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::Dirtyin your object. -
Call
define_attribute_methodspassing each method you want to track. -
Call
*_will_change!before each change to the tracked attribute. -
Call
changes_appliedafter the changes are persisted. -
Call
clear_changes_informationwhen you want to reset the changes information. -
Call
restore_attributeswhen you want to restore previous data.
A minimal implementation could be:
class Person include ActiveModel::Dirty define_attribute_methods :name def initialize @name = nil end 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! # get the values from the persistence layer clear_changes_information end def rollback! restore_attributes end end
A newly instantiated Person object is unchanged:
person = Person.new person.changed? # => false
Change the name:
person.name = 'Bob' person.changed? # => true person.name_changed? # => true person.name_changed?(from: nil, to: "Bob") # => true person.name_was # => nil person.name_change # => [nil, "Bob"] person.name = 'Bill' person.name_change # => [nil, "Bill"]
Save the changes:
person.save person.changed? # => false person.name_changed? # => false
Reset the changes:
person.previous_changes # => {"name" => [nil, "Bill"]} person.name_previously_changed? # => true person.name_previously_changed?(from: nil, to: "Bill") # => true person.name_previous_change # => [nil, "Bill"] person.name_previously_was # => nil person.reload! person.previous_changes # => {}
Rollback the changes:
person.name = "Uncle Bob" person.rollback! person.name # => "Bill" 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 *_will_change! to mark that the attribute is changing. Otherwise Active Model can’t track changes to in-place attributes. Note that Active Record can detect in-place modifications automatically. You do not need to call *_will_change! on Active Record models.
person.name_will_change! person.name_change # => ["Bill", "Bill"] person.name << 'y' person.name_change # => ["Bill", "Billy"]
Methods can be invoked as name_changed? or by passing an argument to the generic method attribute_changed?("name").
- #
- A
- C
- P
- R
Instance Public methods
*_change Link
This method is generated for each attribute.
Returns the old and the new value of the attribute.
person = Person.new person.name = 'Nick' person.name_change # => [nil, 'Nick']
Source: on GitHub
# File activemodel/lib/active_model/dirty.rb, line 155 *_changed? Link
This method is generated for each attribute.
Returns true if the attribute has unsaved changes.
person = Person.new person.name = 'Andrew' person.name_changed? # => true
Source: on GitHub
# File activemodel/lib/active_model/dirty.rb, line 144 *_previous_change Link
This method is generated for each attribute.
Returns the old and the new value of the attribute before the last save.
person = Person.new person.name = 'Emmanuel' person.save person.name_previous_change # => [nil, 'Emmanuel']
Source: on GitHub
# File activemodel/lib/active_model/dirty.rb, line 193 *_previously_changed?(**options) Link
This method is generated for each attribute.
Returns true if the attribute previously had unsaved changes.
person = Person.new person.name = 'Britanny' person.save person.name_previously_changed? # => true person.name_previously_changed?(from: nil, to: 'Britanny') # => true
Source: on GitHub
# File activemodel/lib/active_model/dirty.rb, line 129 *_previously_was Link
This method is generated for each attribute.
Returns the old value of the attribute before the last save.
person = Person.new person.name = 'Sage' person.save person.name_previously_was # => nil
Source: on GitHub
# File activemodel/lib/active_model/dirty.rb, line 205 *_was Link
This method is generated for each attribute.
Returns the old value of the attribute.
person = Person.new(name: 'Steph') person.name = 'Stephanie' person.name_was # => 'Steph'
Source: on GitHub
# File activemodel/lib/active_model/dirty.rb, line 182 *_will_change! Link
This method is generated for each attribute.
If an attribute is modified in-place then make use of *_will_change! to mark that the attribute is changing. Otherwise Active Model can’t track changes to in-place attributes. Note that Active Record can detect in-place modifications automatically. You do not need to call *_will_change! on Active Record models.
person = Person.new('Sandy') person.name_will_change! person.name_change # => ['Sandy', 'Sandy']
Source: on GitHub
# File activemodel/lib/active_model/dirty.rb, line 166 attribute_changed?(attr_name, **options) Link
Dispatch target for *_changed? attribute methods.
attribute_previously_changed?(attr_name, **options) Link
Dispatch target for *_previously_changed? attribute methods.
attribute_previously_was(attr_name) Link
Dispatch target for *_previously_was attribute methods.
changed() Link
Returns an array with the name of the attributes with unsaved changes.
person.changed # => [] person.name = 'bob' person.changed # => ["name"]
changed?() Link
Returns true if any of the attributes has unsaved changes, false otherwise.
person.changed? # => false person.name = 'bob' person.changed? # => true
changed_attributes() Link
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"}
changes() Link
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"] }
changes_applied() Link
Clears dirty data and moves changes to previous_changes and mutations_from_database to mutations_before_last_save respectively.
clear_*_change Link
This method is generated for each attribute.
Clears all dirty data of the attribute: current changes and previous changes.
person = Person.new(name: 'Chris') person.name = 'Jason' person.name_change # => ['Chris', 'Jason'] person.clear_name_change person.name_change # => nil
clear_attribute_changes(attr_names) Link
clear_changes_information() Link
Clears all dirty data: current changes and previous changes.
previous_changes() Link
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"]}