aboutsummaryrefslogblamecommitdiffstats
path: root/activemodel/lib/active_model/conversion.rb
blob: cdc128281770341e030dfbf457427dbe637a18b7 (plain) (tree)
1
2
3
4
5
6
7
8
9
10

                             
                  
                                
   
                                                                                 
   
                                                     

                          
                                       
   


                                                      
           
         

                             



                                                                
                   

                                 
                                                                               
                                                                             
                     
     






                                           
                                                                               
                                                                            
                                                        


                
 

                                                                                            
     


                                         



                            

           
                              
                              
              

                                  

       


                                                                                


                                         




                            


                        

           
                              
                                
                
                                                        
       
 
                                                                         
                                                                              






                                                   

                                 

       
                                
                                                                    
                                                            

                                   
                                                                                                  
                                                              



                                           

     
# frozen_string_literal: true

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 <tt>:to_model</tt> 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 <tt>:to_model</tt> 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
    #
    #     def initialize(id)
    #       @id = id
    #     end
    #   end
    #
    #   person = Person.new(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 <tt>persisted?</tt> is +false+.
    #
    #   class Person
    #     include ActiveModel::Conversion
    #     attr_accessor :id
    #
    #     def initialize(id)
    #       @id = id
    #     end
    #
    #     def persisted?
    #       true
    #     end
    #   end
    #
    #   person = Person.new(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