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 clear_changes_information
when you want to reset the changes information.
Call restore_attributes
when 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 [attribute_name]_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 [attribute_name]_will_change!
on Active Record models.
person.name_will_change! person.name_change # => ["Bill", "Bill"] person.name << 'y' person.name_change # => ["Bill", "Billy"]
# File activemodel/lib/active_model/dirty.rb, line 173 def changed mutations_from_database.changed_attribute_names end
Returns an array with the name of the attributes with unsaved changes.
person.changed # => [] person.name = 'bob' person.changed # => ["name"]
# File activemodel/lib/active_model/dirty.rb, line 164 def changed? mutations_from_database.any_changes? end
Returns true
if any of the attributes has unsaved changes, false
otherwise.
person.changed? # => false person.name = 'bob' person.changed? # => true
# File activemodel/lib/active_model/dirty.rb, line 221 def changed_attributes mutations_from_database.changed_values 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"}
# File activemodel/lib/active_model/dirty.rb, line 231 def changes mutations_from_database.changes 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"] }
# File activemodel/lib/active_model/dirty.rb, line 150 def changes_applied unless defined?(@attributes) mutations_from_database.finalize_changes end @mutations_before_last_save = mutations_from_database forget_attribute_assignments @mutations_from_database = nil end
Clears dirty data and moves changes
to previous_changes
and mutations_from_database
to mutations_before_last_save
respectively.
# File activemodel/lib/active_model/dirty.rb, line 209 def clear_attribute_changes(attr_names) attr_names.each do |attr_name| clear_attribute_change(attr_name) end end
# File activemodel/lib/active_model/dirty.rb, line 203 def clear_changes_information @mutations_before_last_save = nil forget_attribute_assignments @mutations_from_database = nil end
Clears all dirty data: current changes and previous changes.
# File activemodel/lib/active_model/dirty.rb, line 241 def previous_changes mutations_before_last_save.changes 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"]}
# File activemodel/lib/active_model/dirty.rb, line 198 def restore_attributes(attr_names = changed) attr_names.each { |attr_name| restore_attribute!(attr_name) } end
Restore all previous data of the provided attributes.
© 2004–2021 David Heinemeier Hansson
Licensed under the MIT License.