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/Ruby on Rails 5.2

module ActiveRecord::Persistence

Active Record Persistence

Public Instance Methods

becomes(klass) Show source
# File activerecord/lib/active_record/persistence.rb, line 370
def becomes(klass)
  became = klass.allocate
  became.send(:initialize)
  became.instance_variable_set("@attributes", @attributes)
  became.instance_variable_set("@mutations_from_database", @mutations_from_database ||= nil)
  became.instance_variable_set("@changed_attributes", attributes_changed_by_setter)
  became.instance_variable_set("@new_record", new_record?)
  became.instance_variable_set("@destroyed", destroyed?)
  became.errors.copy!(errors)
  became
end

Returns an instance of the specified klass with the attributes of the current record. This is mostly useful in relation to single-table inheritance 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.

becomes!(klass) Show source
# File activerecord/lib/active_record/persistence.rb, line 388
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

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.

decrement(attribute, by = 1) Show source
# File activerecord/lib/active_record/persistence.rb, line 513
def decrement(attribute, by = 1)
  increment(attribute, -by)
end

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.

decrement!(attribute, by = 1, touch: nil) Show source
# File activerecord/lib/active_record/persistence.rb, line 523
def decrement!(attribute, by = 1, touch: nil)
  increment!(attribute, -by, touch: touch)
end

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.

delete() Show source
# File activerecord/lib/active_record/persistence.rb, line 321
def delete
  _delete_row if persisted?
  @destroyed = true
  freeze
end

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.

destroy() Show source
# File activerecord/lib/active_record/persistence.rb, line 334
def destroy
  _raise_readonly_record_error if readonly?
  destroy_associations
  self.class.connection.add_transaction_record(self)
  @_trigger_destroy_callback = if persisted?
    destroy_row > 0
  else
    true
  end
  @destroyed = true
  freeze
end

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.

destroy!() Show source
# File activerecord/lib/active_record/persistence.rb, line 354
def destroy!
  destroy || _raise_record_not_destroyed
end

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.

destroyed?() Show source
# File activerecord/lib/active_record/persistence.rb, line 235
def destroyed?
  sync_with_transaction_state
  @destroyed
end

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

increment(attribute, by = 1) Show source
# File activerecord/lib/active_record/persistence.rb, line 490
def increment(attribute, by = 1)
  self[attribute] ||= 0
  self[attribute] += by
  self
end

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.

increment!(attribute, by = 1, touch: nil) Show source
# File activerecord/lib/active_record/persistence.rb, line 502
def increment!(attribute, by = 1, touch: nil)
  increment(attribute, by)
  change = public_send(attribute) - (attribute_in_database(attribute.to_s) || 0)
  self.class.update_counters(id, attribute => change, touch: touch)
  clear_attribute_change(attribute) # eww
  self
end

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.

new_record?() Show source
# File activerecord/lib/active_record/persistence.rb, line 229
def new_record?
  sync_with_transaction_state
  @new_record
end

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.

persisted?() Show source
# File activerecord/lib/active_record/persistence.rb, line 242
def persisted?
  sync_with_transaction_state
  !(@new_record || @destroyed)
end

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

reload(options = nil) Show source
# File activerecord/lib/active_record/persistence.rb, line 600
def reload(options = nil)
  self.class.connection.clear_query_cache

  fresh_object =
    if options && options[:lock]
      self.class.unscoped { self.class.lock(options[:lock]).find(id) }
    else
      self.class.unscoped { self.class.find(id) }
    end

  @attributes = fresh_object.instance_variable_get("@attributes")
  @new_record = false
  self
end

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
save(*args) Show source
# File activerecord/lib/active_record/persistence.rb, line 272
def save(*args, &block)
  create_or_update(*args, &block)
rescue ActiveRecord::RecordInvalid
  false
end

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.

save!(*args) Show source
# File activerecord/lib/active_record/persistence.rb, line 305
def save!(*args, &block)
  create_or_update(*args, &block) || raise(RecordNotSaved.new("Failed to save the record", self))
end

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.

toggle(attribute) Show source
# File activerecord/lib/active_record/persistence.rb, line 539
def toggle(attribute)
  self[attribute] = !public_send("#{attribute}?")
  self
end

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
toggle!(attribute) Show source
# File activerecord/lib/active_record/persistence.rb, line 548
def toggle!(attribute)
  toggle(attribute).update_attribute(attribute, self[attribute])
end

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.

touch(*names, time: nil) Show source
# File activerecord/lib/active_record/persistence.rb, line 649
    def touch(*names, time: nil)
      unless persisted?
        raise ActiveRecordError, <<-MSG.squish
          cannot touch on a new or destroyed record object. Consider using
          persisted?, new_record?, or destroyed? before touching
        MSG
      end

      attribute_names = timestamp_attributes_for_update_in_model
      attribute_names |= names.map(&:to_s)

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

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
update(attributes) Show source
# File activerecord/lib/active_record/persistence.rb, line 421
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

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.

Also aliased as: update_attributes
update!(attributes) Show source
# File activerecord/lib/active_record/persistence.rb, line 434
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

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.

Also aliased as: update_attributes!
update_attribute(name, value) Show source
# File activerecord/lib/active_record/persistence.rb, line 410
def update_attribute(name, value)
  name = name.to_s
  verify_readonly_attribute(name)
  public_send("#{name}=", value)

  save(validate: false)
end

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.

update_attributes(attributes)
Alias for: update
update_attributes!(attributes)
Alias for: update!
update_column(name, value) Show source
# File activerecord/lib/active_record/persistence.rb, line 446
def update_column(name, value)
  update_columns(name => value)
end

Equivalent to update_columns(name => value).

update_columns(attributes) Show source
# File activerecord/lib/active_record/persistence.rb, line 466
def update_columns(attributes)
  raise ActiveRecordError, "cannot update a new record" if new_record?
  raise ActiveRecordError, "cannot update a destroyed record" if destroyed?

  attributes.each_key do |key|
    verify_readonly_attribute(key.to_s)
  end

  id_in_database = self.id_in_database
  attributes.each do |k, v|
    write_attribute_without_type_cast(k, v)
  end

  affected_rows = self.class._update_record(
    attributes,
    self.class.primary_key => id_in_database
  )

  affected_rows == 1
end

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.

© 2004–2018 David Heinemeier Hansson
Licensed under the MIT License.