Module: ActionDispatch::Routing::Mapper::Scoping

Relationships & Source Files
Extension / Inclusion / Inheritance Descendants
Included In: `::ActionDispatch::Routing::Mapper`
Defined in:	actionpack/lib/action_dispatch/routing/mapper.rb

Overview

You may wish to organize groups of controllers under a namespace. Most commonly, you might group a number of administrative controllers under an admin namespace. You would place these controllers under the app/controllers/admin directory, and you can group them together in your router:

namespace "admin" do
  resources :posts, :comments
end

This will create a number of routes for each of the posts and comments controller. For Admin::PostsController, ::Rails will create:

GET       /admin/posts
GET       /admin/posts/new
POST      /admin/posts
GET       /admin/posts/1
GET       /admin/posts/1/edit
PATCH/PUT /admin/posts/1
DELETE    /admin/posts/1

If you want to route /posts (without the prefix /admin) to Admin::PostsController, you could use

scope module: "admin" do
  resources :posts
end

or, for a single case

resources :posts, module: "admin"

If you want to route /admin/posts to PostsController (without the Admin:: module prefix), you could use

scope "/admin" do
  resources :posts
end

or, for a single case

resources :posts, path: "/admin/posts"

In each of these cases, the named routes remain the same as if you did not use scope. In the last case, the following paths map to PostsController:

GET       /admin/posts
GET       /admin/posts/new
POST      /admin/posts
GET       /admin/posts/1
GET       /admin/posts/1/edit
PATCH/PUT /admin/posts/1
DELETE    /admin/posts/1

Instance Method Summary

#constraints(constraints = {})

Parameter Restriction Allows you to constrain the nested routes based on a set of rules.
#controller(controller)

Scopes routes to a specific controller.
#defaults(defaults = {})

Allows you to set default parameters for a route, such as this:
#namespace(path, options = {})

Scopes routes to a specific namespace.
#scope(*args)

Scopes a set of routes to the given default options.

Instance Method Details

#constraints(constraints = {})

Parameter Restriction

Allows you to constrain the nested routes based on a set of rules. For instance, in order to change the routes to allow for a dot character in the id parameter:

constraints(id: /\d\.\d/) do
  resources :posts
end

Now routes such as /posts/1 will no longer be valid, but /posts/1.1 will be. The id parameter must match the constraint passed in for this example.

You may use this to also restrict other parameters:

resources :posts do
  constraints(post_id: /\d\.\d/) do
    resources :comments
  end
end

Restricting based on IP

Routes can also be constrained to an IP or a certain range of IP addresses:

constraints(ip: /192\.168\.\d\.\d/) do
  resources :posts
end

Any user connecting from the 192.168.* range will be able to see this resource, where as any user connecting outside of this range will be told there is no such route.

Dynamic request matching

Requests to routes can be constrained based on specific criteria:

constraints(-> (req) { /iPhone/.match?(req.env["HTTP_USER_AGENT"]) }) do
  resources :iphones
end

You are able to move this logic out into a class if it is too complex for routes. This class must have a matches? method defined on it which either returns true if the user should be given access to that route, or false if the user should not.

class Iphone
  def self.matches?(request)
    /iPhone/.match?(request.env["HTTP_USER_AGENT"])
  end
end

An expected place for this code would be lib/constraints.

This class is then used like this:

constraints(Iphone) do
  resources :iphones
end

[ GitHub ]

# File 'actionpack/lib/action_dispatch/routing/mapper.rb', line 1029


def constraints(constraints = {})
  scope(constraints: constraints) { yield }
end

#controller(controller)

Scopes routes to a specific controller

controller "food" do
  match "bacon", action: :bacon, via: :get
end

[ GitHub ]

# File 'actionpack/lib/action_dispatch/routing/mapper.rb', line 914


def controller(controller)
  @scope = @scope.new(controller: controller)
  yield
ensure
  @scope = @scope.parent
end

#defaults(defaults = {})

Allows you to set default parameters for a route, such as this:

defaults id: 'home' do
  match 'scoped_pages/(:id)', to: 'pages#show'
end

Using this, the :id parameter here will default to ‘home’.

[ GitHub ]

# File 'actionpack/lib/action_dispatch/routing/mapper.rb', line 1038


def defaults(defaults = {})
  @scope = @scope.new(defaults: merge_defaults_scope(@scope[:defaults], defaults))
  yield
ensure
  @scope = @scope.parent
end

#namespace(path, options = {})

Scopes routes to a specific namespace. For example:

namespace :admin do
  resources :posts
end

This generates the following routes:

    admin_posts GET       /admin/posts(.:format)          admin/posts#index
    admin_posts POST      /admin/posts(.:format)          admin/posts#create
 new_admin_post GET       /admin/posts/new(.:format)      admin/posts#new
edit_admin_post GET       /admin/posts/:id/edit(.:format) admin/posts#edit
     admin_post GET       /admin/posts/:id(.:format)      admin/posts#show
     admin_post PATCH/PUT /admin/posts/:id(.:format)      admin/posts#update
     admin_post DELETE    /admin/posts/:id(.:format)      admin/posts#destroy

Options

The :path, :as, :module, :shallow_path and :shallow_prefix options all default to the name of the namespace.

For options, see Base#match. For :shallow_path option, see Resources#resources.

# accessible through /sekret/posts rather than /admin/posts
namespace :admin, path: "sekret" do
  resources :posts
end

# maps to {Sekret::PostsController} rather than {Admin::PostsController}
namespace :admin, module: "sekret" do
  resources :posts
end

# generates {sekret_posts_path} rather than {admin_posts_path}
namespace :admin, as: "sekret" do
  resources :posts
end

[ GitHub ]

# File 'actionpack/lib/action_dispatch/routing/mapper.rb', line 959


def namespace(path, options = {})
  path = path.to_s

  defaults = {
    module:         path,
    as:             options.fetch(:as, path),
    shallow_path:   options.fetch(:path, path),
    shallow_prefix: options.fetch(:as, path)
  }

  path_scope(options.delete(:path) { path }) do
    scope(defaults.merge!(options)) { yield }
  end
end

#scope(*args)

Scopes a set of routes to the given default options.

Take the following route definition as an example:

scope path: ":account_id", as: "account" do
  resources :projects
end

This generates helpers such as account_projects_path, just like resources does. The difference here being that the routes generated are like /:account_id/projects, rather than /accounts/:account_id/projects.

Options

Takes same options as Base#match and Resources#resources.

# route /posts (without the prefix /admin) to {Admin::PostsController}
scope module: "admin" do
  resources :posts
end

# prefix the posts resource's requests with '/admin'
scope path: "/admin" do
  resources :posts
end

# prefix the routing helper name: {sekret_posts_path} instead of {posts_path}
scope as: "sekret" do
  resources :posts
end

[ GitHub ]

# File 'actionpack/lib/action_dispatch/routing/mapper.rb', line 855


def scope(*args)
  options = args.extract_options!.dup
  scope = {}

  options[:path] = args.flatten.join("/") if args.any?
  options[:constraints] ||= {}

  unless nested_scope?
    options[:shallow_path] ||= options[:path] if options.key?(:path)
    options[:shallow_prefix] ||= options[:as] if options.key?(:as)
  end

  if options[:constraints].is_a?(Hash)
    defaults = options[:constraints].select do |k, v|
      URL_OPTIONS.include?(k) && (v.is_a?(String) || v.is_a?(Integer))
    end

    options[:defaults] = defaults.merge(options[:defaults] || {})
  else
    block, options[:constraints] = options[:constraints], {}
  end

  if options.key?(:only) || options.key?(:except)
    scope[:action_options] = { only: options.delete(:only),
                               except: options.delete(:except) }
  end

  if options.key? :anchor
    raise ArgumentError, "anchor is ignored unless passed to `match`"
  end

  @scope.options.each do |option|
    if option == :blocks
      value = block
    elsif option == :options
      value = options
    else
      value = options.delete(option) { POISON }
    end

    unless POISON == value
      scope[option] = send("merge_#{option}_scope", @scope[option], value)
    end
  end

  @scope = @scope.new scope
  yield
  self
ensure
  @scope = @scope.parent
end