require 'active_support/hash_with_indifferent_access' require 'active_support/core_ext/object/duplicable' module ActiveModel # == Active \Model \Dirty # # 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. # * Call changes_applied after the changes are persisted. # * Call reset_changes when you want to reset the changes # information. # # 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 # # do persistence work # changes_applied # end # # def reload! # reset_changes # 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_changed?(from: "Uncle Bob", to: "Bob") # => 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 # # Reset the changes: # # person.previous_changes # => {"name" => ["Uncle Bob", "Bill"]} # person.reload! # person.previous_changes # => {} # # 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_change # => ["Bill", "Bill"] # person.name << 'y' # person.name_change # => ["Bill", "Billy"] module Dirty extend ActiveSupport::Concern include ActiveModel::AttributeMethods included do attribute_method_suffix '_changed?', '_change', '_will_change!', '_was' attribute_method_affix prefix: 'reset_', suffix: '!' end # Returns +true+ if any attribute have unsaved changes, +false+ otherwise. # # person.changed? # => false # person.name = 'bob' # person.changed? # => true def changed? changed_attributes.present? end # Returns an array with the name of the attributes with unsaved changes. # # person.changed # => [] # person.name = 'bob' # person.changed # => ["name"] def changed changed_attributes.keys end # Returns a hash of changed attributes indicating their original # and new values like attr => [original value, new value]. # # person.changes # => {} # person.name = 'bob' # person.changes # => { "name" => ["bill", "bob"] } def changes ActiveSupport::HashWithIndifferentAccess[changed.map { |attr| [attr, attribute_change(attr)] }] end # Returns a hash of attributes that were changed before the model was saved. # # person.name # => "bob" # person.name = 'robert' # person.save # person.previous_changes # => {"name" => ["bob", "robert"]} def previous_changes @previously_changed ||= {} end # Returns a hash of the attributes with unsaved changes indicating their original # values like attr => original value. # # person.name # => "bob" # person.name = 'robert' # person.changed_attributes # => {"name" => "bob"} def changed_attributes @changed_attributes ||= ActiveSupport::HashWithIndifferentAccess.new end # Handle *_changed? for +method_missing+. def attribute_changed?(attr, options = {}) #:nodoc: result = changed_attributes.include?(attr) result &&= options[:to] == __send__(attr) if options.key?(:to) result &&= options[:from] == changed_attributes[attr] if options.key?(:from) result end # Handle *_was for +method_missing+. def attribute_was(attr) # :nodoc: attribute_changed?(attr) ? changed_attributes[attr] : __send__(attr) end private # Removes current changes and makes them accessible through +previous_changes+. def changes_applied @previously_changed = changes @changed_attributes = {} end # Removes all dirty data: current changes and previous changes def reset_changes @previously_changed = {} @changed_attributes = {} end # Handle *_change for +method_missing+. def attribute_change(attr) [changed_attributes[attr], __send__(attr)] if attribute_changed?(attr) end # Handle *_will_change! for +method_missing+. def attribute_will_change!(attr) return if attribute_changed?(attr) begin value = __send__(attr) value = value.duplicable? ? value.clone : value rescue TypeError, NoMethodError end changed_attributes[attr] = value end # Handle reset_*! for +method_missing+. def reset_attribute!(attr) if attribute_changed?(attr) __send__("#{attr}=", changed_attributes[attr]) changed_attributes.delete(attr) end end end end