module ActiveModel::AttributeMethods

Active Model Attribute Methods¶ ↑

Provides a way to add prefixes and suffixes to your methods as well as handling the creation of ActiveRecord::Base - like class methods such as table_name.

The requirements to implement ActiveModel::AttributeMethods are to:

• include ActiveModel::AttributeMethods in your class.

• Call each of its methods you want to add, such as attribute_method_suffix or attribute_method_prefix.

• Call define_attribute_methods after the other methods are called.

• Define the various generic _attribute methods that you have declared.

• Define an attributes method which returns a hash with each attribute name in your model as hash key and the attribute value as hash value. Hash keys must be strings.

A minimal implementation could be:

class Person
  include ActiveModel::AttributeMethods

  attribute_method_affix  prefix: 'reset_', suffix: '_to_default!'
  attribute_method_suffix '_contrived?'
  attribute_method_prefix 'clear_'
  define_attribute_methods :name

  attr_accessor :name

  def attributes
    { 'name' => @name }
  end

  private
    def attribute_contrived?(attr)
      true
    end

    def clear_attribute(attr)
      send("#{attr}=", nil)
    end

    def reset_attribute_to_default!(attr)
      send("#{attr}=", 'Default Name')
    end
end

# File activemodel/lib/active_model/attribute_methods.rb, line 520
def attribute_missing(match, ...)
  __send__(match.proxy_target, match.attr_name, ...)
end

# File activemodel/lib/active_model/attribute_methods.rb, line 507
def method_missing(method, ...)
  if respond_to_without_attributes?(method, true)
    super
  else
    match = matched_attribute_method(method.name)
    match ? attribute_missing(match, ...) : super
  end
end

# File activemodel/lib/active_model/attribute_methods.rb, line 528
def respond_to?(method, include_private_methods = false)
  if super
    true
  elsif !include_private_methods && super(method, true)
    # If we're here then we haven't found among non-private methods
    # but found among all methods. Which means that the given method is private.
    false
  else
    !matched_attribute_method(method.to_s).nil?
  end
end