Module | ActiveRecord::Dirty |
In: |
vendor/rails/activerecord/lib/active_record/dirty.rb
|
Track unsaved attribute changes.
A newly instantiated object is unchanged:
person = Person.find_by_name('uncle bob') person.changed? # => false
Change the name:
person.name = 'Bob' person.changed? # => true person.name_changed? # => true person.name_was # => 'uncle bob' person.name_change # => ['uncle bob', 'Bob'] person.name = 'Bill' person.name_change # => ['uncle bob', 'Bill']
Save the changes:
person.save person.changed? # => false person.name_changed? # => false
Assigning the same value leaves the attribute unchanged:
person.name = 'Bill' person.name_changed? # => false person.name_change # => nil
Which attributes have changed?
person.name = 'bob' person.changed # => ['name'] person.changes # => { 'name' => ['Bill', 'bob'] }
Before modifying an attribute in-place:
person.name_will_change! person.name << 'by' person.name_change # => ['uncle bob', 'uncle bobby']
# File vendor/rails/activerecord/lib/active_record/dirty.rb, line 37 37: def self.included(base) 38: base.attribute_method_suffix '_changed?', '_change', '_will_change!', '_was' 39: base.alias_method_chain :write_attribute, :dirty 40: base.alias_method_chain :save, :dirty 41: base.alias_method_chain :save!, :dirty 42: base.alias_method_chain :update, :dirty 43: base.alias_method_chain :reload, :dirty 44: 45: base.superclass_delegating_accessor :partial_updates 46: base.partial_updates = true 47: end
Do any attributes have unsaved changes?
person.changed? # => false person.name = 'bob' person.changed? # => true
# File vendor/rails/activerecord/lib/active_record/dirty.rb, line 53 53: def changed? 54: !changed_attributes.empty? 55: end
Map of changed attrs => [original value, new value]
person.changes # => {} person.name = 'bob' person.changes # => { 'name' => ['bill', 'bob'] }
# File vendor/rails/activerecord/lib/active_record/dirty.rb, line 69 69: def changes 70: changed.inject({}) { |h, attr| h[attr] = attribute_change(attr); h } 71: end