save_if.rb

module SaveIf
  def update_if!(constraints, attributes)
    if destroyed?
      raise ActiveRecord::ActiveRecordError, 'cannot update a destroyed record'
    end

    update_if(constraints, attributes) ||
      raise(ActiveRecord::StaleObjectError.new(self, 'update'))
  end

  def update_if(constraints, attributes)
    save_if(constraints) { assign_attributes(attributes) }
  end

  def save_if!(constraints)
    if destroyed?
      raise ActiveRecord::ActiveRecordError, 'cannot update a destroyed record'
    end

    save_if(constraints) ||
      raise(ActiveRecord::StaleObjectError.new(self, 'update'))
  end

  def save_if(constraints)
    if new_record?
      raise ActiveRecord::ActiveRecordError, 'cannot update a new record'
    end

    _raise_readonly_record_error if readonly?
    return false if destroyed?
    @_save_if_constraints = constraints.stringify_keys
    with_transaction_returning_status do
      yield if block_given?
      _update_record == 1
    end
  ensure
    @_save_if_constraints = nil
  end

  private

  def _query_constraints_hash
    return super unless @_save_if_constraints
    @_save_if_constraints.merge(super)
  end
end