# module ActiveRecord::Persistence

# Active Record Persistence¶ ↑

### Public Instance Methods

becomes(klass) click to toggle source

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.

    # File lib/active_record/persistence.rb, line 226
    def becomes(klass)
      became = klass.new
      became.instance_variable_set("@attributes", @attributes)
      became.instance_variable_set("@mutation_tracker", @mutation_tracker) if defined?(@mutation_tracker)
      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

becomes!(klass) click to toggle source

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.

    # File lib/active_record/persistence.rb, line 243
    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) click to toggle source

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`.

    # File lib/active_record/persistence.rb, line 368
    def decrement(attribute, by = 1)
      increment(attribute, -by)
    end

decrement!(attribute, by = 1, touch: nil) click to toggle source

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`.

    # File lib/active_record/persistence.rb, line 378
    def decrement!(attribute, by = 1, touch: nil)
      increment!(attribute, -by, touch: touch)
    end

delete() click to toggle source

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`.

    # File lib/active_record/persistence.rb, line 177
    def delete
      self.class.delete(id) if persisted?
      @destroyed = true
      freeze
    end

destroy() click to toggle source

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.

    # File lib/active_record/persistence.rb, line 190
    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

destroy!() click to toggle source

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.

    # File lib/active_record/persistence.rb, line 210
    def destroy!
      destroy || _raise_record_not_destroyed
    end

destroyed?() click to toggle source

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

    # File lib/active_record/persistence.rb, line 91
    def destroyed?
      sync_with_transaction_state
      @destroyed
    end

increment(attribute, by = 1) click to toggle source

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`.

    # File lib/active_record/persistence.rb, line 345
    def increment(attribute, by = 1)
      self[attribute] ||= 0
      self[attribute] += by
      self
    end

increment!(attribute, by = 1, touch: nil) click to toggle source

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`.

    # File lib/active_record/persistence.rb, line 357
    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

new_record?() click to toggle source

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.

    # File lib/active_record/persistence.rb, line 85
    def new_record?
      sync_with_transaction_state
      @new_record
    end

persisted?() click to toggle source

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

    # File lib/active_record/persistence.rb, line 98
    def persisted?
      sync_with_transaction_state
      !(@new_record || @destroyed)
    end

reload(options = nil) click to toggle source

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

    # File lib/active_record/persistence.rb, line 455
    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

save(*args) click to toggle source

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.

    # File lib/active_record/persistence.rb, line 128
    def save(*args, &block)
      create_or_update(*args, &block)
    rescue ActiveRecord::RecordInvalid
      false
    end

save!(*args) click to toggle source

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.

    # File lib/active_record/persistence.rb, line 161
    def save!(*args, &block)
      create_or_update(*args, &block) || raise(RecordNotSaved.new("Failed to save the record", self))
    end

toggle(attribute) click to toggle source

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

    # File lib/active_record/persistence.rb, line 394
    def toggle(attribute)
      self[attribute] = !public_send("#{attribute}?")
      self
    end

toggle!(attribute) click to toggle source

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.

    # File lib/active_record/persistence.rb, line 403
    def toggle!(attribute)
      toggle(attribute).update_attribute(attribute, self[attribute])
    end

touch(*names, time: nil) click to toggle source

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

    # File lib/active_record/persistence.rb, line 504
        def touch(*names, time: nil)
          unless persisted?
            raise ActiveRecordError, "          cannot touch on a new or destroyed record object. Consider using
              persisted?, new_record?, or destroyed? before touching
    ".squish
          end

          time ||= current_time_from_proper_timezone
          attributes = timestamp_attributes_for_update_in_model
          attributes.concat(names)

          unless attributes.empty?
            changes = {}

            attributes.each do |column|
              column = column.to_s
              changes[column] = write_attribute(column, time)
            end

            primary_key = self.class.primary_key
            scope = self.class.unscoped.where(primary_key => _read_attribute(primary_key))

            if locking_enabled?
              locking_column = self.class.locking_column
              scope = scope.where(locking_column => _read_attribute(locking_column))
              changes[locking_column] = increment_lock
            end

            clear_attribute_changes(changes.keys)
            result = scope.update_all(changes) == 1

            if !result && locking_enabled?
              raise ActiveRecord::StaleObjectError.new(self, "touch")
            end

            @_trigger_update_callback = result
            result
          else
            true
          end
        end

update(attributes) click to toggle source

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.

    # File lib/active_record/persistence.rb, line 280
    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

Also aliased as: update_attributes
update!(attributes) click to toggle source

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.

    # File lib/active_record/persistence.rb, line 293
    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

Also aliased as: update_attributes!
update_attribute(name, value) click to toggle source

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.

    # File lib/active_record/persistence.rb, line 265
    def update_attribute(name, value)
      name = name.to_s
      verify_readonly_attribute(name)
      public_send("#{name}=", value)

      if has_changes_to_save?
        save(validate: false)
      else
        true
      end
    end

update_attributes(attributes)
Alias for: update
update_attributes!(attributes)
Alias for: update!
update_column(name, value) click to toggle source

Equivalent to `update_columns(name => value)`.

    # File lib/active_record/persistence.rb, line 305
    def update_column(name, value)
      update_columns(name => value)
    end

update_columns(attributes) click to toggle source

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.

    # File lib/active_record/persistence.rb, line 325
    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

      updated_count = self.class.unscoped.where(self.class.primary_key => id).update_all(attributes)

      attributes.each do |k, v|
        raw_write_attribute(k, v)
      end

      updated_count == 1
    end

### Private Instance Methods

_create_record(attribute_names = self.attribute_names) { |self| ... } click to toggle source

Creates a record with values matching those of the instance attributes and returns its id.

    # File lib/active_record/persistence.rb, line 586
    def _create_record(attribute_names = self.attribute_names)
      attributes_values = arel_attributes_with_values_for_create(attribute_names)

      new_id = self.class.unscoped.insert attributes_values
      self.id ||= new_id if self.class.primary_key

      @new_record = false

      yield(self) if block_given?

      id
    end

_raise_readonly_record_error() click to toggle source

    # File lib/active_record/persistence.rb, line 614
    def _raise_readonly_record_error
      raise ReadOnlyRecord, "#{self.class} is marked as readonly"
    end

_raise_record_not_destroyed() click to toggle source

    # File lib/active_record/persistence.rb, line 603
    def _raise_record_not_destroyed
      @_association_destroy_exception ||= nil
      raise @_association_destroy_exception || RecordNotDestroyed.new("Failed to destroy the record", self)
    ensure
      @_association_destroy_exception = nil
    end

_update_record(attribute_names = self.attribute_names) { |self| ... } click to toggle source

Updates the associated record with values matching those of the instance attributes. Returns the number of affected rows.

    # File lib/active_record/persistence.rb, line 569
    def _update_record(attribute_names = self.attribute_names)
      attributes_values = arel_attributes_with_values_for_update(attribute_names)
      if attributes_values.empty?
        rows_affected = 0
        @_trigger_update_callback = true
      else
        rows_affected = self.class.unscoped._update_record attributes_values, id, id_in_database
        @_trigger_update_callback = rows_affected > 0
      end

      yield(self) if block_given?

      rows_affected
    end

belongs_to_touch_method() click to toggle source

    # File lib/active_record/persistence.rb, line 610
    def belongs_to_touch_method
      :touch
    end

create_or_update(*args, &block) click to toggle source

    # File lib/active_record/persistence.rb, line 561
    def create_or_update(*args, &block)
      _raise_readonly_record_error if readonly?
      result = new_record? ? _create_record(&block) : _update_record(*args, &block)
      result != false
    end

destroy_associations() click to toggle source

A hook to be overridden by association modules.

    # File lib/active_record/persistence.rb, line 550
    def destroy_associations
    end

destroy_row() click to toggle source

    # File lib/active_record/persistence.rb, line 553
    def destroy_row
      relation_for_destroy.delete_all
    end

relation_for_destroy() click to toggle source

    # File lib/active_record/persistence.rb, line 557
    def relation_for_destroy
      self.class.unscoped.where(self.class.primary_key => id)
    end

verify_readonly_attribute(name) click to toggle source

    # File lib/active_record/persistence.rb, line 599
    def verify_readonly_attribute(name)
      raise ActiveRecordError, "#{name} is marked as readonly" if self.class.readonly_attributes.include?(name)
    end