Module: ActiveModel::AttributeMethods::ClassMethods

Returns the original name for the alias name

Is new_name an alias?

Declares a method available for all attributes with the given prefix and suffix. Uses ActiveModel::AttributeMethods#method_missing and ActiveModel::AttributeMethods#respond_to? to rewrite the method.

#{prefix}#{attr}#{suffix}(*args, &block)

to

#{prefix}attribute#{suffix}(#{attr}, *args, &block)

An #{prefix}attribute#{suffix} instance method must exist and accept at least the attr argument.

class Person
  include ActiveModel::AttributeMethods

  attr_accessor :name
  attribute_method_affix prefix: 'reset_', suffix: '_to_default!'
  define_attribute_methods :name

  private

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

person = Person.new
person.name                         # => 'Gem'
person.reset_name_to_default!
person.name                         # => 'Default Name'

The methods ActiveModel::AttributeMethods#method_missing and ActiveModel::AttributeMethods#respond_to? of this module are invoked often in a typical rails, both of which invoke the method ActiveModel::AttributeMethods#matched_attribute_method. The latter method iterates through an array doing regular expression matches, which results in a lot of object creations. Most of the time it returns a nil match. As the match result is always the same given a method_name, this cache is used to alleviate the GC, which ultimately also speeds up the app significantly (in our case our test suite finishes 10% faster with this cache).

Declares a method available for all attributes with the given prefix. Uses ActiveModel::AttributeMethods#method_missing and ActiveModel::AttributeMethods#respond_to? to rewrite the method.

#{prefix}#{attr}(*args, &block)

to

#{prefix}attribute(#{attr}, *args, &block)

An instance method #{prefix}attribute must exist and accept at least the attr argument.

class Person
  include ActiveModel::AttributeMethods

  attr_accessor :name
  attribute_method_prefix 'clear_'
  define_attribute_methods :name

  private

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

person = Person.new
person.name = 'Bob'
person.name          # => "Bob"
person.clear_name
person.name          # => nil

Declares a method available for all attributes with the given suffix. Uses ActiveModel::AttributeMethods#method_missing and ActiveModel::AttributeMethods#respond_to? to rewrite the method.

#{attr}#{suffix}(*args, &block)

to

attribute#{suffix}(#{attr}, *args, &block)

An attribute#{suffix} instance method must exist and accept at least the attr argument.

class Person
  include ActiveModel::AttributeMethods

  attr_accessor :name
  attribute_method_suffix '_short?'
  define_attribute_methods :name

  private

  def attribute_short?(attr)
    send(attr).length < 5
  end
end

person = Person.new
person.name = 'Bob'
person.name          # => "Bob"
person.name_short?   # => true

Declares an attribute that should be prefixed and suffixed by ::ActiveModel::AttributeMethods.

To use, pass an attribute name (as string or symbol). Be sure to declare define_attribute_method after you define any prefix, suffix or affix method, or they will not hook in.

class Person
  include ActiveModel::AttributeMethods

  attr_accessor :name
  attribute_method_suffix '_short?'

  # Call to define_attribute_method must appear after the
  # attribute_method_prefix, attribute_method_suffix or
  # attribute_method_affix declarations.
  define_attribute_method :name

  private

  def attribute_short?(attr)
    send(attr).length < 5
  end
end

person = Person.new
person.name = 'Bob'
person.name        # => "Bob"
person.name_short? # => true

Declares the attributes that should be prefixed and suffixed by ::ActiveModel::AttributeMethods.

To use, pass attribute names (as strings or symbols). Be sure to declare define_attribute_methods after you define any prefix, suffix or affix methods, or they will not hook in.

class Person
  include ActiveModel::AttributeMethods

  attr_accessor :name, :age, :address
  attribute_method_prefix 'clear_'

  # Call to define_attribute_methods must appear after the
  # attribute_method_prefix, attribute_method_suffix or
  # attribute_method_affix declarations.
  define_attribute_methods :name, :age, :address

  private

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

Define a method name in mod that dispatches to send using the given extra args. This falls back on define_method and send if the given names cannot be compiled.

Removes all the previously dynamically defined methods from the class.

class Person
  include ActiveModel::AttributeMethods

  attr_accessor :name
  attribute_method_suffix '_short?'
  define_attribute_method :name

  private

  def attribute_short?(attr)
    send(attr).length < 5
  end
end

person = Person.new
person.name = 'Bob'
person.name_short? # => true

Person.undefine_attribute_methods

person.name_short? # => NoMethodError