Module: ActiveRecord::Persistence

Extended by:
ActiveSupport::Concern
Included in:
Base
Defined in:
lib/active_record/persistence.rb

Overview

Active Record Persistence

Defined Under Namespace

Modules: ClassMethods

Instance Method Summary collapse

Instance Method Details

#becomes(klass) ⇒ Object

Returns an instance of the specified klass with the attributes of the current record. This is mostly useful in relation to single table inheritance (STI) structures where you want a subclass to appear as the superclass. This can be used along with record identification in Action Pack to allow, say, Client < Company to do something like render partial: @client.becomes(Company) to render that instance using the companies/company partial instead of clients/client.

Note: The new instance will share a link to the same attributes as the original class. Therefore the STI column value will still be the same. Any change to the attributes on either instance will affect both instances. If you want to change the STI column as well, use #becomes! instead.



713
714
715
716
717
718
719
720
721
722
723
724
725
 
# File 'lib/active_record/persistence.rb', line 713

def becomes(klass)
  became = klass.allocate

  became.send(:initialize) do |becoming|
    becoming.instance_variable_set(:@attributes, @attributes)
    becoming.instance_variable_set(:@mutations_from_database, @mutations_from_database ||= nil)
    becoming.instance_variable_set(:@new_record, new_record?)
    becoming.instance_variable_set(:@destroyed, destroyed?)
    becoming.errors.copy!(errors)
  end

  became
end

#becomes!(klass) ⇒ Object

Wrapper around #becomes that also changes the instance’s STI column value. This is especially useful if you want to persist the changed class in your database.

Note: The old instance’s STI column value will be changed too, as both objects share the same set of attributes.



733
734
735
736
737
738
739
740
741
 
# File 'lib/active_record/persistence.rb', line 733

def becomes!(klass)
  became = becomes(klass)
  sti_type = nil
  if !klass.descends_from_active_record?
    sti_type = klass.sti_name
  end
  became.public_send("#{klass.inheritance_column}=", sti_type)
  became
end

#decrement(attribute, by = 1) ⇒ Object

Initializes attribute to zero if nil and subtracts the value passed as by (default is 1). The decrement is performed directly on the underlying attribute, no setter is invoked. Only makes sense for number-based attributes. Returns self.



858
859
860
 
# File 'lib/active_record/persistence.rb', line 858

def decrement(attribute, by = 1)
  increment(attribute, -by)
end

#decrement!(attribute, by = 1, touch: nil) ⇒ Object

Wrapper around #decrement that writes the update to the database. Only attribute is updated; the record itself is not saved. This means that any other modified attributes will still be dirty. Validations and callbacks are skipped. Supports the touch option from update_counters, see that for more. Returns self.



868
869
870
 
# File 'lib/active_record/persistence.rb', line 868

def decrement!(attribute, by = 1, touch: nil)
  increment!(attribute, -by, touch: touch)
end

#delete ⇒ Object

Deletes the record in the database and freezes this instance to reflect that no changes should be made (since they can’t be persisted). Returns the frozen instance.

The row is simply removed with an SQL DELETE statement on the record’s primary key, and no callbacks are executed.

Note that this will also delete records marked as #readonly?.

To enforce the object’s before_destroy and after_destroy callbacks or any :dependent association options, use #destroy.



663
664
665
666
667
668
 
# File 'lib/active_record/persistence.rb', line 663

def delete
  _delete_row if persisted?
  @destroyed = true
  @previously_new_record = false
  freeze
end

#destroy ⇒ Object

Deletes the record in the database and freezes this instance to reflect that no changes should be made (since they can’t be persisted).

There’s a series of callbacks associated with #destroy. If the before_destroy callback throws :abort the action is cancelled and #destroy returns false. See ActiveRecord::Callbacks for further details.



677
678
679
680
681
682
683
684
685
686
687
688
 
# File 'lib/active_record/persistence.rb', line 677

def destroy
  _raise_readonly_record_error if readonly?
  destroy_associations
  @_trigger_destroy_callback = if persisted?
    destroy_row > 0
  else
    true
  end
  @destroyed = true
  @previously_new_record = false
  freeze
end

#destroy! ⇒ Object

Deletes the record in the database and freezes this instance to reflect that no changes should be made (since they can’t be persisted).

There’s a series of callbacks associated with #destroy!. If the before_destroy callback throws :abort the action is cancelled and #destroy! raises ActiveRecord::RecordNotDestroyed. See ActiveRecord::Callbacks for further details.



697
698
699
 
# File 'lib/active_record/persistence.rb', line 697

def destroy!
  destroy || _raise_record_not_destroyed
end

#destroyed? ⇒ Boolean

Returns true if this object has been destroyed, otherwise returns false.

Returns:

  • (Boolean) 


579
580
581
 
# File 'lib/active_record/persistence.rb', line 579

def destroyed?
  @destroyed
end

#increment(attribute, by = 1) ⇒ Object

Initializes attribute to zero if nil and adds the value passed as by (default is 1). The increment is performed directly on the underlying attribute, no setter is invoked. Only makes sense for number-based attributes. Returns self.



835
836
837
838
839
 
# File 'lib/active_record/persistence.rb', line 835

def increment(attribute, by = 1)
  self[attribute] ||= 0
  self[attribute] += by
  self
end

#increment!(attribute, by = 1, touch: nil) ⇒ Object

Wrapper around #increment that writes the update to the database. Only attribute is updated; the record itself is not saved. This means that any other modified attributes will still be dirty. Validations and callbacks are skipped. Supports the touch option from update_counters, see that for more. Returns self.



847
848
849
850
851
852
853
 
# File 'lib/active_record/persistence.rb', line 847

def increment!(attribute, by = 1, touch: nil)
  increment(attribute, by)
  change = public_send(attribute) - (public_send(:"#{attribute}_in_database") || 0)
  self.class.update_counters(id, attribute => change, touch: touch)
  public_send(:"clear_#{attribute}_change")
  self
end

#new_record? ⇒ Boolean

Returns true if this object hasn’t been saved yet – that is, a record for the object doesn’t exist in the database yet; otherwise, returns false.

Returns:

  • (Boolean) 


562
563
564
 
# File 'lib/active_record/persistence.rb', line 562

def new_record?
  @new_record
end

#persisted? ⇒ Boolean

Returns true if the record is persisted, i.e. it’s not a new record and it was not destroyed, otherwise returns false.

Returns:

  • (Boolean) 


585
586
587
 
# File 'lib/active_record/persistence.rb', line 585

def persisted?
  !(@new_record || @destroyed)
end

#previously_new_record? ⇒ Boolean

Returns true if this object was just created – that is, prior to the last update or delete, the object didn’t exist in the database and new_record? would have returned true.

Returns:

  • (Boolean) 


569
570
571
 
# File 'lib/active_record/persistence.rb', line 569

def previously_new_record?
  @previously_new_record
end

#previously_persisted? ⇒ Boolean

Returns true if this object was previously persisted but now it has been deleted.

Returns:

  • (Boolean) 


574
575
576
 
# File 'lib/active_record/persistence.rb', line 574

def previously_persisted?
  !new_record? && destroyed?
end

#reload(options = nil) ⇒ Object

Reloads the record from the database.

This method finds the record by its primary key (which could be assigned manually) and modifies the receiver in-place:

 = Account.new
# => #<Account id: nil, email: nil>
.id = 1
.reload
# Account Load (1.2ms)  SELECT "accounts".* FROM "accounts" WHERE "accounts"."id" = $1 LIMIT 1  [["id", 1]]
# => #<Account id: 1, email: '[email protected]'>

Attributes are reloaded from the database, and caches busted, in particular the associations cache and the QueryCache.

If the record no longer exists in the database ActiveRecord::RecordNotFound is raised. Otherwise, in addition to the in-place modification the method returns self for convenience.

The optional :lock flag option allows you to lock the reloaded record:

reload(lock: true) # reload with pessimistic locking

Reloading is commonly used in test suites to test something is actually written to the database, or when some action modifies the corresponding row in the database but not the object in memory:

assert .deposit!(25)
assert_equal 25, .credit        # check it is updated in memory
assert_equal 25, .reload.credit # check it is also persisted

Another common use case is optimistic locking handling:

def with_optimistic_retry
  begin
    yield
  rescue ActiveRecord::StaleObjectError
    begin
      # Reload lock_version in particular.
      reload
    rescue ActiveRecord::RecordNotFound
      # If the record is gone there is nothing to do.
    else
      retry
    end
  end
end



945
946
947
948
949
950
951
952
953
954
955
956
957
958
959
 
# File 'lib/active_record/persistence.rb', line 945

def reload(options = nil)
  self.class.connection.clear_query_cache

  fresh_object = if apply_scoping?(options)
    _find_record(options)
  else
    self.class.unscoped { _find_record(options) }
  end

  @association_cache = fresh_object.instance_variable_get(:@association_cache)
  @attributes = fresh_object.instance_variable_get(:@attributes)
  @new_record = false
  @previously_new_record = false
  self
end

#save(**options, &block) ⇒ Object

:call-seq:

save(**options)

Saves the model.

If the model is new, a record gets created in the database, otherwise the existing record gets updated.

By default, save always runs validations. If any of them fail the action is cancelled and #save returns false, and the record won’t be saved. However, if you supply validate: false, validations are bypassed altogether. See ActiveRecord::Validations for more information.

By default, #save also sets the updated_at/updated_on attributes to the current time. However, if you supply touch: false, these timestamps will not be updated.

There’s a series of callbacks associated with #save. If any of the before_* callbacks throws :abort the action is cancelled and #save returns false. See ActiveRecord::Callbacks for further details.

Attributes marked as readonly are silently ignored if the record is being updated.



614
615
616
617
618
 
# File 'lib/active_record/persistence.rb', line 614

def save(**options, &block)
  create_or_update(**options, &block)
rescue ActiveRecord::RecordInvalid
  false
end

#save!(**options, &block) ⇒ Object

:call-seq:

save!(**options)

Saves the model.

If the model is new, a record gets created in the database, otherwise the existing record gets updated.

By default, #save! always runs validations. If any of them fail ActiveRecord::RecordInvalid gets raised, and the record won’t be saved. However, if you supply validate: false, validations are bypassed altogether. See ActiveRecord::Validations for more information.

By default, #save! also sets the updated_at/updated_on attributes to the current time. However, if you supply touch: false, these timestamps will not be updated.

There’s a series of callbacks associated with #save!. If any of the before_* callbacks throws :abort the action is cancelled and #save! raises ActiveRecord::RecordNotSaved. See ActiveRecord::Callbacks for further details.

Attributes marked as readonly are silently ignored if the record is being updated.

Unless an error is raised, returns true.



647
648
649
 
# File 'lib/active_record/persistence.rb', line 647

def save!(**options, &block)
  create_or_update(**options, &block) || raise(RecordNotSaved.new("Failed to save the record", self))
end

#toggle(attribute) ⇒ Object

Assigns to attribute the boolean opposite of attribute?. So if the predicate returns true the attribute will become false. This method toggles directly the underlying value without calling any setter. Returns self.

Example:

user = User.first
user.banned? # => false
user.toggle(:banned)
user.banned? # => true



884
885
886
887
 
# File 'lib/active_record/persistence.rb', line 884

def toggle(attribute)
  self[attribute] = !public_send("#{attribute}?")
  self
end

#toggle!(attribute) ⇒ Object

Wrapper around #toggle that saves the record. This method differs from its non-bang version in the sense that it passes through the attribute setter. Saving is not subjected to validation checks. Returns true if the record could be saved.



893
894
895
 
# File 'lib/active_record/persistence.rb', line 893

def toggle!(attribute)
  toggle(attribute).update_attribute(attribute, self[attribute])
end

#touch(*names, time: nil) ⇒ Object

Saves the record with the updated_at/on attributes set to the current time or the time specified. Please note that no validation is performed and only the after_touch, after_commit and after_rollback callbacks are executed.

This method can be passed attribute names and an optional time argument. If attribute names are passed, they are updated along with updated_at/on attributes. If no time argument is passed, the current time is used as default.

product.touch                         # updates updated_at/on with current time
product.touch(time: Time.new(2015, 2, 16, 0, 0, 0)) # updates updated_at/on with specified time
product.touch(:designed_at)           # updates the designed_at attribute and updated_at/on
product.touch(:started_at, :ended_at) # updates started_at, ended_at and updated_at/on attributes

If used along with belongs_to then touch will invoke touch method on associated object.

class Brake < ActiveRecord::Base
  belongs_to :car, touch: true
end

class Car < ActiveRecord::Base
  belongs_to :corporation, touch: true
end

# triggers @brake.car.touch and @brake.car.corporation.touch
@brake.touch

Note that touch must be used on a persisted object, or else an ActiveRecordError will be thrown. For example:

ball = Ball.new
ball.touch(:updated_at)   # => raises ActiveRecordError



995
996
997
998
999
1000
1001
1002
1003
1004
1005
1006
1007
1008
1009
1010
1011
 
# File 'lib/active_record/persistence.rb', line 995

def touch(*names, time: nil)
  _raise_record_not_touched_error unless persisted?
  _raise_readonly_record_error if readonly?

  attribute_names = timestamp_attributes_for_update_in_model
  attribute_names |= names.map! do |name|
    name = name.to_s
    self.class.attribute_aliases[name] || name
  end unless names.empty?

  unless attribute_names.empty?
    affected_rows = _touch_row(attribute_names, time)
    @_trigger_update_callback = affected_rows == 1
  else
    true
  end
end

#update(attributes) ⇒ Object

Updates the attributes of the model from the passed-in hash and saves the record, all wrapped in a transaction. If the object is invalid, the saving will fail and false will be returned.



766
767
768
769
770
771
772
773
 
# File 'lib/active_record/persistence.rb', line 766

def update(attributes)
  # The following transaction covers any possible database side-effects of the
  # attributes assignment. For example, setting the IDs of a child collection.
  with_transaction_returning_status do
    assign_attributes(attributes)
    save
  end
end

#update!(attributes) ⇒ Object

Updates its receiver just like #update but calls #save! instead of save, so an exception is raised if the record is invalid and saving will fail.



777
778
779
780
781
782
783
784
 
# File 'lib/active_record/persistence.rb', line 777

def update!(attributes)
  # The following transaction covers any possible database side-effects of the
  # attributes assignment. For example, setting the IDs of a child collection.
  with_transaction_returning_status do
    assign_attributes(attributes)
    save!
  end
end

#update_attribute(name, value) ⇒ Object

Updates a single attribute and saves the record. This is especially useful for boolean flags on existing records. Also note that

  • Validation is skipped.

  • Callbacks are invoked.

  • updated_at/updated_on column is updated if that column is available.

  • Updates all the attributes that are dirty in this object.

This method raises an ActiveRecord::ActiveRecordError if the attribute is marked as readonly.

Also see #update_column.



755
756
757
758
759
760
761
 
# File 'lib/active_record/persistence.rb', line 755

def update_attribute(name, value)
  name = name.to_s
  verify_readonly_attribute(name)
  public_send("#{name}=", value)

  save(validate: false)
end

#update_column(name, value) ⇒ Object

Equivalent to update_columns(name => value).



787
788
789
 
# File 'lib/active_record/persistence.rb', line 787

def update_column(name, value)
  update_columns(name => value)
end

#update_columns(attributes) ⇒ Object

Updates the attributes directly in the database issuing an UPDATE SQL statement and sets them in the receiver:

user.update_columns(last_request_at: Time.current)

This is the fastest way to update attributes because it goes straight to the database, but take into account that in consequence the regular update procedures are totally bypassed. In particular:

  • Validations are skipped.

  • Callbacks are skipped.

  • updated_at/updated_on are not updated.

  • However, attributes are serialized with the same rules as ActiveRecord::Relation#update_all

This method raises an ActiveRecord::ActiveRecordError when called on new objects, or when at least one of the attributes is marked as readonly.

Raises:



807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
 
# File 'lib/active_record/persistence.rb', line 807

def update_columns(attributes)
  raise ActiveRecordError, "cannot update a new record" if new_record?
  raise ActiveRecordError, "cannot update a destroyed record" if destroyed?
  _raise_readonly_record_error if readonly?

  attributes = attributes.transform_keys do |key|
    name = key.to_s
    name = self.class.attribute_aliases[name] || name
    verify_readonly_attribute(name) || name
  end

  update_constraints = _query_constraints_hash
  attributes = attributes.each_with_object({}) do |(k, v), h|
    h[k] = @attributes.write_cast_value(k, v)
    clear_attribute_change(k)
  end

  affected_rows = self.class._update_record(
    attributes,
    update_constraints
  )

  affected_rows == 1
end