module ActiveModel::AttributeAssignment

Allows you to set all the attributes by passing in a hash of attributes with keys matching the attribute names.

If the passed hash responds to permitted? method and the return value of this method is false an ActiveModel::ForbiddenAttributesError exception is raised.

class Cat
  include ActiveModel::AttributeAssignment
  attr_accessor :name, :status
end

cat = Cat.new
cat.assign_attributes(name: "Gorby", status: "yawning")
cat.name # => 'Gorby'
cat.status # => 'yawning'
cat.assign_attributes(status: "sleeping")
cat.name # => 'Gorby'
cat.status # => 'sleeping'

# File activemodel/lib/active_model/attribute_assignment.rb, line 28
def assign_attributes(new_attributes)
  unless new_attributes.respond_to?(:each_pair)
    raise ArgumentError, "When assigning attributes, you must pass a hash as an argument, #{new_attributes.class} passed."
  end
  return if new_attributes.empty?

  _assign_attributes(sanitize_for_mass_assignment(new_attributes))
end

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'"

# File activemodel/lib/active_model/attribute_assignment.rb, line 56
def attribute_writer_missing(name, value)
  raise UnknownAttributeError.new(self, name)
end