module ActionDispatch::Routing::PolymorphicRoutes - actionpack-4.2.4 Documentation

# module 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"

## Usage with mounted engines¶ ↑

If you are using a mounted engine and you need to use a #polymorphic_url pointing at the engine's routes, pass in the engine's route proxy as the first argument to the method. For example:

    polymorphic_url([blog, @post])  # calls blog.post_path(@post)
    form_for([blog, @post])         # => "/blog/posts/1"

### 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 123
    def polymorphic_path(record_or_hash_or_array, options = {})
      if Hash === record_or_hash_or_array
        options = record_or_hash_or_array.merge(options)
        record  = options.delete :id
        return polymorphic_path record, options
      end

      opts   = options.dup
      action = opts.delete :action
      type   = :path

      HelperMethodBuilder.polymorphic_method self,
                                             record_or_hash_or_array,
                                             action,
                                             type,
                                             opts
    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`.

Also includes all the options from `url_for`. These include such things as `:anchor` or `:trailing_slash`. Example usage is given below:

    polymorphic_url([blog, post], anchor: 'my_anchor')
      # => "http://example.com/blogs/1/posts/1#my_anchor"
    polymorphic_url([blog, post], anchor: 'my_anchor', script_name: "/my_app")
      # => "http://example.com/my_app/blogs/1/posts/1#my_anchor"

For all of these options, see the documentation for `url_for`.

#### Functionality¶ ↑

    # 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 103
    def polymorphic_url(record_or_hash_or_array, options = {})
      if Hash === record_or_hash_or_array
        options = record_or_hash_or_array.merge(options)
        record  = options.delete :id
        return polymorphic_url record, options
      end

      opts   = options.dup
      action = opts.delete :action
      type   = opts.delete(:routing_type) || :url

      HelperMethodBuilder.polymorphic_method self,
                                             record_or_hash_or_array,
                                             action,
                                             type,
                                             opts
    end

### Private Instance Methods

polymorphic_path_for_action(action, record_or_hash, options) click to toggle source

    # File lib/action_dispatch/routing/polymorphic_routes.rb, line 160
    def polymorphic_path_for_action(action, record_or_hash, options)
      polymorphic_path(record_or_hash, options.merge(:action => action))
    end

polymorphic_url_for_action(action, record_or_hash, options) click to toggle source

    # File lib/action_dispatch/routing/polymorphic_routes.rb, line 156
    def polymorphic_url_for_action(action, record_or_hash, options)
      polymorphic_url(record_or_hash, options.merge(:action => action))
    end