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Module: ActiveModel::AttributeMethods::ClassMethods

Relationships & Source Files
Namespace Children
Classes:
AttributeMethodMatcher
Defined in: activemodel/lib/active_model/attribute_methods.rb

Instance Method Summary

Instance Method Details

#alias_attribute(new_name, old_name)

Allows you to make aliases for attributes.

class Person
  include ActiveModel::AttributeMethods

  attr_accessor :name
  attribute_method_suffix '_short?'
  define_attribute_methods :name

  alias_attribute :nickname, :name

  private

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

person = Person.new
person.name = 'Bob'
person.name            # => "Bob"
person.nickname        # => "Bob"
person.name_short?     # => true
person.nickname_short? # => true
[ GitHub ] 

  


# File 'activemodel/lib/active_model/attribute_methods.rb', line 208



def alias_attribute(new_name, old_name)
  self.attribute_aliases = attribute_aliases.merge(new_name.to_s => old_name.to_s)
  attribute_method_matchers.each do |matcher|
    matcher_new = matcher.method_name(new_name).to_s
    matcher_old = matcher.method_name(old_name).to_s
    define_proxy_call false, self, matcher_new, matcher_old
  end
end


  








  

    #attribute_alias(name)  
  



  

    

Returns the original name for the alias name


  



  [ GitHub ]


  

  


# File 'activemodel/lib/active_model/attribute_methods.rb', line 223



def attribute_alias(name)
  attribute_aliases[name.to_s]
end


  








  

    #attribute_alias?(new_name)  ⇒ Boolean 
  



  

    

Is new_name an alias?


  





  


  [ GitHub ]


  

  


# File 'activemodel/lib/active_model/attribute_methods.rb', line 218



def attribute_alias?(new_name)
  attribute_aliases.key? new_name.to_s
end


  








  

    #attribute_method_affix(*affixes)  
  



  

    

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'


  



  [ GitHub ]


  

  


# File 'activemodel/lib/active_model/attribute_methods.rb', line 179



def attribute_method_affix(*affixes)
  self.attribute_method_matchers += affixes.map! { |affix| AttributeMethodMatcher.new prefix: affix[:prefix], suffix: affix[:suffix] }
  undefine_attribute_methods
end


  








  

    #attribute_method_prefix(*prefixes)  
  



  

    

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


  



  [ GitHub ]


  

  


# File 'activemodel/lib/active_model/attribute_methods.rb', line 108



def attribute_method_prefix(*prefixes)
  self.attribute_method_matchers += prefixes.map! { |prefix| AttributeMethodMatcher.new prefix: prefix }
  undefine_attribute_methods
end


  








  

    #attribute_method_suffix(*suffixes)  
  



  

    

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


  



  [ GitHub ]


  

  


# File 'activemodel/lib/active_model/attribute_methods.rb', line 143



def attribute_method_suffix(*suffixes)
  self.attribute_method_matchers += suffixes.map! { |suffix| AttributeMethodMatcher.new suffix: suffix }
  undefine_attribute_methods
end


  








  

    #define_attribute_method(attr_name)  
  



  

    

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 declares.
  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


  



  [ GitHub ]


  

  


# File 'activemodel/lib/active_model/attribute_methods.rb', line 284



def define_attribute_method(attr_name)
  attribute_method_matchers.each do |matcher|
    method_name = matcher.method_name(attr_name)

    unless instance_method_already_implemented?(method_name)
      generate_method = "define_method_#{matcher.method_missing_target}"

      if respond_to?(generate_method, true)
        send(generate_method, attr_name)
      else
        define_proxy_call true, generated_attribute_methods, method_name, matcher.method_missing_target, attr_name.to_s
      end
    end
  end
  attribute_method_matchers_cache.clear
end


  








  

    #define_attribute_methods(*attr_names)  
  



  

    

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 declares.
  define_attribute_methods :name, :age, :address

  private

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


  



  [ GitHub ]


  

  


# File 'activemodel/lib/active_model/attribute_methods.rb', line 251



def define_attribute_methods(*attr_names)
  attr_names.flatten.each { |attr_name| define_attribute_method(attr_name) }
end


  








  

    #undefine_attribute_methods  
  



  

    

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


  



  [ GitHub ]


  

  


# File 'activemodel/lib/active_model/attribute_methods.rb', line 324



def undefine_attribute_methods
  generated_attribute_methods.module_eval do
    instance_methods.each { |m| undef_method(m) }
  end
  attribute_method_matchers_cache.clear
end