Module: ActionDispatch::Routing::PolymorphicRoutes

Included in:
UrlFor
Defined in:
lib/action_dispatch/routing/polymorphic_routes.rb

Overview

# Action Dispatch 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 the 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"

Defined Under Namespace

Classes: HelperMethodBuilder

Instance Method Summary collapse

Instance Method Details

#polymorphic_path(record_or_hash_or_array, options = {}) ⇒ Object

Returns the path component of a URL for the given record.



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# File 'lib/action_dispatch/routing/polymorphic_routes.rb', line 133

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

  if mapping = polymorphic_mapping(record_or_hash_or_array)
    return mapping.call(self, [record_or_hash_or_array, options], true)
  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 = {}) ⇒ Object

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](ActionDispatch::Routing::UrlFor).

#### 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()



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# File 'lib/action_dispatch/routing/polymorphic_routes.rb', line 110

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

  if mapping = polymorphic_mapping(record_or_hash_or_array)
    return mapping.call(self, [record_or_hash_or_array, options], false)
  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