Provides a way to track changes in your object in the same way as Active Record does.
The requirements to implement ActiveModel::Dirty are to:
include ActiveModel::Dirty in your object
Call define_attribute_methods passing each method you want to track
Call attr_name_will_change! before each change to the tracked attribute
If you wish to also track previous changes on save or update, you need to add
@previously_changed = changes
inside of your save or update method.
A minimal implementation could be:
class Person include ActiveModel::Dirty define_attribute_methods [:name] def name @name end def name=(val) name_will_change! unless val == @name @name = val end def save @previously_changed = changes @changed_attributes.clear end end
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'] }
If an attribute is modified in-place then make use of [attribute_name]_will_change! to mark that the attribute is changing. Otherwise ActiveModel can’t track changes to in-place attributes.
person.name_will_change! person.name << 'y' person.name_change # => ['Bill', 'Billy']
List of attributes with unsaved changes.
person.changed # => [] person.name = 'bob' person.changed # => ['name']
# File lib/active_model/dirty.rb, line 109 109: def changed 110: changed_attributes.keys 111: end
Do any attributes have unsaved changes?
person.changed? # => false person.name = 'bob' person.changed? # => true
# File lib/active_model/dirty.rb, line 101 101: def changed? 102: !changed_attributes.empty? 103: end
Map of change attr => original value.
# File lib/active_model/dirty.rb, line 131 131: def changed_attributes 132: @changed_attributes ||= {} 133: end
Map of changed attrs => [original value, new value].
person.changes # => {} person.name = 'bob' person.changes # => { 'name' => ['bill', 'bob'] }
# File lib/active_model/dirty.rb, line 117 117: def changes 118: changed.inject(HashWithIndifferentAccess.new){ |h, attr| h[attr] = attribute_change(attr); h } 119: end
Map of attributes that were changed when the model was saved.
person.name # => 'bob' person.name = 'robert' person.save person.previous_changes # => {'name' => ['bob, 'robert']}
# File lib/active_model/dirty.rb, line 126 126: def previous_changes 127: @previously_changed 128: end
Handle *_change for method_missing.
# File lib/active_model/dirty.rb, line 143 143: def attribute_change(attr) 144: [changed_attributes[attr], __send__(attr)] if attribute_changed?(attr) 145: end
Handle *_changed? for method_missing.
# File lib/active_model/dirty.rb, line 138 138: def attribute_changed?(attr) 139: changed_attributes.include?(attr) 140: end
Handle *_was for method_missing.
# File lib/active_model/dirty.rb, line 148 148: def attribute_was(attr) 149: attribute_changed?(attr) ? changed_attributes[attr] : __send__(attr) 150: end
Handle *_will_change! for method_missing.
# File lib/active_model/dirty.rb, line 153 153: def attribute_will_change!(attr) 154: begin 155: value = __send__(attr) 156: value = value.duplicable? ? value.clone : value 157: rescue TypeError, NoMethodError 158: end 159: 160: changed_attributes[attr] = value 161: end
Disabled; run with --debug to generate this.
Generated with the Darkfish Rdoc Generator 1.1.6.