module ActiveModel # == Active \Model \Conversion # # Handles default conversions: to_model, to_key, to_param, and to_partial_path. # # Let's take for example this non-persisted object. # # class ContactMessage # include ActiveModel::Conversion # # # ContactMessage are never persisted in the DB # def persisted? # false # end # end # # cm = ContactMessage.new # cm.to_model == cm # => true # cm.to_key # => nil # cm.to_param # => nil # cm.to_partial_path # => "contact_messages/contact_message" module Conversion extend ActiveSupport::Concern # If your object is already designed to implement all of the \Active \Model # you can use the default :to_model implementation, which simply # returns +self+. # # class Person # include ActiveModel::Conversion # end # # person = Person.new # person.to_model == person # => true # # If your model does not act like an \Active \Model object, then you should # define :to_model yourself returning a proxy object that wraps # your object with \Active \Model compliant methods. def to_model self end # Returns an Array of all key attributes if any of the attributes is set, whether or not # the object is persisted. Returns +nil+ if there are no key attributes. # # class Person # include ActiveModel::Conversion # attr_accessor :id # end # # person = Person.create(id: 1) # person.to_key # => [1] def to_key key = respond_to?(:id) && id key ? [key] : nil end # Returns a +string+ representing the object's key suitable for use in URLs, # or +nil+ if persisted? is +false+. # # class Person # include ActiveModel::Conversion # attr_accessor :id # def persisted? # true # end # end # # person = Person.create(id: 1) # person.to_param # => "1" def to_param (persisted? && key = to_key) ? key.join("-") : nil end # Returns a +string+ identifying the path associated with the object. # ActionPack uses this to find a suitable partial to represent the object. # # class Person # include ActiveModel::Conversion # end # # person = Person.new # person.to_partial_path # => "people/person" def to_partial_path self.class._to_partial_path end module ClassMethods #:nodoc: # Provide a class level cache for #to_partial_path. This is an # internal method and should not be accessed directly. def _to_partial_path #:nodoc: @_to_partial_path ||= begin element = ActiveSupport::Inflector.underscore(ActiveSupport::Inflector.demodulize(name)) collection = ActiveSupport::Inflector.tableize(name) "#{collection}/#{element}".freeze end end end end end