attribute_writer_missing

Like `BasicObject#method_missing`, `#attribute_writer_missing` is invoked when `#assign_attributes` is passed an unknown attribute name.

By default, `#attribute_writer_missing` raises an UnknownAttributeError.

class Rectangle
  include ActiveModel::AttributeAssignment

  attr_accessor :length, :width

  def attribute_writer_missing(name, value)
    Rails.logger.warn "Tried to assign to unknown attribute #{name}"
  end
end

rectangle = Rectangle.new
rectangle.assign_attributes(height: 10) # => Logs "Tried to assign to unknown attribute 'height'"