module ActiveRecord::AttributeMethods::Dirty

Active Record Attribute Methods Dirty¶ ↑

Provides a way to track changes in your Active Record models. It adds all methods from ActiveModel::Dirty and adds database-specific methods.

A newly created Person object is unchanged:

class Person < ActiveRecord::Base
end

person = Person.create(name: "Allison")
person.changed? # => false

Change the name:

person.name = 'Alice'
person.name_in_database          # => "Allison"
person.will_save_change_to_name? # => true
person.name_change_to_be_saved   # => ["Allison", "Alice"]
person.changes_to_save           # => {"name"=>["Allison", "Alice"]}

Save the changes:

person.save
person.name_in_database        # => "Alice"
person.saved_change_to_name?   # => true
person.saved_change_to_name    # => ["Allison", "Alice"]
person.name_before_last_save   # => "Allison"

Similar to ActiveModel::Dirty, methods can be invoked as saved_change_to_name? or by passing an argument to the generic method saved_change_to_attribute?("name").

Public Instance Methods

attribute_before_last_save (attr_name)

Returns the original value of an attribute before the last save.

This method is useful in after callbacks to get the original value of an attribute before the save that triggered the callbacks to run. It can be invoked as name_before_last_save instead of attribute_before_last_save("name").

# File activerecord/lib/active_record/attribute_methods/dirty.rb, line 108
def attribute_before_last_save(attr_name)
  mutations_before_last_save.original_value(attr_name.to_s)
end

attribute_change_to_be_saved (attr_name)

Returns the change to an attribute that will be persisted during the next save.

This method is useful in validations and before callbacks, to see the change to an attribute that will occur when the record is saved. It can be invoked as name_change_to_be_saved instead of attribute_change_to_be_saved("name").

If the attribute will change, the result will be an array containing the original value and the new value about to be saved.

# File activerecord/lib/active_record/attribute_methods/dirty.rb, line 152
def attribute_change_to_be_saved(attr_name)
  mutations_from_database.change_to_attribute(attr_name.to_s)
end

attribute_in_database (attr_name)

Returns the value of an attribute in the database, as opposed to the in-memory value that will be persisted the next time the record is saved.

This method is useful in validations and before callbacks, to see the original value of an attribute prior to any changes about to be saved. It can be invoked as name_in_database instead of attribute_in_database("name").

# File activerecord/lib/active_record/attribute_methods/dirty.rb, line 164
def attribute_in_database(attr_name)
  mutations_from_database.original_value(attr_name.to_s)
end

attributes_in_database ()

Returns a hash of the attributes that will change when the record is next saved.

The hash keys are the attribute names, and the hash values are the original attribute values in the database (as opposed to the in-memory values about to be saved).

# File activerecord/lib/active_record/attribute_methods/dirty.rb, line 191
def attributes_in_database
  mutations_from_database.changed_values
end

changed_attribute_names_to_save ()

Returns an array of the names of any attributes that will change when the record is next saved.

# File activerecord/lib/active_record/attribute_methods/dirty.rb, line 181
def changed_attribute_names_to_save
  mutations_from_database.changed_attribute_names
end

changes_to_save ()

Returns a hash containing all the changes that will be persisted during the next save.

# File activerecord/lib/active_record/attribute_methods/dirty.rb, line 175
def changes_to_save
  mutations_from_database.changes
end

has_changes_to_save? ()

Will the next call to save have any changes to persist?

# File activerecord/lib/active_record/attribute_methods/dirty.rb, line 169
def has_changes_to_save?
  mutations_from_database.any_changes?
end

reload (*)

reload the record and clears changed attributes.

Calls superclass method

# File activerecord/lib/active_record/attribute_methods/dirty.rb, line 63
def reload(*)
  super.tap do
    @mutations_before_last_save = nil
    @mutations_from_database = nil
  end
end

saved_change_to_attribute (attr_name)

Returns the change to an attribute during the last save. If the attribute was changed, the result will be an array containing the original value and the saved value.

This method is useful in after callbacks, to see the change in an attribute during the save that triggered the callbacks to run. It can be invoked as saved_change_to_name instead of saved_change_to_attribute("name").

# File activerecord/lib/active_record/attribute_methods/dirty.rb, line 98
def saved_change_to_attribute(attr_name)
  mutations_before_last_save.change_to_attribute(attr_name.to_s)
end

saved_change_to_attribute? (attr_name, **options)

Did this attribute change when we last saved?

This method is useful in after callbacks to determine if an attribute was changed during the save that triggered the callbacks to run. It can be invoked as saved_change_to_name? instead of saved_change_to_attribute?("name").

Options¶ ↑

from: When specified, this method will return false unless the original value is equal to the given value.
to: When specified, this method will return false unless the value will be changed to the given value.

# File activerecord/lib/active_record/attribute_methods/dirty.rb, line 86
def saved_change_to_attribute?(attr_name, **options)
  mutations_before_last_save.changed?(attr_name.to_s, **options)
end

saved_changes ()

Returns a hash containing all the changes that were just saved.

# File activerecord/lib/active_record/attribute_methods/dirty.rb, line 118
def saved_changes
  mutations_before_last_save.changes
end

saved_changes? ()

Did the last call to save have any changes to change?

# File activerecord/lib/active_record/attribute_methods/dirty.rb, line 113
def saved_changes?
  mutations_before_last_save.any_changes?
end

will_save_change_to_attribute? (attr_name, **options)

Will this attribute change the next time we save?

This method is useful in validations and before callbacks to determine if the next call to save will change a particular attribute. It can be invoked as will_save_change_to_name? instead of will_save_change_to_attribute?("name").

Options¶ ↑

from: When specified, this method will return false unless the original value is equal to the given value.
to: When specified, this method will return false unless the value will be changed to the given value.

# File activerecord/lib/active_record/attribute_methods/dirty.rb, line 138
def will_save_change_to_attribute?(attr_name, **options)
  mutations_from_database.changed?(attr_name.to_s, **options)
end