Module: ActiveModel::AttributeMethods::ClassMethods

Defined in:
lib/active_model/attribute_methods.rb

Defined Under Namespace

Classes: AttributeMethodMatcher

Instance Method Summary collapse

Instance Method Details

#alias_attribute(new_name, old_name) ⇒ Object 



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# File 'lib/active_model/attribute_methods.rb', line 225

def alias_attribute(new_name, old_name)
  attribute_method_matchers.each do |matcher|
    module_eval <<-STR, __FILE__, __LINE__ + 1
      def #{matcher.method_name(new_name)}(*args)
        send(:#{matcher.method_name(old_name)}, *args)
      end
    STR
  end
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.

For example:

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)
    ...
  end
end

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



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# File 'lib/active_model/attribute_methods.rb', line 220

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

#attribute_method_prefix(*prefixes) ⇒ 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.

For example:

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 'lib/active_model/attribute_methods.rb', line 145

def attribute_method_prefix(*prefixes)
  attribute_method_matchers.concat(prefixes.map { |prefix| AttributeMethodMatcher.new :prefix => prefix })
  undefine_attribute_methods
end

#attribute_method_suffix(*suffixes) ⇒ 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.

For example:

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 'lib/active_model/attribute_methods.rb', line 182

def attribute_method_suffix(*suffixes)
  attribute_method_matchers.concat(suffixes.map { |suffix| AttributeMethodMatcher.new :suffix => suffix })
  undefine_attribute_methods
end

#attribute_methods_generated? ⇒ Boolean

Returns true if the attribute methods defined have been generated.

Returns:

  • (Boolean) 


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# File 'lib/active_model/attribute_methods.rb', line 304

def attribute_methods_generated?
  @attribute_methods_generated ||= nil
end

#define_attr_method(name, value = nil, &block) ⇒ Object

Defines an “attribute” method (like inheritance_column or table_name). A new (class) method will be created with the given name. If a value is specified, the new method will return that value (as a string). Otherwise, the given block will be used to compute the value of the method.

The original method will be aliased, with the new name being prefixed with “original_”. This allows the new method to access the original value.

Example:

class Person

  include ActiveModel::AttributeMethods

  cattr_accessor :primary_key
  cattr_accessor :inheritance_column

  define_attr_method :primary_key, "sysid"
  define_attr_method( :inheritance_column ) do
    original_inheritance_column + "_id"
  end

end

Provides you with:

AttributePerson.primary_key
# => "sysid"
AttributePerson.inheritance_column = 'address'
AttributePerson.inheritance_column
# => 'address_id'



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# File 'lib/active_model/attribute_methods.rb', line 93

def define_attr_method(name, value=nil, &block)
  sing = singleton_class
  sing.class_eval <<-eorb, __FILE__, __LINE__ + 1
    if method_defined?(:original_#{name})
      undef :original_#{name}
    end
    alias_method :original_#{name}, :#{name}
  eorb
  if block_given?
    sing.send :define_method, name, &block
  else
    # use eval instead of a block to work around a memory leak in dev
    # mode in fcgi
    sing.class_eval <<-eorb, __FILE__, __LINE__ + 1
      def #{name}; #{value.to_s.inspect}; end
    eorb
  end
end

#define_attribute_methods(attr_names) ⇒ Object

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

To use, pass in an array of 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)
    ...
  end
end



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# File 'lib/active_model/attribute_methods.rb', line 259

def define_attribute_methods(attr_names)
  return if attribute_methods_generated?
  attr_names.each do |attr_name|
    attribute_method_matchers.each do |matcher|
      unless instance_method_already_implemented?(matcher.method_name(attr_name))
        generate_method = "define_method_#{matcher.prefix}attribute#{matcher.suffix}"

        if respond_to?(generate_method)
          send(generate_method, attr_name)
        else
          method_name = matcher.method_name(attr_name)

          generated_attribute_methods.module_eval <<-STR, __FILE__, __LINE__ + 1
            if method_defined?(:#{method_name})
              undef :#{method_name}
            end
            def #{method_name}(*args)
              send(:#{matcher.method_missing_target}, '#{attr_name}', *args)
            end
          STR
        end
      end
    end
  end
  @attribute_methods_generated = true
end

#generated_attribute_methods ⇒ Object

Returns true if the attribute methods defined have been generated.



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# File 'lib/active_model/attribute_methods.rb', line 295

def generated_attribute_methods #:nodoc:
  @generated_attribute_methods ||= begin
    mod = Module.new
    include mod
    mod
  end
end

#undefine_attribute_methods ⇒ Object

Removes all the previously dynamically defined methods from the class



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# File 'lib/active_model/attribute_methods.rb', line 287

def undefine_attribute_methods
  generated_attribute_methods.module_eval do
    instance_methods.each { |m| undef_method(m) }
  end
  @attribute_methods_generated = nil
end