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after a model had been saved. This is useful in the after_save callback
when you need to know what fields changed. At present there is no way
to do this other than have code in the before_save callback that takes
a copy of the changes Map, which I thought was a bit messy.
Example.
person = Person.find_by_name('bob')
person.name = 'robert'
person.changes # => {'name' => ['bob, 'robert']}
person.save
person.changes # => {}
person.previous_changes # => {'name' => ['bob, 'robert']}
person.reload
person.previous_changes # => {}
Signed-off-by: Joshua Peek <josh@joshpeek.com>
126 lines
3.8 KiB
Ruby
126 lines
3.8 KiB
Ruby
module ActiveModel
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# Track unsaved attribute changes.
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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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# Resetting an attribute returns it to its original state:
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# person.reset_name! # => 'Bill'
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# person.changed? # => false
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# person.name_changed? # => false
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# person.name # => 'Bill'
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#
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# Before modifying an attribute in-place:
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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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changed.inject({}) { |h, attr| h[attr] = attribute_change(attr); h }
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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_attributes
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end
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private
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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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# Map of fields that were changed when the model was saved
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def previously_changed_attributes
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@previously_changed || {}
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end
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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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