Active Record Persistence

Namespace

Module

Methods

Instance Public methods

becomes(klass)

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. This includes any attribute initialization done by the new instance.

If you want to change the STI column as well, use becomes! instead.

πŸ“ Source code
# File activerecord/lib/active_record/persistence.rb, line 814
    def becomes(klass)
      became = klass.allocate

      became.send(:initialize) do |becoming|
        @attributes.reverse_merge!(becoming.instance_variable_get(:@attributes))
        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
πŸ”Ž See on GitHub

becomes!(klass)

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.

πŸ“ Source code
# File activerecord/lib/active_record/persistence.rb, line 835
    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
πŸ”Ž See on GitHub

decrement(attribute, by = 1)

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.

πŸ“ Source code
# File activerecord/lib/active_record/persistence.rb, line 982
    def decrement(attribute, by = 1)
      increment(attribute, -by)
    end
πŸ”Ž See on GitHub

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

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.

πŸ“ Source code
# File activerecord/lib/active_record/persistence.rb, line 992
    def decrement!(attribute, by = 1, touch: nil)
      increment!(attribute, -by, touch: touch)
    end
πŸ”Ž See on GitHub

delete()

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.

πŸ“ Source code
# File activerecord/lib/active_record/persistence.rb, line 766
    def delete
      _delete_row if persisted?
      @destroyed = true
      @previously_new_record = false
      freeze
    end
πŸ”Ž See on GitHub

destroy()

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.

πŸ“ Source code
# File activerecord/lib/active_record/persistence.rb, line 780
    def destroy
      _raise_readonly_record_error if readonly?
      destroy_associations
      @_trigger_destroy_callback ||= persisted? && destroy_row > 0
      @destroyed = true
      @previously_new_record = false
      freeze
    end
πŸ”Ž See on GitHub

destroy!()

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.

πŸ“ Source code
# File activerecord/lib/active_record/persistence.rb, line 796
    def destroy!
      destroy || _raise_record_not_destroyed
    end
πŸ”Ž See on GitHub

destroyed?()

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

πŸ“ Source code
# File activerecord/lib/active_record/persistence.rb, line 682
    def destroyed?
      @destroyed
    end
πŸ”Ž See on GitHub

increment(attribute, by = 1)

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.

πŸ“ Source code
# File activerecord/lib/active_record/persistence.rb, line 959
    def increment(attribute, by = 1)
      self[attribute] ||= 0
      self[attribute] += by
      self
    end
πŸ”Ž See on GitHub

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

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.

πŸ“ Source code
# File activerecord/lib/active_record/persistence.rb, line 971
    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
πŸ”Ž See on GitHub

new_record?()

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.

πŸ“ Source code
# File activerecord/lib/active_record/persistence.rb, line 665
    def new_record?
      @new_record
    end
πŸ”Ž See on GitHub

persisted?()

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

πŸ“ Source code
# File activerecord/lib/active_record/persistence.rb, line 688
    def persisted?
      !(@new_record || @destroyed)
    end
πŸ”Ž See on GitHub

previously_new_record?()

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.

πŸ“ Source code
# File activerecord/lib/active_record/persistence.rb, line 672
    def previously_new_record?
      @previously_new_record
    end
πŸ”Ž See on GitHub

previously_persisted?()

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

πŸ“ Source code
# File activerecord/lib/active_record/persistence.rb, line 677
    def previously_persisted?
      !new_record? && destroyed?
    end
πŸ”Ž See on GitHub

reload(options = nil)

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

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 account.deposit!(25)
assert_equal 25, account.credit        # check it is updated in memory
assert_equal 25, account.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
πŸ“ Source code
# File activerecord/lib/active_record/persistence.rb, line 1069
    def reload(options = nil)
      self.class.connection.clear_query_cache

      fresh_object = if apply_scoping?(options)
        _find_record((options || {}).merge(all_queries: true))
      else
        self.class.unscoped { _find_record(options) }
      end

      @association_cache = fresh_object.instance_variable_get(:@association_cache)
      @association_cache.each_value { |association| association.owner = self }
      @attributes = fresh_object.instance_variable_get(:@attributes)
      @new_record = false
      @previously_new_record = false
      self
    end
πŸ”Ž See on GitHub

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.

πŸ“ Source code
# File activerecord/lib/active_record/persistence.rb, line 717
    def save(**options, &block)
      create_or_update(**options, &block)
    rescue ActiveRecord::RecordInvalid
      false
    end
πŸ”Ž See on GitHub

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.

πŸ“ Source code
# File activerecord/lib/active_record/persistence.rb, line 750
    def save!(**options, &block)
      create_or_update(**options, &block) || raise(RecordNotSaved.new("Failed to save the record", self))
    end
πŸ”Ž See on GitHub

toggle(attribute)

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
πŸ“ Source code
# File activerecord/lib/active_record/persistence.rb, line 1008
    def toggle(attribute)
      self[attribute] = !public_send("#{attribute}?")
      self
    end
πŸ”Ž See on GitHub

toggle!(attribute)

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.

πŸ“ Source code
# File activerecord/lib/active_record/persistence.rb, line 1017
    def toggle!(attribute)
      toggle(attribute).update_attribute(attribute, self[attribute])
    end
πŸ”Ž See on GitHub

touch(*names, time: nil)

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
πŸ“ Source code
# File activerecord/lib/active_record/persistence.rb, line 1120
    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 = (attribute_names | names).map! do |name|
        name = name.to_s
        name = self.class.attribute_aliases[name] || name
        verify_readonly_attribute(name)
        name
      end

      unless attribute_names.empty?
        affected_rows = _touch_row(attribute_names, time)
        @_trigger_update_callback = affected_rows == 1
      else
        true
      end
    end
πŸ”Ž See on GitHub

update(attributes)

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.

πŸ“ Source code
# File activerecord/lib/active_record/persistence.rb, line 890
    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
πŸ”Ž See on GitHub

update!(attributes)

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.

πŸ“ Source code
# File activerecord/lib/active_record/persistence.rb, line 901
    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
πŸ”Ž See on GitHub

update_attribute(name, value)

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.

πŸ“ Source code
# File activerecord/lib/active_record/persistence.rb, line 857
    def update_attribute(name, value)
      name = name.to_s
      verify_readonly_attribute(name)
      public_send("#{name}=", value)

      save(validate: false)
    end
πŸ”Ž See on GitHub

update_attribute!(name, value)

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.

If any of the before_* callbacks throws :abort the action is cancelled and update_attribute! raises ActiveRecord::RecordNotSaved. See ActiveRecord::Callbacks for further details.

πŸ“ Source code
# File activerecord/lib/active_record/persistence.rb, line 879
    def update_attribute!(name, value)
      name = name.to_s
      verify_readonly_attribute(name)
      public_send("#{name}=", value)

      save!(validate: false)
    end
πŸ”Ž See on GitHub

update_column(name, value)

Equivalent to update_columns(name => value).

πŸ“ Source code
# File activerecord/lib/active_record/persistence.rb, line 911
    def update_column(name, value)
      update_columns(name => value)
    end
πŸ”Ž See on GitHub

update_columns(attributes)

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.

πŸ“ Source code
# File activerecord/lib/active_record/persistence.rb, line 931
    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
πŸ”Ž See on GitHub