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167 lines
4.7 KiB
Ruby
167 lines
4.7 KiB
Ruby
require 'active_model/attribute_methods'
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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 to implement ActiveModel::Dirty are to:
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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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#
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# If you wish to also track previous changes on save or update, you need to
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# add
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#
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# @previously_changed = changes
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#
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# inside of your save or update method.
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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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#
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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 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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# @previously_changed = changes
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# @changed_attributes.clear
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# end
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#
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# end
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#
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# == Examples:
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#
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# A newly instantiated object is unchanged:
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# person = Person.find_by_name('Uncle Bob')
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# person.changed? # => false
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#
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# Change the name:
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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_was # => 'Uncle Bob'
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# person.name_change # => ['Uncle Bob', 'Bob']
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# person.name = 'Bill'
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# person.name_change # => ['Uncle Bob', 'Bill']
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#
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# Save the changes:
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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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# Assigning the same value leaves the attribute unchanged:
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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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# 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 <tt>[attribute_name]_will_change!</tt>
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# to mark that the attribute is changing. Otherwise ActiveModel can't track changes to
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# in-place attributes.
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#
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# person.name_will_change!
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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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included do
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attribute_method_suffix '_changed?', '_change', '_will_change!', '_was'
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attribute_method_affix :prefix => 'reset_', :suffix => '!'
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end
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# Do any attributes have unsaved changes?
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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.empty?
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end
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# List of attributes with unsaved changes.
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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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# Map of changed attrs => [original value, new value].
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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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HashWithIndifferentAccess[changed.map { |attr| [attr, attribute_change(attr)] }]
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end
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# Map of attributes that were changed when the model was saved.
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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
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end
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# Map of change <tt>attr => original value</tt>.
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def changed_attributes
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@changed_attributes ||= {}
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end
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private
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# Handle <tt>*_changed?</tt> for +method_missing+.
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def attribute_changed?(attr)
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changed_attributes.include?(attr)
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end
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# Handle <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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# Handle <tt>*_was</tt> for +method_missing+.
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def attribute_was(attr)
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attribute_changed?(attr) ? changed_attributes[attr] : __send__(attr)
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end
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# Handle <tt>*_will_change!</tt> for +method_missing+.
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def attribute_will_change!(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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changed_attributes[attr] = value
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end
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# Handle <tt>reset_*!</tt> for +method_missing+.
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def reset_attribute!(attr)
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__send__("#{attr}=", changed_attributes[attr]) if attribute_changed?(attr)
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end
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end
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end
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