ActionController::PolymorphicRoutes

• actionpack/lib/action_controller/polymorphic_routes.rb

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"

• formatted_polymorphic_path
• formatted_polymorphic_url
• polymorphic_path
• polymorphic_url

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

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()