ActiveModel::AttributeAssignment
Methods
A
Instance Public methods
assign_attributes(new_attributes)

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'

Source: show | on GitHub 

# File activemodel/lib/active_model/attribute_assignment.rb, line 26
def assign_attributes(new_attributes)
  if !new_attributes.respond_to?(:stringify_keys)
    raise ArgumentError, "When assigning attributes, you must pass a hash as an argument."
  end
  return if new_attributes.nil? || new_attributes.empty?

  attributes = new_attributes.stringify_keys
  _assign_attributes(sanitize_for_mass_assignment(attributes))
end