Module: AttributeChoices::AttributeChoicesMacro

Defined in:
lib/attribute_choices.rb

Instance Method Summary collapse

Instance Method Details

#attribute_choices(attribute, choices, *args) ⇒ Object

Extends ActiveRecord attributes with a ‘:choices` pseudo-type that provides convenient methods for mapping each choice to its human readable form.

The arguments are:

  • attribute - The attribute whose values you want to map to display values

  • choices - Either an Array of tupples where the first value of the tupple is the attribute \

    value and the second one is the display value mapping, or a +Hash+ where the key is the \
attribute value and the value is the display value mapping.

  • options - An optional hash of options:

    • :localize - If set to true, then I18n.trasnlate is used to translate the value \

      returned by the +_display+ instance methods as well as translate the display \
values returned by the +_choices+ class method

    • :validate - If set to true, validates_inclusion_of is used to ensure that the attribute \

      only accepts the values passed in with the +choices+

For example:

class User < ActiveRecord::Base
  attribute_choices :gender,  { 'm' => "Male", 'f' => 'Female'}
  attribute_choices :age_group,  [
    ['18-24', '18 to 24 years old], 
    ['25-45', '25 to 45 years old']
  ], :localize => true, :validate => false
end

The macro adds an instance method named after the attribute, suffixed with _display (e.g. gender_display for :gender) that returns the display value of the attribute for a given value, or nil if a mapping for a value is missing.

It also adds a class method named after the attribute, suffixed with _choices (e.g. User.gender_choices for :gender) that returns an array of choices and values in a fomrat that is suitable for passing directly to the Rails select_* helpers.

NOTE: You can use a Hash for the choices argument which is converted to an Array. The order of the \ tupples of the resulting Array is only guaranteed to be preserved if you are using Ruby 1.9



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# File 'lib/attribute_choices.rb', line 45

def attribute_choices(attribute, choices, *args)

  assert_valid_attribute(attribute.to_s)

  attribute = attribute.to_sym

  options = args.extract_options!
  options.reverse_merge!(:validate => false, :localize => false)
  options.assert_valid_keys(:validate, :localize)
  
  attribute_choices_options[attribute] = options

  choices = if options[:localize]
    choices.to_a.collect {|t| [t.first, I18n.translate(t.last)]}
  else
    choices.to_a
  end

  define_method("#{attribute.to_s}_display") do
    # The local variable `choices` is saved inside this Proc
    tupple = choices.assoc(send(attribute))
    tupple && tupple.last
  end

  (class << self; self; end).send(:define_method, "#{attribute.to_s}_choices") do
    choices.collect(&:reverse)
  end

  if options[:validate]
    validates_inclusion_of attribute.to_sym, :in => choices.collect {|i| i.first}
  end

end

#attribute_choices_options ⇒ Object

:nodoc:



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# File 'lib/attribute_choices.rb', line 80

def attribute_choices_options
  @attribute_choices_options ||= {}
end