Module: ActiveModel::AttributeMethods::ClassMethods

Defined in:
activemodel/lib/active_model/attribute_methods.rb

Defined Under Namespace

Classes: AttributeMethodPattern

Instance Method Summary collapse

Instance Method Details

#alias_attribute(new_name, old_name) ⇒ Object

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



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# File 'activemodel/lib/active_model/attribute_methods.rb', line 203

def alias_attribute(new_name, old_name)
  old_name = old_name.to_s
  new_name = new_name.to_s
  self.attribute_aliases = attribute_aliases.merge(new_name => old_name)
  aliases_by_attribute_name[old_name] << new_name
  eagerly_generate_alias_attribute_methods(new_name, old_name)
end

#alias_attribute_method_definition(code_generator, pattern, new_name, old_name) ⇒ Object

:nodoc:



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# File 'activemodel/lib/active_model/attribute_methods.rb', line 226

def alias_attribute_method_definition(code_generator, pattern, new_name, old_name) # :nodoc:
  method_name = pattern.method_name(new_name).to_s
  target_name = pattern.method_name(old_name).to_s
  parameters = pattern.parameters

  mangled_name = build_mangled_name(target_name)

  call_args = []
  call_args << parameters if parameters

  define_call(code_generator, method_name, target_name, mangled_name, parameters, call_args, namespace: :alias_attribute, as: method_name)
end

#aliases_by_attribute_name ⇒ Object

:nodoc:



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# File 'activemodel/lib/active_model/attribute_methods.rb', line 382

def aliases_by_attribute_name # :nodoc:
  @aliases_by_attribute_name ||= Hash.new { |h, k| h[k] = [] }
end

#attribute_alias(name) ⇒ Object

Returns the original name for the alias name



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# File 'activemodel/lib/active_model/attribute_methods.rb', line 245

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

#attribute_alias?(new_name) ⇒ Boolean

Is new_name an alias?

Returns:

  • (Boolean) 


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# File 'activemodel/lib/active_model/attribute_methods.rb', line 240

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

#attribute_method_affix(*affixes) ⇒ Object

Declares a method available for all attributes with the given prefix and suffix. Uses method_missing and 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'



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# File 'activemodel/lib/active_model/attribute_methods.rb', line 175

def attribute_method_affix(*affixes)
  self.attribute_method_patterns += affixes.map! { |affix| AttributeMethodPattern.new(**affix) }
  undefine_attribute_methods
end

#attribute_method_prefix(*prefixes, parameters: nil) ⇒ Object

Declares a method available for all attributes with the given prefix. Uses method_missing and 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



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# File 'activemodel/lib/active_model/attribute_methods.rb', line 106

def attribute_method_prefix(*prefixes, parameters: nil)
  self.attribute_method_patterns += prefixes.map! { |prefix| AttributeMethodPattern.new(prefix: prefix, parameters: parameters) }
  undefine_attribute_methods
end

#attribute_method_suffix(*suffixes, parameters: nil) ⇒ Object

Declares a method available for all attributes with the given suffix. Uses method_missing and 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



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# File 'activemodel/lib/active_model/attribute_methods.rb', line 140

def attribute_method_suffix(*suffixes, parameters: nil)
  self.attribute_method_patterns += suffixes.map! { |suffix| AttributeMethodPattern.new(suffix: suffix, parameters: parameters) }
  undefine_attribute_methods
end

#define_attribute_method(attr_name, _owner: generated_attribute_methods, as: attr_name) ⇒ Object

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



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# File 'activemodel/lib/active_model/attribute_methods.rb', line 311

def define_attribute_method(attr_name, _owner: generated_attribute_methods, as: attr_name)
  ActiveSupport::CodeGenerator.batch(_owner, __FILE__, __LINE__) do |owner|
    attribute_method_patterns.each do |pattern|
      define_attribute_method_pattern(pattern, attr_name, owner: owner, as: as)
    end
    attribute_method_patterns_cache.clear
  end
end

#define_attribute_method_pattern(pattern, attr_name, owner:, as:, override: false) ⇒ Object

:nodoc:



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# File 'activemodel/lib/active_model/attribute_methods.rb', line 320

def define_attribute_method_pattern(pattern, attr_name, owner:, as:, override: false) # :nodoc:
  canonical_method_name = pattern.method_name(attr_name)
  public_method_name = pattern.method_name(as)

  # If defining a regular attribute method, we don't override methods that are explicitly
  # defined in parent classes.
  if instance_method_already_implemented?(public_method_name)
    # However, for `alias_attribute`, we always define the method.
    # We check for override second because `instance_method_already_implemented?`
    # also check for dangerous methods.
    return unless override
  end

  generate_method = "define_method_#{pattern.proxy_target}"

  if respond_to?(generate_method, true)
    send(generate_method, attr_name.to_s, owner: owner, as: as)
  else
    define_proxy_call(
      owner,
      canonical_method_name,
      pattern.proxy_target,
      pattern.parameters,
      attr_name.to_s,
      namespace: :active_model_proxy,
      as: public_method_name
    )
  end
end

#define_attribute_methods(*attr_names) ⇒ Object

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



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# File 'activemodel/lib/active_model/attribute_methods.rb', line 272

def define_attribute_methods(*attr_names)
  ActiveSupport::CodeGenerator.batch(generated_attribute_methods, __FILE__, __LINE__) do |owner|
    attr_names.flatten.each do |attr_name|
      define_attribute_method(attr_name, _owner: owner)
      aliases_by_attribute_name[attr_name.to_s].each do |aliased_name|
        generate_alias_attribute_methods owner, aliased_name, attr_name
      end
    end
  end
end

#eagerly_generate_alias_attribute_methods(new_name, old_name) ⇒ Object

:nodoc:



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# File 'activemodel/lib/active_model/attribute_methods.rb', line 211

def eagerly_generate_alias_attribute_methods(new_name, old_name) # :nodoc:
  ActiveSupport::CodeGenerator.batch(generated_attribute_methods, __FILE__, __LINE__) do |code_generator|
    generate_alias_attribute_methods(code_generator, new_name, old_name)
  end
end

#generate_alias_attribute_methods(code_generator, new_name, old_name) ⇒ Object

:nodoc:



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# File 'activemodel/lib/active_model/attribute_methods.rb', line 217

def generate_alias_attribute_methods(code_generator, new_name, old_name) # :nodoc:
  ActiveSupport::CodeGenerator.batch(code_generator, __FILE__, __LINE__) do |owner|
    attribute_method_patterns.each do |pattern|
      alias_attribute_method_definition(code_generator, pattern, new_name, old_name)
    end
    attribute_method_patterns_cache.clear
  end
end

#undefine_attribute_methods ⇒ Object

Removes all the previously dynamically defined methods from the class, including alias attribute methods.

class Person
  include ActiveModel::AttributeMethods

  attr_accessor :name
  attribute_method_suffix '_short?'
  define_attribute_method :name
  alias_attribute :first_name, :name

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

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

Person.undefine_attribute_methods

person.name_short? # => NoMethodError
person.first_name  # => NoMethodError



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# File 'activemodel/lib/active_model/attribute_methods.rb', line 375

def undefine_attribute_methods
  generated_attribute_methods.module_eval do
    undef_method(*instance_methods)
  end
  attribute_method_patterns_cache.clear
end