Provides a way to track changes in your object in the same way as Active Record does.
The requirements for implementing ActiveModel::Dirty are:
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 108 108: def changed 109: changed_attributes.keys 110: end
Returns true if any attribute have unsaved changes, false otherwise.
person.changed? # => false person.name = 'bob' person.changed? # => true
# File lib/active_model/dirty.rb, line 100 100: def changed? 101: changed_attributes.any? 102: end
Map of change attr => original value.
# File lib/active_model/dirty.rb, line 130 130: def changed_attributes 131: @changed_attributes ||= {} 132: 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 116 116: def changes 117: HashWithIndifferentAccess[changed.map { |attr| [attr, attribute_change(attr)] }] 118: 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 125 125: def previous_changes 126: @previously_changed 127: end
Handle *_change for method_missing.
# File lib/active_model/dirty.rb, line 142 142: def attribute_change(attr) 143: [changed_attributes[attr], __send__(attr)] if attribute_changed?(attr) 144: end
Handle *_changed? for method_missing.
# File lib/active_model/dirty.rb, line 137 137: def attribute_changed?(attr) 138: changed_attributes.include?(attr) 139: end
Handle *_was for method_missing.
# File lib/active_model/dirty.rb, line 147 147: def attribute_was(attr) 148: attribute_changed?(attr) ? changed_attributes[attr] : __send__(attr) 149: end
Handle *_will_change! for method_missing.
# File lib/active_model/dirty.rb, line 152 152: def attribute_will_change!(attr) 153: begin 154: value = __send__(attr) 155: value = value.duplicable? ? value.clone : value 156: rescue TypeError, NoMethodError 157: end 158: 159: changed_attributes[attr] = value unless changed_attributes.include?(attr) 160: end
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