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']
Methods
Classes and Modules
Module ActiveRecord::Dirty::ClassMethodsConstants
DIRTY_SUFFIXES | = | ['_changed?', '_change', '_will_change!', '_was'] |
Public Class methods
[ show source ]
# File activerecord/lib/active_record/dirty.rb, line 39 39: def self.included(base) 40: base.attribute_method_suffix *DIRTY_SUFFIXES 41: base.alias_method_chain :write_attribute, :dirty 42: base.alias_method_chain :save, :dirty 43: base.alias_method_chain :save!, :dirty 44: base.alias_method_chain :update, :dirty 45: base.alias_method_chain :reload, :dirty 46: 47: base.superclass_delegating_accessor :partial_updates 48: base.partial_updates = true 49: 50: base.send(:extend, ClassMethods) 51: end
Public Instance methods
List of attributes with unsaved changes.
person.changed # => [] person.name = 'bob' person.changed # => ['name']
[ show source ]
# File activerecord/lib/active_record/dirty.rb, line 65 65: def changed 66: changed_attributes.keys 67: end
Do any attributes have unsaved changes?
person.changed? # => false person.name = 'bob' person.changed? # => true
[ show source ]
# File activerecord/lib/active_record/dirty.rb, line 57 57: def changed? 58: !changed_attributes.empty? 59: end
Map of changed attrs => [original value, new value].
person.changes # => {} person.name = 'bob' person.changes # => { 'name' => ['bill', 'bob'] }
[ show source ]
# File activerecord/lib/active_record/dirty.rb, line 73 73: def changes 74: changed.inject({}) { |h, attr| h[attr] = attribute_change(attr); h } 75: end