequence name to the connection's default.  This method
 942       # is only ever called once since set_sequence_name overrides it.
 943       def sequence_name #:nodoc:
 944         reset_sequence_name
 945       end
 946 
 947       def reset_sequence_name #:nodoc:
 948         default = connection.default_sequence_name(table_name, primary_key)
 949         set_sequence_name(default)
 950         default
 951       end
 952 
 953       # Sets the table name to use to the given value, or (if the value
 954       # is nil or false) to the value returned by the given block.
 955       #
 956       #   class Project < ActiveRecord::Base
 957       #     set_table_name "project"
 958       #   end
 959       def set_table_name(value = nil, &block)
 960         define_attr_method :table_name, value, &block
 961       end
 962       alias :table_name= :set_table_name
 963 
 964       # Sets the name of the inheritance column to use to the given value,
 965       # or (if the value # is nil or false) to the value returned by the
 966       # given block.
 967       #
 968       #   class Project < ActiveRecord::Base
 969       #     set_inheritance_column do
 970       #       original_inheritance_column + "_id"
 971       #     end
 972       #   end
 973       def set_inheritance_column(value = nil, &block)
 974         define_attr_method :inheritance_column, value, &block
 975       end
 976       alias :inheritance_column= :set_inheritance_column
 977 
 978       # Sets the name of the sequence to use when generating ids to the given
 979       # value, or (if the value is nil or false) to the value returned by the
 980       # given block. This is required for Oracle and is useful for any
 981       # database which relies on sequences for primary key generation.
 982       #
 983       # If a sequence name is not explicitly set when using Oracle or Firebird,
 984       # it will default to the commonly used pattern of: #{table_name}_seq
 985       #
 986       # If a sequence name is not explicitly set when using PostgreSQL, it
 987       # will discover the sequence corresponding to your primary key for you.
 988       #
 989       #   class Project < ActiveRecord::Base
 990       #     set_sequence_name "projectseq"   # default would have been "project_seq"
 991       #   end
 992       def set_sequence_name(value = nil, &block)
 993         define_attr_method :sequence_name, value, &block
 994       end
 995       alias :sequence_name= :set_sequence_name
 996 
 997       # Turns the +table_name+ back into a class name following the reverse rules of +table_name+.
 998       def class_name(table_name = table_name) # :nodoc:
 999         # remove any prefix and/or suffix from the table name
1000         class_name = table_name[table_name_prefix.length..-(table_name_suffix.length + 1)].camelize
1001         class_name = class_name.singularize if pluralize_table_names
1002         class_name
1003       end
1004 
1005       # Indicates whether the table associated with this class exists
1006       def table_exists?
1007         connection.table_exists?(table_name)
1008       end
1009 
1010       # Returns an array of column objects for the table associated with this class.
1011       def columns
1012         unless defined?(@columns) && @columns
1013           @columns = connection.columns(table_name, "#{name} Columns")
1014           @columns.each { |column| column.primary = column.name == primary_key }
1015         end
1016         @columns
1017       end
1018 
1019       # Returns a hash of column objects for the table associated with this class.
1020       def columns_hash
1021         @columns_hash ||= columns.inject({}) { |hash, column| hash[column.name] = column; hash }
1022       end
1023 
1024       # Returns an array of column names as strings.
1025       def column_names
1026         @column_names ||= columns.map { |column| column.name }
1027       end
1028 
1029       # Returns an array of column objects where the primary id, all columns ending in "_id" or "_count",
1030       # and columns used for single table inheritance have been removed.
1031       def content_columns
1032         @content_columns ||= columns.reject { |c| c.primary || c.name =~ /(_id|_count)$/ || c.name == inheritance_column }
1033       end
1034 
1035       # Returns a hash of all the methods added to query each of the columns in the table with the name of the method as the key
1036       # and true as the value. This makes it possible to do O(1) lookups in respond_to? to check if a given method for attribute
1037       # is available.
1038       def column_methods_hash #:nodoc:
1039         @dynamic_methods_hash ||= column_names.inject(Hash.new(false)) do |methods, attr|
1040           attr_name = attr.to_s
1041           methods[attr.to_sym]       = attr_name
1042           methods["#{attr}=".to_sym] = attr_name
1043           methods["#{attr}?".to_sym] = attr_name
1044           methods["#{attr}_before_type_cast".to_sym] = attr_name
1045           methods
1046         end
1047       end
1048 
1049       # Resets all the cached information about columns, which will cause them
1050       # to be reloaded on the next request.
1051       #
1052       # The most common usage pattern for this method is probably in a migration,
1053       # when just after creating a table you want to populate it with some default
1054       # values, eg:
1055       #
1056       #  class CreateJobLevels < ActiveRecord::Migration
1057       #    def self.up
1058       #      create_table :job_levels do |t|
1059       #        t.integer :id
1060       #        t.string :name
1061       #
1062       #        t.timestamps
1063       #      end
1064       #
1065       #      JobLevel.reset_column_information
1066       #      %w{assistant executive manager director}.each do |type|
1067       #        JobLevel.create(:name => type)
1068       #      end
1069       #    end
1070       #
1071       #    def self.down
1072       #      drop_table :job_levels
1073       #    end
1074       #  end
1075       def reset_column_information
1076         undefine_attribute_methods
1077         @column_names = @columns = @columns_hash = @content_columns = @dynamic_methods_hash = @inheritance_column = nil
1078         @arel_engine = @unscoped = @arel_table = nil
1079       end
1080 
1081       def reset_column_information_and_inheritable_attributes_for_all_subclasses#:nodoc:
1082         subclasses.each { |klass| klass.reset_inheritable_attributes; klass.reset_column_information }
1083       end
1084 
1085       # Set the lookup ancestors for ActiveModel.
1086       def lookup_ancestors #:nodoc:
1087         klass = self
1088         classes = [klass]
1089         while klass != klass.base_class
1090           classes << klass = klass.superclass
1091         end
1092         classes
1093       rescue
1094         # OPTIMIZE this rescue is to fix this test: ./test/cases/reflection_test.rb:56:in `test_human_name_for_column'
1095         # Apparently the method base_class causes some trouble.
1096         # It now works for sure.
1097         [self]
1098       end
1099 
1100       # Set the i18n scope to overwrite ActiveModel.
1101       def i18n_scope #:nodoc:
1102         :activerecord
1103       end
1104 
1105       # True if this isn't a concrete subclass needing a STI type condition.
1106       def descends_from_active_record?
1107         if superclass.abstract_class?
1108           superclass.descends_from_active_record?
1109         else
1110           superclass == Base || !columns_hash.include?(inheritance_column)
1111         end
1112       end
1113 
1114       def finder_needs_type_condition? #:nodoc:
1115         # This is like this because benchmarking justifies the strange :false stuff
1116         :true == (@finder_needs_type_condition ||= descends_from_active_record? ? :false : :true)
1117       end
1118 
1119       # Returns a string like 'Post id:integer, title:string, body:text'
1120       def inspect
1121         if self == Base
1122           super
1123         elsif abstract_class?
1124           "#{super}(abstract)"
1125         elsif table_exists?
1126           attr_list = columns.map { |c| "#{c.name}: #{c.type}" } * ', '
1127           "#{super}(#{attr_list})"
1128         else
1129           "#{super}(Table doesn't exist)"
1130         end
1131       end
1132 
1133       def quote_value(value, column = nil) #:nodoc:
1134         connection.quote(value,column)
1135       end
1136 
1137       # Used to sanitize objects before they're used in an SQL SELECT statement. Delegates to <tt>connection.quote</tt>.
1138       def sanitize(object) #:nodoc:
1139         connection.quote(object)
1140       end
1141 
1142       # Overwrite the default class equality method to provide support for association proxies.
1143       def ===(object)
1144         object.is_a?(self)
1145       end
1146 
1147       # Returns the base AR subclass that this class descends from. If A
1148       # extends AR::Base, A.base_class will return A. If B descends from A
1149       # through some arbitrarily deep hierarchy, B.base_class will return A.
1150       def base_class
1151         class_of_active_record_descendant(self)
1152       end
1153 
1154       # Set this to true if this is an abstract class (see <tt>abstract_class?</tt>).
1155       attr_accessor :abstract_class
1156 
1157       # Returns whether this class is a base AR class.  If A is a base class and
1158       # B descends from A, then B.base_class will return B.
1159       def abstract_class?
1160         defined?(@abstract_class) && @abstract_class == true
1161       end
1162 
1163       def respond_to?(method_id, include_private = false)
1164         if match = DynamicFinderMatch.match(method_id)
1165           return true if all_attributes_exists?(match.attribute_names)
1166         elsif match = DynamicScopeMatch.match(method_id)
1167           return true if all_attributes_exists?(match.attribute_names)
1168         end
1169 
1170         super
1171       end
1172 
1173       def sti_name
1174         store_full_sti_class ? name : name.demodulize
1175       end
1176 
1177       def unscoped
1178         @unscoped ||= Relation.new(self, arel_table)
1179         finder_needs_type_condition? ? @unscoped.where(type_condition) : @unscoped
1180       end
1181 
1182       def arel_table
1183         @arel_table ||= Arel::Table.new(table_name, :engine => arel_engine)
1184       end
1185 
1186       def arel_engine
1187         @arel_engine ||= begin
1188           if self == ActiveRecord::Base
1189             Arel::Table.engine
1190           else
1191             connection_handler.connection_pools[name] ? Arel::Sql::Engine.new(self) : superclass.arel_engine
1192           end
1193         end
1194       end
1195 
1196       private
1197         # Finder methods must instantiate through this method to work with the
1198         # single-table inheritance model that makes it possible to create
1199         # objects of different types from the same table.
1200         def instantiate(record)
1201           object = find_sti_class(record[inheritance_column]).allocate
1202 
1203           object.instance_variable_set(:'@attributes', record)
1204           object.instance_variable_set(:'@attributes_cache', {})
1205 
1206           object.send(:_run_find_callbacks)
1207           object.send(:_run_initialize_callbacks)
1208 
1209           object
1210         end
1211 
1212         def find_sti_class(type_name)
1213           if type_name.blank? || !columns_hash.include?(inheritance_column)
1214             self
1215           else
1216             begin
1217               compute_type(type_name)
1218             rescue NameError
1219               raise SubclassNotFound,
1220                 "The single-table inheritance mechanism failed to locate the subclass: '#{type_name}'. " +
1221                 "This error is raised because the column '#{inheritance_column}' is reserved for storing the class in case of inheritance. " +
1222                 "Please rename this column if you didn't intend it to be used for storing the inheritance class " +
1223                 "or overwrite #{name}.inheritance_column to use another column for that information."
1224             end
1225           end
1226         end
1227 
1228         # Nest the type name in the same module as this class.
1229         # Bar is "MyApp::Business::Bar" relative to MyApp::Business::Foo
1230         def type_name_with_module(type_name)
1231           if store_full_sti_class
1232             type_name
1233           else
1234             (/^::/ =~ type_name) ? type_name : "#{parent.name}::#{type_name}"
1235           end
1236         end
1237 
1238         def construct_finder_arel(options = {}, scope = nil)
1239           relation = options.is_a?(Hash) ? unscoped.apply_finder_options(options) : unscoped.merge(options)
1240           relation = scope.merge(relation) if scope
1241           relation
1242         end
1243 
1244         def type_condition
1245           sti_column = arel_table[inheritance_column]
1246           condition = sti_column.eq(sti_name)
1247           subclasses.each{|subclass| condition = condition.or(sti_column.eq(subclass.sti_name)) }
1248 
1249           condition
1250         end
1251 
1252         # Guesses the table name, but does not decorate it with prefix and suffix information.
1253         def undecorated_table_name(class_name = base_class.name)
1254           table_name = class_name.to_s.demodulize.underscore
1255           table_name = table_name.pluralize if pluralize_table_names
1256           table_name
1257         end
1258 
1259         # Enables dynamic finders like <tt>find_by_user_name(user_name)</tt> and <tt>find_by_user_name_and_password(user_name, password)</tt>
1260         # that are turned into <tt>where(:user_name => user_name).first</tt> and <tt>where(:user_name => user_name, :password => :password).first</tt>
1261         # respectively. Also works for <tt>all</tt> by using <tt>find_all_by_amount(50)</tt> that is turned into <tt>where(:amount => 50).all</tt>.
1262         #
1263         # It's even possible to use all the additional parameters to +find+. For example, the full interface for +find_all_by_amount+
1264         # is actually <tt>find_all_by_amount(amount, options)</tt>.
1265         #
1266         # Also enables dynamic scopes like scoped_by_user_name(user_name) and scoped_by_user_name_and_password(user_name, password) that
1267         # are turned into scoped(:conditions => ["user_name = ?", user_name]) and scoped(:conditions => ["user_name = ? AND password = ?", user_name, password])
1268         # respectively.
1269         #
1270         # Each dynamic finder, scope or initializer/creator is also defined in the class after it is first invoked, so that future
1271         # attempts to use it do not run through method_missing.
1272         def method_missing(method_id, *arguments, &block)
1273           if match = DynamicFinderMatch.match(method_id)
1274             attribute_names = match.attribute_names
1275             super unless all_attributes_exists?(attribute_names)
1276             if match.finder?
1277               options = arguments.extract_options!
1278               relation = options.any? ? construct_finder_arel(options, current_scoped_methods) : scoped
1279               relation.send :find_by_attributes, match, attribute_names, *arguments
1280             elsif match.instantiator?
1281               scoped.send :find_or_instantiator_by_attributes, match, attribute_names, *arguments, &block
1282             end
1283           elsif match = DynamicScopeMatch.match(method_id)
1284             attribute_names = match.attribute_names
1285             super unless all_attributes_exists?(attribute_names)
1286             if match.scope?
1287               self.class_eval %{
1288                 def self.#{method_id}(*args)                        # def self.scoped_by_user_name_and_password(*args)
1289                   options = args.extract_options!                   #   options = args.extract_options!
1290                   attributes = construct_attributes_from_arguments( #   attributes = construct_attributes_from_arguments(
1291                     [:#{attribute_names.join(',:')}], args          #     [:user_name, :password], args
1292                   )                                                 #   )
1293                                                                     #
1294                   scoped(:conditions => attributes)                 #   scoped(:conditions => attributes)
1295                 end                                                 # end
1296               }, __FILE__, __LINE__
1297               send(method_id, *arguments)
1298             end
1299           else
1300             super
1301           end
1302         end
1303 
1304         def construct_attributes_from_arguments(attribute_names, arguments)
1305           attributes = {}
1306           attribute_names.each_with_index { |name, idx| attributes[name] = arguments[idx] }
1307           attributes
1308         end
1309 
1310         # Similar in purpose to +expand_hash_conditions_for_aggregates+.
1311         def expand_attribute_names_for_aggregates(attribute_names)
1312           expanded_attribute_names = []
1313           attribute_names.each do |attribute_name|
1314             unless (aggregation = reflect_on_aggregation(attribute_name.to_sym)).nil?
1315               aggregate_mapping(aggregation).each do |field_attr, aggregate_attr|
1316                 expanded_attribute_names << field_attr
1317               end
1318             else
1319               expanded_attribute_names << attribute_name
1320             end
1321           end
1322           expanded_attribute_names
1323         end
1324 
1325         def all_attributes_exists?(attribute_names)
1326           attribute_names = expand_attribute_names_for_aggregates(attribute_names)
1327           attribute_names.all? { |name| column_methods_hash.include?(name.to_sym) }
1328         end
1329 
1330         def attribute_condition(quoted_column_name, argument)
1331           case argument
1332             when nil   then "#{quoted_column_name} IS ?"
1333             when Array, ActiveRecord::Associations::AssociationCollection, ActiveRecord::NamedScope::Scope then "#{quoted_column_name} IN (?)"
1334             when Range then if argument.exclude_end?
1335                               "#{quoted_column_name} >= ? AND #{quoted_column_name} < ?"
1336                             else
1337                               "#{quoted_column_name} BETWEEN ? AND ?"
1338                             end
1339             else            "#{quoted_column_name} = ?"
1340           end
1341         end
1342 
1343       protected
1344         # Scope parameters to method calls within the block.  Takes a hash of method_name => parameters hash.
1345         # method_name may be <tt>:find</tt> or <tt>:create</tt>. <tt>:find</tt> parameters may include the <tt>:conditions</tt>, <tt>:joins</tt>,
1346         # <tt>:include</tt>, <tt>:offset</tt>, <tt>:limit</tt>, and <tt>:readonly</tt> options. <tt>:create</tt> parameters are an attributes hash.
1347         #
1348         #   class Article < ActiveRecord::Base
1349         #     def self.create_with_scope
1350         #       with_scope(:find => { :conditions => "blog_id = 1" }, :create => { :blog_id => 1 }) do
1351         #         find(1) # => SELECT * from articles WHERE blog_id = 1 AND id = 1
1352         #         a = create(1)
1353         #         a.blog_id # => 1
1354         #       end
1355         #     end
1356         #   end
1357         #
1358         # In nested scopings, all previous parameters are overwritten by the innermost rule, with the exception of
1359         # <tt>:conditions</tt>, <tt>:include</tt>, and <tt>:joins</tt> options in <tt>:find</tt>, which are merged.
1360         #
1361         # <tt>:joins</tt> options are uniqued so multiple scopes can join in the same table without table aliasing
1362         # problems.  If you need to join multiple tables, but still want one of the tables to be uniqued, use the
1363         # array of strings format for your joins.
1364         #
1365         #   class Article < ActiveRecord::Base
1366         #     def self.find_with_scope
1367         #       with_scope(:find => { :conditions => "blog_id = 1", :limit => 1 }, :create => { :blog_id => 1 }) do
1368         #         with_scope(:find => { :limit => 10 }) do
1369         #           find(:all) # => SELECT * from articles WHERE blog_id = 1 LIMIT 10
1370         #         end
1371         #         with_scope(:find => { :conditions => "author_id = 3" }) do
1372         #           find(:all) # => SELECT * from articles WHERE blog_id = 1 AND author_id = 3 LIMIT 1
1373         #         end
1374         #       end
1375         #     end
1376         #   end
1377         #
1378         # You can ignore any previous scopings by using the <tt>with_exclusive_scope</tt> method.
1379         #
1380         #   class Article < ActiveRecord::Base
1381         #     def self.find_with_exclusive_scope
1382         #       with_scope(:find => { :conditions => "blog_id = 1", :limit => 1 }) do
1383         #         with_exclusive_scope(:find => { :limit => 10 })
1384         #           find(:all) # => SELECT * from articles LIMIT 10
1385         #         end
1386         #       end
1387         #     end
1388         #   end
1389         #
1390         # *Note*: the +:find+ scope also has effect on update and deletion methods,
1391         # like +update_all+ and +delete_all+.
1392         def with_scope(method_scoping = {}, action = :merge, &block)
1393           method_scoping = method_scoping.method_scoping if method_scoping.respond_to?(:method_scoping)
1394 
1395           if method_scoping.is_a?(Hash)
1396             # Dup first and second level of hash (method and params).
1397             method_scoping = method_scoping.inject({}) do |hash, (method, params)|
1398               hash[method] = (params == true) ? params : params.dup
1399               hash
1400             end
1401 
1402             method_scoping.assert_valid_keys([ :find, :create ])
1403             relation = construct_finder_arel(method_scoping[:find] || {})
1404 
1405             if current_scoped_methods && current_scoped_methods.create_with_value && method_scoping[:create]
1406               scope_for_create = if action == :merge
1407                 current_scoped_methods.create_with_value.merge(method_scoping[:create])
1408               else
1409                 method_scoping[:create]
1410               end
1411 
1412               relation = relation.create_with(scope_for_create)
1413             else
1414               scope_for_create = method_scoping[:create]
1415               scope_for_create ||= current_scoped_methods.create_with_value if current_scoped_methods
1416               relation = relation.create_with(scope_for_create) if scope_for_create
1417             end
1418 
1419             method_scoping = relation
1420           end
1421 
1422           method_scoping = current_scoped_methods.merge(method_scoping) if current_scoped_methods && action ==  :merge
1423 
1424           self.scoped_methods << method_scoping
1425           begin
1426             yield
1427           ensure
1428             self.scoped_methods.pop
1429           end
1430         end
1431 
1432         # Works like with_scope, but discards any nested properties.
1433         def with_exclusive_scope(method_scoping = {}, &block)
1434           with_scope(method_scoping, :overwrite, &block)
1435         end
1436 
1437         def subclasses #:nodoc:
1438           @@subclasses[self] ||= []
1439           @@subclasses[self] + extra = @@subclasses[self].inject([]) {|list, subclass| list + subclass.subclasses }
1440         end
1441 
1442         # Sets the default options for the model. The format of the
1443         # <tt>options</tt> argument is the same as in find.
1444         #
1445         #   class Person < ActiveRecord::Base
1446         #     default_scope :order => 'last_name, first_name'
1447         #   end
1448         def default_scope(options = {})
1449           self.default_scoping << construct_finder_arel(options)
1450         end
1451 
1452         def scoped_methods #:nodoc:
1453           key = :"#{self}_scoped_methods"
1454           Thread.current[key] = Thread.current[key].presence || self.default_scoping.dup
1455         end
1456 
1457         def current_scoped_methods #:nodoc:
1458           scoped_methods.last
1459         end
1460 
1461         # Returns the class type of the record using the current module as a prefix. So descendants of
1462         # MyApp::Business::Account would appear as MyApp::Business::AccountSubclass.
1463         def compute_type(type_name)
1464           modularized_name = type_name_with_module(type_name)
1465           silence_warnings do
1466             begin
1467               class_eval(modularized_name, __FILE__, __LINE__)
1468             rescue NameError
1469               class_eval(type_name, __FILE__, __LINE__)
1470             end
1471           end
1472         end
1473 
1474         # Returns the class descending directly from ActiveRecord::Base or an
1475         # abstract class, if any, in the inheritance hierarchy.
1476         def class_of_active_record_descendant(klass)
1477           if klass.superclass == Base || klass.superclass.abstract_class?
1478             klass
1479           elsif klass.superclass.nil?
1480             raise ActiveRecordError, "#{name} doesn't belong in a hierarchy descending from ActiveRecord"
1481           else
1482             class_of_active_record_descendant(klass.superclass)
1483           end
1484         end
1485 
1486         # Returns the name of the class descending directly from Active Record in the inheritance hierarchy.
1487         def class_name_of_active_record_descendant(klass) #:nodoc:
1488           klass.base_class.name
1489         end
1490 
1491         # Accepts an array, hash, or string of SQL conditions and sanitizes
1492         # them into a valid SQL fragment for a WHERE clause.
1493         #   ["name='%s' and group_id='%s'", "foo'bar", 4]  returns  "name='foo''bar' and group_id='4'"
1494         #   { :name => "foo'bar", :group_id => 4 }  returns "name='foo''bar' and group_id='4'"
1495         #   "name='foo''bar' and group_id='4'" returns "name='foo''bar' and group_id='4'"
1496         def sanitize_sql_for_conditions(condition, table_name = self.table_name)
1497           return nil if condition.blank?
1498 
1499           case condition
1500             when Array; sanitize_sql_array(condition)
1501             when Hash;  sanitize_sql_hash_for_conditions(condition, table_name)
1502             else        condition
1503           end
1504         end
1505         alias_method :sanitize_sql, :sanitize_sql_for_conditions
1506 
1507         # Accepts an array, hash, or string of SQL conditions and sanitizes
1508         # them into a valid SQL fragment for a SET clause.
1509         #   { :name => nil, :group_id => 4 }  returns "name = NULL , group_id='4'"
1510         def sanitize_sql_for_assignment(assignments)
1511           case assignments
1512             when Array; sanitize_sql_array(assignments)
1513             when Hash;  sanitize_sql_hash_for_assignment(assignments)
1514             else        assignments
1515           end
1516         end
1517 
1518         def aggregate_mapping(reflection)
1519           mapping = reflection.options[:mapping] || [reflection.name, reflection.name]
1520           mapping.first.is_a?(Array) ? mapping : [mapping]
1521         end
1522 
1523         # Accepts a hash of SQL conditions and replaces those attributes
1524         # that correspond to a +composed_of+ relationship with their expanded
1525         # aggregate attribute values.
1526         # Given:
1527         #     class Person < ActiveRecord::Base
1528         #       composed_of :address, :class_name => "Address",
1529         #         :mapping => [%w(address_street street), %w(address_city city)]
1530         #     end
1531         # Then:
1532         #     { :address => Address.new("813 abc st.", "chicago") }
1533         #       # => { :address_street => "813 abc st.", :address_city => "chicago" }
1534         def expand_hash_conditions_for_aggregates(attrs)
1535           expanded_attrs = {}
1536           attrs.each do |attr, value|
1537             unless (aggregation = reflect_on_aggregation(attr.to_sym)).nil?
1538               mapping = aggregate_mapping(aggregation)
1539               mapping.each do |field_attr, aggregate_attr|
1540                 if mapping.size == 1 && !value.respond_to?(aggregate_attr)
1541                   expanded_attrs[field_attr] = value
1542                 else
1543                   expanded_attrs[field_attr] = value.send(aggregate_attr)
1544                 end
1545               end
1546             else
1547               expanded_attrs[attr] = value
1548             end
1549           end
1550           expanded_attrs
1551         end
1552 
1553         # Sanitizes a hash of attribute/value pairs into SQL conditions for a WHERE clause.
1554         #   { :name => "foo'bar", :group_id => 4 }
1555         #     # => "name='foo''bar' and group_id= 4"
1556         #   { :status => nil, :group_id => [1,2,3] }
1557         #     # => "status IS NULL and group_id IN (1,2,3)"
1558         #   { :age => 13..18 }
1559         #     # => "age BETWEEN 13 AND 18"
1560         #   { 'other_records.id' => 7 }
1561         #     # => "`other_records`.`id` = 7"
1562         #   { :other_records => { :id => 7 } }
1563         #     # => "`other_records`.`id` = 7"
1564         # And for value objects on a composed_of relationship:
1565         #   { :address => Address.new("123 abc st.", "chicago") }
1566         #     # => "address_street='123 abc st.' and address_city='chicago'"
1567         def sanitize_sql_hash_for_conditions(attrs, default_table_name = self.table_name)
1568           attrs = expand_hash_conditions_for_aggregates(attrs)
1569 
1570           table = Arel::Table.new(self.table_name, :engine => arel_engine, :as => default_table_name)
1571           builder = PredicateBuilder.new(arel_engine)
1572           builder.build_from_hash(attrs, table).map(&:to_sql).join(' AND ')
1573         end
1574         alias_method :sanitize_sql_hash, :sanitize_sql_hash_for_conditions
1575 
1576         # Sanitizes a hash of attribute/value pairs into SQL conditions for a SET clause.
1577         #   { :status => nil, :group_id => 1 }
1578         #     # => "status = NULL , group_id = 1"
1579         def sanitize_sql_hash_for_assignment(attrs)
1580           attrs.map do |attr, value|
1581             "#{connection.quote_column_name(attr)} = #{quote_bound_value(value)}"
1582           end.join(', ')
1583         end
1584 
1585         # Accepts an array of conditions.  The array has each value
1586         # sanitized and interpolated into the SQL statement.
1587         #   ["name='%s' and group_id='%s'", "foo'bar", 4]  returns  "name='foo''bar' and group_id='4'"
1588         def sanitize_sql_array(ary)
1589           statement, *values = ary
1590           if values.first.is_a?(Hash) and statement =~ /:\w+/
1591             replace_named_bind_variables(statement, values.first)
1592           elsif statement.include?('?')
1593             replace_bind_variables(statement, values)
1594           else
1595             statement % values.collect { |value| connection.quote_string(value.to_s) }
1596           end
1597         end
1598 
1599         alias_method :sanitize_conditions, :sanitize_sql
1600 
1601         def replace_bind_variables(statement, values) #:nodoc:
1602           raise_if_bind_arity_mismatch(statement, statement.count('?'), values.size)
1603           bound = values.dup
1604           statement.gsub('?') { quote_bound_value(bound.shift) }
1605         end
1606 
1607         def replace_named_bind_variables(statement, bind_vars) #:nodoc:
1608           statement.gsub(/(:?):([a-zA-Z]\w*)/) do
1609             if $1 == ':' # skip postgresql casts
1610               $& # return the whole match
1611             elsif bind_vars.include?(match = $2.to_sym)
1612               quote_bound_value(bind_vars[match])
1613             else
1614               raise PreparedStatementInvalid, "missing value for :#{match} in #{statement}"
1615             end
1616           end
1617         end
1618 
1619         def expand_range_bind_variables(bind_vars) #:nodoc:
1620           expanded = []
1621 
1622           bind_vars.each do |var|
1623             next if var.is_a?(Hash)
1624 
1625             if var.is_a?(Range)
1626               expanded << var.first
1627               expanded << var.last
1628             else
1629               expanded << var
1630             end
1631           end
1632 
1633           expanded
1634         end
1635 
1636         def quote_bound_value(value) #:nodoc:
1637           if value.respond_to?(:map) && !value.acts_like?(:string)
1638             if value.respond_to?(:empty?) && value.empty?
1639               connection.quote(nil)
1640             else
1641               value.map { |v| connection.quote(v) }.join(',')
1642             end
1643           else
1644             connection.quote(value)
1645           end
1646         end
1647 
1648         def raise_if_bind_arity_mismatch(statement, expected, provided) #:nodoc:
1649           unless expected == provided
1650             raise PreparedStatementInvalid, "wrong number of bind variables (#{provided} for #{expected}) in: #{statement}"
1651           end
1652         end
1653 
1654         def encode_quoted_value(value) #:nodoc:
1655           quoted_value = connection.quote(value)
1656           quoted_value = "'#{quoted_value[1..-2].gsub(/\'/, "\\\\'")}'" if quoted_value.include?("\\\'") # (for ruby mode) "
1657           quoted_value
1658         end
1659     end
1660 
1661     public
1662       # New objects can be instantiated as either empty (pass no construction parameter) or pre-set with
1663       # attributes but not yet saved (pass a hash with key names matching the associated table column names).
1664       # In both instances, valid attribute keys are determined by the column names of the associated table --
1665       # hence you can't have attributes that aren't part of the table columns.
1666       def initialize(attributes = nil)
1667         @attributes = attributes_from_column_definition
1668         @attributes_cache = {}
1669         @new_record = true
1670         ensure_proper_type
1671         self.attributes = attributes unless attributes.nil?
1672 
1673         if scope = self.class.send(:current_scoped_methods)
1674           create_with = scope.scope_for_create
1675           create_with.each { |att,value| self.send("#{att}=", value) } if create_with
1676         end
1677 
1678         result = yield self if block_given?
1679         _run_initialize_callbacks
1680         result
1681       end
1682 
1683       # Cloned objects have no id assigned and are treated as new records. Note that this is a "shallow" clone
1684       # as it copies the object's attributes only, not its associations. The extent of a "deep" clone is
1685       # application specific and is therefore left to the application to implement according to its need.
1686       def initialize_copy(other)
1687         # Think the assertion which fails if the after_initialize callback goes at the end of the method is wrong. The
1688         # deleted clone method called new which therefore called the after_initialize callback. It then went on to copy
1689         # over the attributes. But if it's copying the attributes afterwards then it hasn't finished initializing right?
1690         # For example in the test suite the topic model's after_initialize method sets the author_email_address to
1691         # test@test.com. I would have thought this would mean that all cloned models would have an author email address
1692         # of test@test.com. However the test_clone test method seems to test that this is not the case. As a result the
1693         # after_initialize callback has to be run *before* the copying of the atrributes rather than afterwards in order
1694         # for all tests to pass. This makes no sense to me.
1695         callback(:after_initialize) if respond_to_without_attributes?(:after_initialize)
1696         cloned_attributes = other.clone_attributes(:read_attribute_before_type_cast)
1697         cloned_attributes.delete(self.class.primary_key)
1698         @attributes = cloned_attributes
1699         clear_aggregation_cache
1700         @attributes_cache = {}
1701         @new_record = true
1702         ensure_proper_type
1703 
1704         if scope = self.class.send(:current_scoped_methods)
1705           create_with = scope.scope_for_create
1706           create_with.each { |att,value| self.send("#{att}=", value) } if create_with
1707         end
1708       end
1709 
1710       # Returns a String, which Action Pack uses for constructing an URL to this
1711       # object. The default implementation returns this record's id as a String,
1712       # or nil if this record's unsaved.
1713       #
1714       # For example, suppose that you have a User model, and that you have a
1715       # <tt>map.resources :users</tt> route. Normally, +user_path+ will
1716       # construct a path with the user object's 'id' in it:
1717       #
1718       #   user = User.find_by_name('Phusion')
1719       #   user_path(user)  # => "/users/1"
1720       #
1721       # You can override +to_param+ in your model to make +user_path+ construct
1722       # a path using the user's name instead of the user's id:
1723       #
1724       #   class User < ActiveRecord::Base
1725       #     def to_param  # overridden
1726       #       name
1727       #     end
1728       #   end
1729       #
1730       #   user = User.find_by_name('Phusion')
1731       #   user_path(user)  # => "/users/Phusion"
1732       def to_param
1733         # We can't use alias_method here, because method 'id' optimizes itself on the fly.
1734         (id = self.id) ? id.to_s : nil # Be sure to stringify the id for routes
1735       end
1736 
1737       # Returns a cache key that can be used to identify this record.
1738       #
1739       # ==== Examples
1740       #
1741       #   Product.new.cache_key     # => "products/new"
1742       #   Product.find(5).cache_key # => "products/5" (updated_at not available)
1743       #   Person.find(5).cache_key  # => "people/5-20071224150000" (updated_at available)
1744       def cache_key
1745         case
1746         when new_record?
1747           "#{self.class.model_name.cache_key}/new"
1748         when timestamp = self[:updated_at]
1749           "#{self.class.model_name.cache_key}/#{id}-#{timestamp.to_s(:number)}"
1750         else
1751           "#{self.class.model_name.cache_key}/#{id}"
1752         end
1753       end
1754 
1755       def quoted_id #:nodoc:
1756         quote_value(id, column_for_attribute(self.class.primary_key))
1757       end
1758 
1759       # Returns true if this object hasn't been saved yet -- that is, a record for the object doesn't exist yet; otherwise, returns false.
1760       def new_record?
1761         @new_record || false
1762       end
1763 
1764       # Returns true if this object has been destroyed, otherwise returns false.
1765       def destroyed?
1766         @destroyed || false
1767       end
1768 
1769       # :call-seq:
1770       #   save(options)
1771       #
1772       # Saves the model.
1773       #
1774       # If the model is new a record gets created in the database, otherwise
1775       # the existing record gets updated.
1776       #
1777       # By default, save always run validations. If any of them fail the action
1778       # is cancelled and +save+ returns +false+. However, if you supply
1779       # :validate => false, validations are bypassed altogether. See
1780       # ActiveRecord::Validations for more information.
1781       #
1782       # There's a series of callbacks associated with +save+. If any of the
1783       # <tt>before_*</tt> callbacks return +false+ the action is cancelled and
1784       # +save+ returns +false+. See ActiveRecord::Callbacks for further
1785       # details.
1786       def save
1787         create_or_update
1788       end
1789 
1790       # Saves the model.
1791       #
1792       # If the model is new a record gets created in the database, otherwise
1793       # the existing record gets updated.
1794       #
1795       # With <tt>save!</tt> validations always run. If any of them fail
1796       # ActiveRecord::RecordInvalid gets raised. See ActiveRecord::Validations
1797       # for more information.
1798       #
1799       # There's a series of callbacks associated with <tt>save!</tt>. If any of
1800       # the <tt>before_*</tt> callbacks return +false+ the action is cancelled
1801       # and <tt>save!</tt> raises ActiveRecord::RecordNotSaved. See
1802       # ActiveRecord::Callbacks for further details.
1803       def save!
1804         create_or_update || raise(RecordNotSaved)
1805       end
1806 
1807       # Deletes the record in the database and freezes this instance to
1808       # reflect that no changes should be made (since they can't be
1809       # persisted). Returns the frozen instance.
1810       #
1811       # The row is simply removed with a SQL +DELETE+ statement on the
1812       # record's primary key, and no callbacks are executed.
1813       #
1814       # To enforce the object's +before_destroy+ and +after_destroy+
1815       # callbacks, Observer methods, or any <tt>:dependent</tt> association
1816       # options, use <tt>#destroy</tt>.
1817       def delete
1818         self.class.delete(id) unless new_record?
1819         @destroyed = true
1820         freeze
1821       end
1822 
1823       # Deletes the record in the database and freezes this instance to reflect that no changes should
1824       # be made (since they can't be persisted).
1825       def destroy
1826         unless new_record?
1827           self.class.unscoped.where(self.class.arel_table[self.class.primary_key].eq(id)).delete_all
1828         end
1829 
1830         @destroyed = true
1831         freeze
1832       end
1833 
1834       # Returns an instance of the specified +klass+ with the attributes of the current record. This is mostly useful in relation to
1835       # single-table inheritance structures where you want a subclass to appear as the superclass. This can be used along with record
1836       # identification in Action Pack to allow, say, <tt>Client < Company</tt> to do something like render <tt>:partial => @client.becomes(Company)</tt>
1837       # to render that instance using the companies/company partial instead of clients/client.
1838       #
1839       # Note: The new instance will share a link to the same attributes as the original class. So any change to the attributes in either
1840       # instance will affect the other.
1841       def becomes(klass)
1842         became = klass.new
1843         became.instance_variable_set("@attributes", @attributes)
1844         became.instance_variable_set("@attributes_cache", @attributes_cache)
1845         became.instance_variable_set("@new_record", new_record?)
1846         became
1847       end
1848 
1849       # Updates a single attribute and saves the record without going through the normal validation procedure.
1850       # This is especially useful for boolean flags on existing records. The regular +update_attribute+ method
1851       # in Base is replaced with this when the validations module is mixed in, which it is by default.
1852       def update_attribute(name, value)
1853         send(name.to_s + '=', value)
1854         save(:validate => false)
1855       end
1856 
1857       # Updates all the attributes from the passed-in Hash and saves the record. If the object is invalid, the saving will
1858       # fail and false will be returned.
1859       def update_attributes(attributes)
1860         self.attributes = attributes
1861         save
1862       end
1863 
1864       # Updates an object just like Base.update_attributes but calls save! instead of save so an exception is raised if the record is invalid.
1865       def update_attributes!(attributes)
1866         self.attributes = attributes
1867         save!
1868       end
1869 
1870       # Initializes +attribute+ to zero if +nil+ and adds the value passed as +by+ (default is 1).
1871       # The increment is performed directly on the underlying attribute, no setter is invoked.
1872       # Only makes sense for number-based attributes. Returns +self+.
1873       def increment(attribute, by = 1)
1874         self[attribute] ||= 0
1875         self[attribute] += by
1876         self
1877       end
1878 
1879       # Wrapper around +increment+ that saves the record. This method differs from
1880       # its non-bang version in that it passes through the attribute setter.
1881       # Saving is not subjected to validation checks. Returns +true+ if the
1882       # record could be saved.
1883       def increment!(attribute, by = 1)
1884         increment(attribute, by).update_attribute(attribute, self[attribute])
1885       end
1886 
1887       # Initializes +attribute+ to zero if +nil+ and subtracts the value passed as +by+ (default is 1).
1888       # The decrement is performed directly on the underlying attribute, no setter is invoked.
1889       # Only makes sense for number-based attributes. Returns +self+.
1890       def decrement(attribute, by = 1)
1891         self[attribute] ||= 0
1892         self[attribute] -= by
1893         self
1894       end
1895 
1896       # Wrapper around +decrement+ that saves the record. This method differs from
1897       # its non-bang version in that it passes through the attribute setter.
1898       # Saving is not subjected to validation checks. Returns +true+ if the
1899       # record could be saved.
1900       def decrement!(attribute, by = 1)
1901         decrement(attribute, by).update_attribute(attribute, self[attribute])
1902       end
1903 
1904       # Assigns to +attribute+ the boolean opposite of <tt>attribute?</tt>. So
1905       # if the predicate returns +true+ the attribute will become +false+. This
1906       # method toggles directly the underlying value without calling any setter.
1907       # Returns +self+.
1908       def toggle(attribute)
1909         self[attribute] = !send("#{attribute}?")
1910         self
1911       end
1912 
1913       # Wrapper around +toggle+ that saves the record. This method differs from
1914       # its non-bang version in that it passes through the attribute setter.
1915       # Saving is not subjected to validation checks. Returns +true+ if the
1916       # record could be saved.
1917       def toggle!(attribute)
1918         toggle(attribute).update_attribute(attribute, self[attribute])
1919       end
1920 
1921       # Reloads the attributes of this object from the database.
1922       # The optional options argument is passed to find when reloading so you
1923       # may do e.g. record.reload(:lock => true) to reload the same record with
1924       # an exclusive row lock.
1925       def reload(options = nil)
1926         clear_aggregation_cache
1927         clear_association_cache
1928         @attributes.update(self.class.find(self.id, options).instance_variable_get('@attributes'))
1929         @attributes_cache = {}
1930         self
1931       end
1932 
1933       # Returns true if the given attribute is in the attributes hash
1934       def has_attribute?(attr_name)
1935         @attributes.has_key?(attr_name.to_s)
1936       end
1937 
1938       # Returns an array of names for the attributes available on this object sorted alphabetically.
1939       def attribute_names
1940         @attributes.keys.sort
1941       end
1942 
1943       # Returns the value of the attribute identified by <tt>attr_name</tt> after it has been typecast (for example,
1944       # "2004-12-12" in a data column is cast to a date object, like Date.new(2004, 12, 12)).
1945       # (Alias for the protected read_attribute method).
1946       def [](attr_name)
1947         read_attribute(attr_name)
1948       end
1949 
1950       # Updates the attribute identified by <tt>attr_name</tt> with the specified +value+.
1951       # (Alias for the protected write_attribute method).
1952       def []=(attr_name, value)
1953         write_attribute(attr_name, value)
1954       end
1955 
1956       # Allows you to set all the attributes at once by passing in a hash with keys
1957       # matching the attribute names (which again matches the column names).
1958       #
1959       # If +guard_protected_attributes+ is true (the default), then sensitive
1960       # attributes can be protected from this form of mass-assignment by using
1961       # the +attr_protected+ macro. Or you can alternatively specify which
1962       # attributes *can* be accessed with the +attr_accessible+ macro. Then all the
1963       # attributes not included in that won't be allowed to be mass-assigned.
1964       #
1965       #   class User < ActiveRecord::Base
1966       #     attr_protected :is_admin
1967       #   end
1968       #
1969       #   user = User.new
1970       #   user.attributes = { :username => 'Phusion', :is_admin => true }
1971       #   user.username   # => "Phusion"
1972       #   user.is_admin?  # => false
1973       #
1974       #   user.send(:attributes=, { :username => 'Phusion', :is_admin => true }, false)
1975       #   user.is_admin?  # => true
1976       def attributes=(new_attributes, guard_protected_attributes = true)
1977         return if new_attributes.nil?
1978         attributes = new_attributes.dup
1979         attributes.stringify_keys!
1980 
1981         multi_parameter_attributes = []
1982         attributes = remove_attributes_protected_from_mass_assignment(attributes) if guard_protected_attributes
1983 
1984         attributes.each do |k, v|
1985           if k.include?("(")
1986             multi_parameter_attributes << [ k, v ]
1987           else
1988             respond_to?(:"#{k}=") ? send(:"#{k}=", v) : raise(UnknownAttributeError, "unknown attribute: #{k}")
1989           end
1990         end
1991 
1992         assign_multiparameter_attributes(multi_parameter_attributes)
1993       end
1994 
1995       # Returns a hash of all the attributes with their names as keys and the values of the attributes as values.
1996       def attributes
1997         self.attribute_names.inject({}) do |attrs, name|
1998           attrs[name] = read_attribute(name)
1999           attrs
2000         end
2001       end
2002 
2003       # Returns an <tt>#inspect</tt>-like string for the value of the
2004       # attribute +attr_name+. String attributes are elided after 50
2005       # characters, and Date and Time attributes are returned in the
2006       # <tt>:db</tt> format. Other attributes return the value of
2007       # <tt>#inspect</tt> without modification.
2008       #
2009       #   person = Person.create!(:name => "David Heinemeier Hansson " * 3)
2010       #
2011       #   person.attribute_for_inspect(:name)
2012       #   # => '"David Heinemeier Hansson David Heinemeier Hansson D..."'
2013       #
2014       #   person.attribute_for_inspect(:created_at)
2015       #   # => '"2009-01-12 04:48:57"'
2016       def attribute_for_inspect(attr_name)
2017         value = read_attribute(attr_name)
2018 
2019         if value.is_a?(String) && value.length > 50
2020           "#{value[0..50]}...".inspect
2021         elsif value.is_a?(Date) || value.is_a?(Time)
2022           %("#{value.to_s(:db)}")
2023         else
2024           value.inspect
2025         end
2026       end
2027 
2028       # Returns true if the specified +attribute+ has been set by the user or by a database load and is neither
2029       # nil nor empty? (the latter only applies to objects that respond to empty?, most notably Strings).
2030       def attribute_present?(attribute)
2031         value = read_attribute(attribute)
2032         !value.blank?
2033       end
2034 
2035       # Returns the column object for the named attribute.
2036       def column_for_attribute(name)
2037         self.class.columns_hash[name.to_s]
2038       end
2039 
2040       # Returns true if the +comparison_object+ is the same object, or is of the same type and has the same id.
2041       def ==(comparison_object)
2042         comparison_object.equal?(self) ||
2043           (comparison_object.instance_of?(self.class) &&
2044             comparison_object.id == id &&
2045             !comparison_object.new_record?)
2046       end
2047 
2048       # Delegates to ==
2049       def eql?(comparison_object)
2050         self == (comparison_object)
2051       end
2052 
2053       # Delegates to id in order to allow two records of the same type and id to work with something like:
2054       #   [ Person.find(1), Person.find(2), Person.find(3) ] & [ Person.find(1), Person.find(4) ] # => [ Person.find(1) ]
2055       def hash
2056         id.hash
2057       end
2058 
2059       # Freeze the attributes hash such that associations are still accessible, even on destroyed records.
2060       def freeze
2061         @attributes.freeze; self
2062       end
2063 
2064       # Returns +true+ if the attributes hash has been frozen.
2065       def frozen?
2066         @attributes.frozen?
2067       end
2068 
2069       # Returns duplicated record with unfreezed attributes.
2070       def dup
2071         obj = super
2072         obj.instance_variable_set('@attributes', instance_variable_get('@attributes').dup)
2073         obj
2074       end
2075 
2076       # Returns +true+ if the record is read only. Records loaded through joins with piggy-back
2077       # attributes will be marked as read only since they cannot be saved.
2078       def readonly?
2079         defined?(@readonly) && @readonly == true
2080       end
2081 
2082       # Marks this record as read only.
2083       def readonly!
2084         @readonly = true
2085       end
2086 
2087       # Returns the contents of the record as a nicely formatted string.
2088       def inspect
2089         attributes_as_nice_string = self.class.column_names.collect { |name|
2090           if has_attribute?(name) || new_record?
2091             "#{name}: #{attribute_for_inspect(name)}"
2092           end
2093         }.compact.join(", ")
2094         "#<#{self.class} #{attributes_as_nice_string}>"
2095       end
2096 
2097     protected
2098       def clone_attributes(reader_method = :read_attribute, attributes = {})
2099         self.attribute_names.inject(attributes) do |attrs, name|
2100           attrs[name] = clone_attribute_value(reader_method, name)
2101           attrs
2102         end
2103       end
2104 
2105       def clone_attribute_value(reader_method, attribute_name)
2106         value = send(reader_method, attribute_name)
2107         value.duplicable? ? value.clone : value
2108       rescue TypeError, NoMethodError
2109         value
2110       end
2111 
2112     private
2113       def create_or_update
2114         raise ReadOnlyRecord if readonly?
2115         result = new_record? ? create : update
2116         result != false
2117       end
2118 
2119       # Updates the associated record with values matching those of the instance attributes.
2120       # Returns the number of affected rows.
2121       def update(attribute_names = @attributes.keys)
2122         attributes_with_values = arel_attributes_values(false, false, attribute_names)
2123         return 0 if attributes_with_values.empty?
2124         self.class.unscoped.where(self.class.arel_table[self.class.primary_key].eq(id)).arel.update(attributes_with_values)
2125       end
2126 
2127       # Creates a record with values matching those of the instance attributes
2128       # and returns its id.
2129       def create
2130         if self.id.nil? && connection.prefetch_primary_key?(self.class.table_name)
2131           self.id = connection.next_sequence_value(self.class.sequence_name)
2132         end
2133 
2134         attributes_values = arel_attributes_values
2135 
2136         new_id = if attributes_values.empty?
2137           self.class.unscoped.insert connection.empty_insert_statement_value
2138         else
2139           self.class.unscoped.insert attributes_values
2140         end
2141 
2142         self.id ||= new_id
2143 
2144         @new_record = false
2145         id
2146       end
2147 
2148       # Sets the attribute used for single table inheritance to this class name if this is not the ActiveRecord::Base descendant.
2149       # Considering the hierarchy Reply < Message < ActiveRecord::Base, this makes it possible to do Reply.new without having to
2150       # set <tt>Reply[Reply.inheritance_column] = "Reply"</tt> yourself. No such attribute would be set for objects of the
2151       # Message class in that example.
2152       def ensure_proper_type
2153         unless self.class.descends_from_active_record?
2154           write_attribute(self.class.inheritance_column, self.class.sti_name)
2155         end
2156       end
2157 
2158       def remove_attributes_protected_from_mass_assignment(attributes)
2159         safe_attributes =
2160           if self.class.accessible_attributes.nil? && self.class.protected_attributes.nil?
2161             attributes.reject { |key, value| attributes_protected_by_default.include?(key.gsub(/\(.+/, "")) }
2162           elsif self.class.protected_attributes.nil?
2163             attributes.reject { |key, value| !self.class.accessible_attributes.include?(key.gsub(/\(.+/, "")) || attributes_protected_by_default.include?(key.gsub(/\(.+/, "")) }
2164           elsif self.class.accessible_attributes.nil?
2165             attributes.reject { |key, value| self.class.protected_attributes.include?(key.gsub(/\(.+/,"")) || attributes_protected_by_default.include?(key.gsub(/\(.+/, "")) }
2166           else
2167             raise "Declare either attr_protected or attr_accessible for #{self.class}, but not both."
2168           end
2169 
2170         removed_attributes = attributes.keys - safe_attributes.keys
2171 
2172         if removed_attributes.any?
2173           log_protected_attribute_removal(removed_attributes)
2174         end
2175 
2176         safe_attributes
2177       end
2178 
2179       # Removes attributes which have been marked as readonly.
2180       def remove_readonly_attributes(attributes)
2181         unless self.class.readonly_attributes.nil?
2182           attributes.delete_if { |key, value| self.class.readonly_attributes.include?(key.gsub(/\(.+/,"")) }
2183         else
2184           attributes
2185         end
2186       end
2187 
2188       def log_protected_attribute_removal(*attributes)
2189         if logger
2190           logger.debug "WARNING: Can't mass-assign these protected attributes: #{attributes.join(', ')}"
2191         end
2192       end
2193 
2194       # The primary key and inheritance column can never be set by mass-assignment for security reasons.
2195       def attributes_protected_by_default
2196         default = [ self.class.primary_key, self.class.inheritance_column ]
2197         default << 'id' unless self.class.primary_key.eql? 'id'
2198         default
2199       end
2200 
2201       # Returns a copy of the attributes hash where all the values have been safely quoted for use in
2202       # an SQL statement.
2203       def attributes_with_quotes(include_primary_key = true, include_readonly_attributes = true, attribute_names = @attributes.keys)
2204         quoted = {}
2205         connection = self.class.connection
2206         attribute_names.each do |name|
2207           if (column = column_for_attribute(name)) && (include_primary_key || !column.primary)
2208             value = read_attribute(name)
2209 
2210             # We need explicit to_yaml because quote() does not properly convert Time/Date fields to YAML.
2211             if value && self.class.serialized_attributes.has_key?(name) && (value.acts_like?(:date) || value.acts_like?(:time))
2212               value = value.to_yaml
2213             end
2214 
2215             quoted[name] = connection.quote(value, column)
2216           end
2217         end
2218         include_readonly_attributes ? quoted : remove_readonly_attributes(quoted)
2219       end
2220 
2221       # Returns a copy of the attributes hash where all the values have been safely quoted for use in
2222       # an Arel insert/update method.
2223       def arel_attributes_values(include_primary_key = true, include_readonly_attributes = true, attribute_names = @attributes.keys)
2224         attrs = {}
2225         attribute_names.each do |name|
2226           if (column = column_for_attribute(name)) && (include_primary_key || !column.primary)
2227 
2228             if include_readonly_attributes || (!include_readonly_attributes && !self.class.readonly_attributes.include?(name))
2229               value = read_attribute(name)
2230 
2231               if value && ((self.class.serialized_attributes.has_key?(name) && (value.acts_like?(:date) || value.acts_like?(:time))) || value.is_a?(Hash) || value.is_a?(Array))
2232                 value = value.to_yaml
2233               end
2234               attrs[self.class.arel_table[name]] = value
2235             end
2236           end
2237         end
2238         attrs
2239       end
2240 
2241       # Quote strings appropriately for SQL statements.
2242       def quote_value(value, column = nil)
2243         self.class.connection.quote(value, column)
2244       end
2245 
2246       # Interpolate custom SQL string in instance context.
2247       # Optional record argument is meant for custom insert_sql.
2248       def interpolate_sql(sql, record = nil)
2249         instance_eval("%@#{sql.gsub('@', '\@')}@")
2250       end
2251 
2252       # Initializes the attributes array with keys matching the columns from the linked table and
2253       # the values matching the corresponding default value of that column, so
2254       # that a new instance, or one populated from a passed-in Hash, still has all the attributes
2255       # that instances loaded from the database would.
2256       def attributes_from_column_definition
2257         self.class.columns.inject({}) do |attributes, column|
2258           attributes[column.name] = column.default unless column.name == self.class.primary_key
2259           attributes
2260         end
2261       end
2262 
2263       # Instantiates objects for all attribute classes that needs more than one constructor parameter. This is done
2264       # by calling new on the column type or aggregation type (through composed_of) object with these parameters.
2265       # So having the pairs written_on(1) = "2004", written_on(2) = "6", written_on(3) = "24", will instantiate
2266       # written_on (a date type) with Date.new("2004", "6", "24"). You can also specify a typecast character in the
2267       # parentheses to have the parameters typecasted before they're used in the constructor. Use i for Fixnum, f for Float,
2268       # s for String, and a for Array. If all the values for a given attribute are empty, the attribute will be set to nil.
2269       def assign_multiparameter_attributes(pairs)
2270         execute_callstack_for_multiparameter_attributes(
2271           extract_callstack_for_multiparameter_attributes(pairs)
2272         )
2273       end
2274 
2275       def instantiate_time_object(name, values)
2276         if self.class.send(:create_time_zone_conversion_attribute?, name, column_for_attribute(name))
2277           Time.zone.local(*values)
2278         else
2279           Time.time_with_datetime_fallback(@@default_timezone, *values)
2280         end
2281       end
2282 
2283       def execute_callstack_for_multiparameter_attributes(callstack)
2284         errors = []
2285         callstack.each do |name, values_with_empty_parameters|
2286           begin
2287             klass = (self.class.reflect_on_aggregation(name.to_sym) || column_for_attribute(name)).klass
2288             # in order to allow a date to be set without a year, we must keep the empty values.
2289             # Otherwise, we wouldn't be able to distinguish it from a date with an empty day.
2290             values = values_with_empty_parameters.reject(&:nil?)
2291 
2292             if values.empty?
2293               send(name + "=", nil)
2294             else
2295 
2296               value = if Time == klass
2297                 instantiate_time_object(name, values)
2298               elsif Date == klass
2299                 begin
2300                   values = values_with_empty_parameters.collect do |v| v.nil? ? 1 : v end
2301                   Date.new(*values)
2302                 rescue ArgumentError => ex # if Date.new raises an exception on an invalid date
2303                   instantiate_time_object(name, values).to_date # we instantiate Time object and convert it back to a date thus using Time's logic in handling invalid dates
2304                 end
2305               else
2306                 klass.new(*values)
2307               end
2308 
2309               send(name + "=", value)
2310             end
2311           rescue => ex
2312             errors << AttributeAssignmentError.new("error on assignment #{values.inspect} to #{name}", ex, name)
2313           end
2314         end
2315         unless errors.empty?
2316           raise MultiparameterAssignmentErrors.new(errors), "#{errors.size} error(s) on assignment of multiparameter attributes"
2317         end
2318       end
2319 
2320       def extract_callstack_for_multiparameter_attributes(pairs)
2321         attributes = { }
2322 
2323         for pair in pairs
2324           multiparameter_name, value = pair
2325           attribute_name = multiparameter_name.split("(").first
2326           attributes[attribute_name] = [] unless attributes.include?(attribute_name)
2327 
2328           parameter_value = value.empty? ? nil : type_cast_attribute_value(multiparameter_name, value)
2329           attributes[attribute_name] << [ find_parameter_position(multiparameter_name), parameter_value ]
2330         end
2331 
2332         attributes.each { |name, values| attributes[name] = values.sort_by{ |v| v.first }.collect { |v| v.last } }
2333       end
2334 
2335       def type_cast_attribute_value(multiparameter_name, value)
2336         multiparameter_name =~ /\([0-9]*([if])\)/ ? value.send("to_" + $1) : value
2337       end
2338 
2339       def find_parameter_position(multiparameter_name)
2340         multiparameter_name.scan(/\(([0-9]*).*\)/).first.first
2341       end
2342 
2343       # Returns a comma-separated pair list, like "key1 = val1, key2 = val2".
2344       def comma_pair_list(hash)
2345         hash.inject([]) { |list, pair| list << "#{pair.first} = #{pair.last}" }.join(", ")
2346       end
2347 
2348       def quote_columns(quoter, hash)
2349         hash.inject({}) do |quoted, (name, value)|
2350           quoted[quoter.quote_column_name(name)] = value
2351           quoted
2352         end
2353       end
2354 
2355       def quoted_comma_pair_list(quoter, hash)
2356         comma_pair_list(quote_columns(quoter, hash))
2357       end
2358 
2359       def convert_number_column_value(value)
2360         if value == false
2361           0
2362         elsif value == true
2363           1
2364         elsif value.is_a?(String) && value.blank?
2365           nil
2366         else
2367           value
2368         end
2369       end
2370 
2371       def object_from_yaml(string)
2372         return string unless string.is_a?(String) && string =~ /^---/
2373         YAML::load(string) rescue string
2374       end
2375   end
2376 
2377   Base.class_eval do
2378     extend ActiveModel::Naming
2379     extend QueryCache::ClassMethods
2380     extend ActiveSupport::Benchmarkable
2381 
2382     include Validations
2383     include Locking::Optimistic, Locking::Pessimistic
2384     include AttributeMethods
2385     include AttributeMethods::Read, AttributeMethods::Write, AttributeMethods::BeforeTypeCast, AttributeMethods::Query
2386     include AttributeMethods::PrimaryKey
2387     include AttributeMethods::TimeZoneConversion
2388     include AttributeMethods::Dirty
2389     include Callbacks, ActiveModel::Observing, Timestamp
2390     include Associations, AssociationPreload, NamedScope
2391     include ActiveModel::Conversion
2392 
2393     # AutosaveAssociation needs to be included before Transactions, because we want
2394     # #save_with_autosave_associations to be wrapped inside a transaction.
2395     include AutosaveAssociation, NestedAttributes
2396 
2397     include Aggregations, Transactions, Reflection, Batches, Serialization
2398 
2399   end
2400 end
2401 
2402 # TODO: Remove this and make it work with LAZY flag
2403 require 'active_record/connection_adapters/abstract_adapter'