ActionDispatch::Routing::PolymorphicRoutes

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"

Public Instance Methods

polymorphic_path(record_or_hash_or_array, options = {}) click to toggle source

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

     # File lib/action_dispatch/routing/polymorphic_routes.rb, line 119
119:       def polymorphic_path(record_or_hash_or_array, options = {})
120:         polymorphic_url(record_or_hash_or_array, options.merge(:routing_type => :path))
121:       end

polymorphic_url(record_or_hash_or_array, options = {}) click to toggle source

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"
  polymorphic_url(Comment) # => "http://example.com/comments"

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()

  # the class of a record will also map to the collection
  polymorphic_url(Comment) # same as comments_url()

     # File lib/action_dispatch/routing/polymorphic_routes.rb, line 78
 78:       def polymorphic_url(record_or_hash_or_array, options = {})
 79:         if record_or_hash_or_array.kind_of?(Array)
 80:           record_or_hash_or_array = record_or_hash_or_array.compact
 81:           record_or_hash_or_array = record_or_hash_or_array[0] if record_or_hash_or_array.size == 1
 82:         end
 83: 
 84:         record = extract_record(record_or_hash_or_array)
 85:         record = record.to_model if record.respond_to?(:to_model)
 86: 
 87:         args = case record_or_hash_or_array
 88:           when Hash;  [ record_or_hash_or_array ]
 89:           when Array; record_or_hash_or_array.dup
 90:           else        [ record_or_hash_or_array ]
 91:         end
 92: 
 93:         inflection = if options[:action].to_s == "new"
 94:           args.pop
 95:           :singular
 96:         elsif (record.respond_to?(:persisted?) && !record.persisted?)
 97:           args.pop
 98:           :plural
 99:         elsif record.is_a?(Class)
100:           args.pop
101:           :plural
102:         else
103:           :singular
104:         end
105: 
106:         args.delete_if {|arg| arg.is_a?(Symbol) || arg.is_a?(String)}
107:         named_route = build_named_route_call(record_or_hash_or_array, inflection, options)
108: 
109:         url_options = options.except(:action, :routing_type)
110:         unless url_options.empty?
111:           args.last.kind_of?(Hash) ? args.last.merge!(url_options) : args << url_options
112:         end
113: 
114:         send(named_route, *args)
115:       end

Private Instance Methods

action_prefix(options) click to toggle source

     # File lib/action_dispatch/routing/polymorphic_routes.rb, line 140
140:         def action_prefix(options)
141:           options[:action] ? "#{options[:action]}_" : ''
142:         end

build_named_route_call(records, inflection, options = {}) click to toggle source

     # File lib/action_dispatch/routing/polymorphic_routes.rb, line 148
148:         def build_named_route_call(records, inflection, options = {})
149:           unless records.is_a?(Array)
150:             record = extract_record(records)
151:             route  = []
152:           else
153:             record = records.pop
154:             route = records.map do |parent|
155:               if parent.is_a?(Symbol) || parent.is_a?(String)
156:                 parent
157:               else
158:                 ActiveModel::Naming.plural(parent).singularize
159:               end
160:             end
161:           end
162: 
163:           if record.is_a?(Symbol) || record.is_a?(String)
164:             route << record
165:           else
166:             route << ActiveModel::Naming.plural(record)
167:             route = [route.join("_").singularize] if inflection == :singular
168:             route << "index" if ActiveModel::Naming.uncountable?(record) && inflection == :plural
169:           end
170: 
171:           route << routing_type(options)
172: 
173:           action_prefix(options) + route.join("_")
174:         end

extract_record(record_or_hash_or_array) click to toggle source

     # File lib/action_dispatch/routing/polymorphic_routes.rb, line 176
176:         def extract_record(record_or_hash_or_array)
177:           case record_or_hash_or_array
178:             when Array; record_or_hash_or_array.last
179:             when Hash;  record_or_hash_or_array[:id]
180:             else        record_or_hash_or_array
181:           end
182:         end

routing_type(options) click to toggle source

     # File lib/action_dispatch/routing/polymorphic_routes.rb, line 144
144:         def routing_type(options)
145:           options[:routing_type] || :url
146:         end

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