Module: EnumField::EnumeratedAttribute

Defined in:
lib/enum_field/enumerated_attribute.rb

Overview

Easies the inclusion of enumerations as ActiveRecord columns. If you have a User AR, with a role_id column, you could do: <tt> class User

enumerated_attribute :role

end </tt>

This assumes a Role class, and will define role and role= methods in User class. These added methods expect an object of class Role, and Role should provide a find class method. You could get this by using Enumerated mixin

Similar to has_many :through in AR, it creates reader and writter methods to get enumerated atributes going through an intermediate model. For instance: <tt> class User

extend EnumField::EnumeratedAttribute

has_many_enumerated_attributes :roles, :through  => UserRole

end

class UserRole < ActiveRecord::Base

extend EnumField::EnumeratedAttribute

belongs_to :user
enumerated_attribute :role

end </tt> This assumes a Role class, the UserRole AR class is there just to persist the one-to-many relationship. This will define roles, roles=, role_ids and role_ids= methods in User class

Instance Method Summary collapse

Instance Method Details

#enumerated_attribute(name_attribute, options = {}) ⇒ Object Also known as: belongs_to_enumerated_attribute

Define an enumerated field of the AR class

  • name_attribute: the name of the field that will be added, for instance role

  • options: Valid options are:

    * +id_attribute+: the name of the AR column where the enumerated id will be save. Defaults to
  +name_attribute+ with an +_id+ suffix.
* +class+: the class that will be instantiated when +name_attribute+ method is called. Defaults to
  +name_attribute+ in camelcase form.



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# File 'lib/enum_field/enumerated_attribute.rb', line 44

def enumerated_attribute(name_attribute, options  = {})
  id_attribute = (options[:id_attribute] || "#{name_attribute}_id").to_sym
  klass = options[:class] || (options[:class_name] || name_attribute).to_s.camelcase.constantize

  define_method(name_attribute) do
    (raw = read_attribute(id_attribute)) && klass.find_by_id(raw)
  end

  define_method("#{name_attribute}=") do |value|
    write_attribute(id_attribute, value ? value.id : nil)
  end
end

#has_many_enumerated_attributes(association, options = {}) ⇒ Object

Defines a one-to-many association between an AR class and the enumerated

  • association: the name of the one-to-many association, for instance roles

  • options: Valid options are:

    * +through+ : the name of the AR class needed to persist the one-to-many association.
   Defaults to AR class in camelcase form concatenated with the enumerated class in camelcase form.
* +class+:    the enumerated class, it will be instantiated +n+ times when +association+ method is called.
   Defaults to +association+ in singular camelcase form.



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# File 'lib/enum_field/enumerated_attribute.rb', line 67

def has_many_enumerated_attributes(association, options = {})
  enum_attr = association.to_s.singularize
  klass     = options[:class]   || enum_attr.camelcase.constantize
  through   = options[:through] || (self.name + klass.name)
  self_attribute = self.name.demodulize.underscore
  association_ids = association.to_s.singularize + '_ids'
  has_many_aux = through.demodulize.underscore.pluralize

  has_many has_many_aux, {:class_name => through, :dependent => :destroy}

  define_method(association) do
    self.send(has_many_aux).map(&enum_attr.to_sym)
  end

  define_method(association.to_s + '=') do |values|
    self.send(has_many_aux + '=', values.map{|g| through.constantize.new(self_attribute => self, enum_attr => g)})
  end

  define_method(association_ids) do
     self.send(association).map(&:id)
  end

  define_method(association_ids + '=') do |values|
    self.send(has_many_aux + '=', values.map{|g| g.to_i unless g.blank?}.compact.map{|g_id| through.constantize.new(self_attribute => self, enum_attr + '_id' => g_id) })
  end
end