273 lines
8.5 KiB
Ruby
273 lines
8.5 KiB
Ruby
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require "active_support/hash_with_indifferent_access"
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require "active_support/core_ext/object/duplicable"
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module ActiveModel
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# == Active \Model \Dirty
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#
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# Provides a way to track changes in your object in the same way as
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# Active Record does.
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#
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# The requirements for implementing ActiveModel::Dirty are:
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#
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# * <tt>include ActiveModel::Dirty</tt> in your object.
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# * Call <tt>define_attribute_methods</tt> passing each method you want to
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# track.
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# * Call <tt>[attr_name]_will_change!</tt> before each change to the tracked
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# attribute.
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# * Call <tt>changes_applied</tt> after the changes are persisted.
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# * Call <tt>clear_changes_information</tt> when you want to reset the changes
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# information.
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# * Call <tt>restore_attributes</tt> when you want to restore previous data.
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#
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# A minimal implementation could be:
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#
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# class Person
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# include ActiveModel::Dirty
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#
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# define_attribute_methods :name
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#
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# def initialize
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# @name = nil
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# end
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#
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# def name
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# @name
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# end
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#
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# def name=(val)
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# name_will_change! unless val == @name
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# @name = val
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# end
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#
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# def save
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# # do persistence work
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#
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# changes_applied
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# end
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#
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# def reload!
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# # get the values from the persistence layer
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#
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# clear_changes_information
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# end
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#
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# def rollback!
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# restore_attributes
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# end
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# end
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#
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# A newly instantiated +Person+ object is unchanged:
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#
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# person = Person.new
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# person.changed? # => false
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#
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# Change the name:
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#
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# person.name = 'Bob'
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# person.changed? # => true
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# person.name_changed? # => true
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# person.name_changed?(from: nil, to: "Bob") # => true
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# person.name_was # => nil
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# person.name_change # => [nil, "Bob"]
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# person.name = 'Bill'
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# person.name_change # => [nil, "Bill"]
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#
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# Save the changes:
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#
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# person.save
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# person.changed? # => false
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# person.name_changed? # => false
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#
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# Reset the changes:
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#
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# person.previous_changes # => {"name" => [nil, "Bill"]}
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# person.name_previously_changed? # => true
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# person.name_previous_change # => [nil, "Bill"]
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# person.reload!
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# person.previous_changes # => {}
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#
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# Rollback the changes:
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#
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# person.name = "Uncle Bob"
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# person.rollback!
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# person.name # => "Bill"
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# person.name_changed? # => false
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#
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# Assigning the same value leaves the attribute unchanged:
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#
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# person.name = 'Bill'
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# person.name_changed? # => false
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# person.name_change # => nil
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#
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# Which attributes have changed?
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#
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# person.name = 'Bob'
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# person.changed # => ["name"]
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# person.changes # => {"name" => ["Bill", "Bob"]}
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#
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# If an attribute is modified in-place then make use of
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# <tt>[attribute_name]_will_change!</tt> to mark that the attribute is changing.
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# Otherwise \Active \Model can't track changes to in-place attributes. Note
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# that Active Record can detect in-place modifications automatically. You do
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# not need to call <tt>[attribute_name]_will_change!</tt> on Active Record models.
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#
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# person.name_will_change!
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# person.name_change # => ["Bill", "Bill"]
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# person.name << 'y'
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# person.name_change # => ["Bill", "Billy"]
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module Dirty
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extend ActiveSupport::Concern
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include ActiveModel::AttributeMethods
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OPTION_NOT_GIVEN = Object.new # :nodoc:
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private_constant :OPTION_NOT_GIVEN
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included do
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attribute_method_suffix "_changed?", "_change", "_will_change!", "_was"
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attribute_method_suffix "_previously_changed?", "_previous_change"
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attribute_method_affix prefix: "restore_", suffix: "!"
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end
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# Returns +true+ if any of the attributes have unsaved changes, +false+ otherwise.
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#
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# person.changed? # => false
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# person.name = 'bob'
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# person.changed? # => true
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def changed?
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changed_attributes.present?
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end
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# Returns an array with the name of the attributes with unsaved changes.
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#
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# person.changed # => []
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# person.name = 'bob'
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# person.changed # => ["name"]
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def changed
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changed_attributes.keys
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end
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# Returns a hash of changed attributes indicating their original
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# and new values like <tt>attr => [original value, new value]</tt>.
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#
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# person.changes # => {}
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# person.name = 'bob'
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# person.changes # => { "name" => ["bill", "bob"] }
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def changes
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ActiveSupport::HashWithIndifferentAccess[changed.map { |attr| [attr, attribute_change(attr)] }]
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end
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# Returns a hash of attributes that were changed before the model was saved.
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#
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# person.name # => "bob"
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# person.name = 'robert'
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# person.save
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# person.previous_changes # => {"name" => ["bob", "robert"]}
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def previous_changes
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@previously_changed ||= ActiveSupport::HashWithIndifferentAccess.new
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end
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# Returns a hash of the attributes with unsaved changes indicating their original
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# values like <tt>attr => original value</tt>.
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#
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# person.name # => "bob"
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# person.name = 'robert'
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# person.changed_attributes # => {"name" => "bob"}
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def changed_attributes
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@changed_attributes ||= ActiveSupport::HashWithIndifferentAccess.new
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end
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# Handles <tt>*_changed?</tt> for +method_missing+.
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def attribute_changed?(attr, from: OPTION_NOT_GIVEN, to: OPTION_NOT_GIVEN) # :nodoc:
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!!changes_include?(attr) &&
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(to == OPTION_NOT_GIVEN || to == __send__(attr)) &&
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(from == OPTION_NOT_GIVEN || from == changed_attributes[attr])
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end
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# Handles <tt>*_was</tt> for +method_missing+.
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def attribute_was(attr) # :nodoc:
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attribute_changed?(attr) ? changed_attributes[attr] : __send__(attr)
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end
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# Handles <tt>*_previously_changed?</tt> for +method_missing+.
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def attribute_previously_changed?(attr) #:nodoc:
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previous_changes_include?(attr)
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end
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# Restore all previous data of the provided attributes.
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def restore_attributes(attributes = changed)
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attributes.each { |attr| restore_attribute! attr }
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end
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private
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# Returns +true+ if attr_name is changed, +false+ otherwise.
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def changes_include?(attr_name)
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attributes_changed_by_setter.include?(attr_name)
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end
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alias attribute_changed_by_setter? changes_include?
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# Returns +true+ if attr_name were changed before the model was saved,
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# +false+ otherwise.
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def previous_changes_include?(attr_name)
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previous_changes.include?(attr_name)
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end
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# Removes current changes and makes them accessible through +previous_changes+.
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def changes_applied # :doc:
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@previously_changed = changes
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@changed_attributes = ActiveSupport::HashWithIndifferentAccess.new
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end
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# Clears all dirty data: current changes and previous changes.
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def clear_changes_information # :doc:
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@previously_changed = ActiveSupport::HashWithIndifferentAccess.new
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@changed_attributes = ActiveSupport::HashWithIndifferentAccess.new
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end
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# Handles <tt>*_change</tt> for +method_missing+.
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def attribute_change(attr)
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[changed_attributes[attr], __send__(attr)] if attribute_changed?(attr)
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end
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# Handles <tt>*_previous_change</tt> for +method_missing+.
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def attribute_previous_change(attr)
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previous_changes[attr] if attribute_previously_changed?(attr)
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end
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# Handles <tt>*_will_change!</tt> for +method_missing+.
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def attribute_will_change!(attr)
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return if attribute_changed?(attr)
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begin
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value = __send__(attr)
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value = value.duplicable? ? value.clone : value
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rescue TypeError, NoMethodError
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end
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set_attribute_was(attr, value)
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end
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# Handles <tt>restore_*!</tt> for +method_missing+.
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def restore_attribute!(attr)
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if attribute_changed?(attr)
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__send__("#{attr}=", changed_attributes[attr])
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clear_attribute_changes([attr])
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end
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end
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# This is necessary because `changed_attributes` might be overridden in
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# other implementations (e.g. in `ActiveRecord`)
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alias_method :attributes_changed_by_setter, :changed_attributes # :nodoc:
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# Force an attribute to have a particular "before" value
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def set_attribute_was(attr, old_value)
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attributes_changed_by_setter[attr] = old_value
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end
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# Remove changes information for the provided attributes.
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def clear_attribute_changes(attributes) # :doc:
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attributes_changed_by_setter.except!(*attributes)
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end
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end
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end
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