Polymorphic URL helpers are methods for smart resolution to a named route call when given an Active Record model instance. They are to be used in combination with ActionController::Resources.

These methods are useful when you want to generate correct URL or path to a RESTful resource without having to know the exact type of the record in question.

Nested resources and/or namespaces are also supported, as illustrated in the example: 

  polymorphic_url([:admin, @article, @comment])

results in: 

  admin_article_comment_url(@article, @comment)

Usage within the framework

Polymorphic URL helpers are used in a number of places throughout the Rails framework:

  • url_for, so you can use it with a record as the argument, e.g. url_for(@article);
  • ActionView::Helpers::FormHelper uses polymorphic_path, so you can write form_for(@article) without having to specify :url parameter for the form action;
  • redirect_to (which, in fact, uses url_for) so you can write redirect_to(post) in your controllers;
  • ActionView::Helpers::AtomFeedHelper, so you don‘t have to explicitly specify URLs for feed entries.

Prefixed polymorphic helpers

In addition to polymorphic_url and polymorphic_path methods, a number of prefixed helpers are available as a shorthand to :action => "…" in options. Those are:

  • edit_polymorphic_url, edit_polymorphic_path
  • new_polymorphic_url, new_polymorphic_path

Example usage: 

  edit_polymorphic_path(@post)              # => "/posts/1/edit"
  polymorphic_path(@post, :format => :pdf)  # => "/posts/1.pdf"
Methods
Public Instance methods
formatted_polymorphic_path(record_or_hash, options = {})

[ show source ]

     # File actionpack/lib/action_controller/polymorphic_routes.rb, line 140
140:     def formatted_polymorphic_path(record_or_hash, options = {})
141:       ActiveSupport::Deprecation.warn("formatted_polymorphic_path has been deprecated. Please pass :format to the polymorphic_path method instead", caller)
142:       options[:format] = record_or_hash.pop if record_or_hash === Array
143:       polymorphic_url(record_or_hash, options.merge(:routing_type => :path))
144:     end
formatted_polymorphic_url(record_or_hash, options = {})

[ show source ]

     # File actionpack/lib/action_controller/polymorphic_routes.rb, line 134
134:     def formatted_polymorphic_url(record_or_hash, options = {})
135:       ActiveSupport::Deprecation.warn("formatted_polymorphic_url has been deprecated. Please pass :format to the polymorphic_url method instead", caller)
136:       options[:format] = record_or_hash.pop if Array === record_or_hash
137:       polymorphic_url(record_or_hash, options)
138:     end
polymorphic_path(record_or_hash_or_array, options = {})

Returns the path component of a URL for the given record. It uses polymorphic_url with :routing_type => :path.

[ show source ]

     # File actionpack/lib/action_controller/polymorphic_routes.rb, line 112
112:     def polymorphic_path(record_or_hash_or_array, options = {})
113:       options[:routing_type] = :path
114:       polymorphic_url(record_or_hash_or_array, options)
115:     end
polymorphic_url(record_or_hash_or_array, options = {})

Constructs a call to a named RESTful route for the given record and returns the resulting URL string. For example: 

  # calls post_url(post)
  polymorphic_url(post) # => "http://example.com/posts/1"
  polymorphic_url([blog, post]) # => "http://example.com/blogs/1/posts/1"
  polymorphic_url([:admin, blog, post]) # => "http://example.com/admin/blogs/1/posts/1"
  polymorphic_url([user, :blog, post]) # => "http://example.com/users/1/blog/posts/1"

Options

  • :action - Specifies the action prefix for the named route: :new or :edit. Default is no prefix.
  • :routing_type - Allowed values are :path or :url. Default is :url.

Examples

  # an Article record
  polymorphic_url(record)  # same as article_url(record)

  # a Comment record
  polymorphic_url(record)  # same as comment_url(record)

  # it recognizes new records and maps to the collection
  record = Comment.new
  polymorphic_url(record)  # same as comments_url()

[ show source ]

     # File actionpack/lib/action_controller/polymorphic_routes.rb, line 73
 73:     def polymorphic_url(record_or_hash_or_array, options = {})
 74:       if record_or_hash_or_array.kind_of?(Array)
 75:         record_or_hash_or_array = record_or_hash_or_array.compact
 76:         record_or_hash_or_array = record_or_hash_or_array[0] if record_or_hash_or_array.size == 1
 77:       end
 78: 
 79:       record = extract_record(record_or_hash_or_array)
 80: 
 81:       args = case record_or_hash_or_array
 82:         when Hash;  [ record_or_hash_or_array ]
 83:         when Array; record_or_hash_or_array.dup
 84:         else        [ record_or_hash_or_array ]
 85:       end
 86: 
 87:       inflection =
 88:         case
 89:         when options[:action].to_s == "new"
 90:           args.pop
 91:           :singular
 92:         when record.respond_to?(:new_record?) && record.new_record?
 93:           args.pop
 94:           :plural
 95:         else
 96:           :singular
 97:         end
 98: 
 99:       args.delete_if {|arg| arg.is_a?(Symbol) || arg.is_a?(String)}
100:       named_route = build_named_route_call(record_or_hash_or_array, inflection, options)
101: 
102:       url_options = options.except(:action, :routing_type)
103:       unless url_options.empty?
104:         args.last.kind_of?(Hash) ? args.last.merge!(url_options) : args << url_options
105:       end
106: 
107:       __send__(named_route, *args)
108:     end