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Rails Routing from the Outside In
This guide covers the user-facing features of Rails routing.
After reading this guide, you will know:
- How to interpret the code in
config/routes.rb
. - How to construct your own routes, using either the preferred resourceful style or the
match
method. - How to declare route parameters, which are passed onto controller actions.
- How to automatically create paths and URLs using route helpers.
- Advanced techniques such as creating constraints and mounting Rack endpoints.
The Purpose of the Rails Router
The Rails router recognizes URLs and dispatches them to a controller's action, or to a Rack application. It can also generate paths and URLs, avoiding the need to hardcode strings in your views.
Connecting URLs to Code
When your Rails application receives an incoming request for:
GET /patients/17
it asks the router to match it to a controller action. If the first matching route is:
get '/patients/:id', to: 'patients#show'
the request is dispatched to the patients
controller's show
action with { id: '17' }
in params
.
NOTE: Rails uses snake_case for controller names here, if you have a multiple word controller like MonsterTrucksController
, you want to use monster_trucks#show
for example.
Generating Paths and URLs from Code
You can also generate paths and URLs. If the route above is modified to be:
get '/patients/:id', to: 'patients#show', as: 'patient'
and your application contains this code in the controller:
@patient = Patient.find(params[:id])
and this in the corresponding view:
<%= link_to 'Patient Record', patient_path(@patient) %>
then the router will generate the path /patients/17
. This reduces the brittleness of your view and makes your code easier to understand. Note that the id does not need to be specified in the route helper.
Configuring the Rails Router
The routes for your application or engine live in the file config/routes.rb
and typically looks like this:
Rails.application.routes.draw do
resources :brands, only: [:index, :show] do
resources :products, only: [:index, :show]
end
resource :basket, only: [:show, :update, :destroy]
resolve("Basket") { route_for(:basket) }
end
Since this is a regular Ruby source file you can use all of its features to help you define your routes but be careful with variable names as they can clash with the DSL methods of the router.
NOTE: The Rails.application.routes.draw do ... end
block that wraps your route definitions is required to establish the scope for the router DSL and must not be deleted.
Resource Routing: the Rails Default
Resource routing allows you to quickly declare all of the common routes for a given resourceful controller. A single call to resources
can declare all of the necessary routes for your index
, show
, new
, edit
, create
, update
and destroy
actions.
Resources on the Web
Browsers request pages from Rails by making a request for a URL using a specific HTTP method, such as GET
, POST
, PATCH
, PUT
and DELETE
. Each method is a request to perform an operation on the resource. A resource route maps a number of related requests to actions in a single controller.
When your Rails application receives an incoming request for:
DELETE /photos/17
it asks the router to map it to a controller action. If the first matching route is:
resources :photos
Rails would dispatch that request to the destroy
action on the photos
controller with { id: '17' }
in params
.
CRUD, Verbs, and Actions
In Rails, a resourceful route provides a mapping between HTTP verbs and URLs to controller actions. By convention, each action also maps to a specific CRUD operation in a database. A single entry in the routing file, such as:
resources :photos
creates seven different routes in your application, all mapping to the Photos
controller:
HTTP Verb | Path | Controller#Action | Used for |
---|---|---|---|
GET | /photos | photos#index | display a list of all photos |
GET | /photos/new | photos#new | return an HTML form for creating a new photo |
POST | /photos | photos#create | create a new photo |
GET | /photos/:id | photos#show | display a specific photo |
GET | /photos/:id/edit | photos#edit | return an HTML form for editing a photo |
PATCH/PUT | /photos/:id | photos#update | update a specific photo |
DELETE | /photos/:id | photos#destroy | delete a specific photo |
NOTE: Because the router uses the HTTP verb and URL to match inbound requests, four URLs map to seven different actions.
NOTE: Rails routes are matched in the order they are specified, so if you have a resources :photos
above a get 'photos/poll'
the show
action's route for the resources
line will be matched before the get
line. To fix this, move the get
line above the resources
line so that it is matched first.
Path and URL Helpers
Creating a resourceful route will also expose a number of helpers to the controllers in your application. In the case of resources :photos
:
photos_path
returns/photos
new_photo_path
returns/photos/new
edit_photo_path(:id)
returns/photos/:id/edit
(for instance,edit_photo_path(10)
returns/photos/10/edit
)photo_path(:id)
returns/photos/:id
(for instance,photo_path(10)
returns/photos/10
)
Each of these helpers has a corresponding _url
helper (such as photos_url
) which returns the same path prefixed with the current host, port, and path prefix.
Defining Multiple Resources at the Same Time
If you need to create routes for more than one resource, you can save a bit of typing by defining them all with a single call to resources
:
resources :photos, :books, :videos
This works exactly the same as:
resources :photos
resources :books
resources :videos
Singular Resources
Sometimes, you have a resource that clients always look up without referencing an ID. For example, you would like /profile
to always show the profile of the currently logged in user. In this case, you can use a singular resource to map /profile
(rather than /profile/:id
) to the show
action:
get 'profile', to: 'users#show'
Passing a String
to to:
will expect a controller#action
format. When using a Symbol
, the to:
option should be replaced with action:
. When using a String
without a #
, the to:
option should be replaced with controller:
:
get 'profile', action: :show, controller: 'users'
This resourceful route:
resource :geocoder
resolve('Geocoder') { [:geocoder] }
creates six different routes in your application, all mapping to the Geocoders
controller:
HTTP Verb | Path | Controller#Action | Used for |
---|---|---|---|
GET | /geocoder/new | geocoders#new | return an HTML form for creating the geocoder |
POST | /geocoder | geocoders#create | create the new geocoder |
GET | /geocoder | geocoders#show | display the one and only geocoder resource |
GET | /geocoder/edit | geocoders#edit | return an HTML form for editing the geocoder |
PATCH/PUT | /geocoder | geocoders#update | update the one and only geocoder resource |
DELETE | /geocoder | geocoders#destroy | delete the geocoder resource |
NOTE: Because you might want to use the same controller for a singular route (/account
) and a plural route (/accounts/45
), singular resources map to plural controllers. So that, for example, resource :photo
and resources :photos
creates both singular and plural routes that map to the same controller (PhotosController
).
A singular resourceful route generates these helpers:
new_geocoder_path
returns/geocoder/new
edit_geocoder_path
returns/geocoder/edit
geocoder_path
returns/geocoder
As with plural resources, the same helpers ending in _url
will also include the host, port, and path prefix.
Controller Namespaces and Routing
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, and place these controllers under the app/controllers/admin
directory. You can route to such a group by using a namespace
block:
namespace :admin do
resources :articles, :comments
end
This will create a number of routes for each of the articles
and comments
controller. For Admin::ArticlesController
, Rails will create:
HTTP Verb | Path | Controller#Action | Named Route Helper |
---|---|---|---|
GET | /admin/articles | admin/articles#index | admin_articles_path |
GET | /admin/articles/new | admin/articles#new | new_admin_article_path |
POST | /admin/articles | admin/articles#create | admin_articles_path |
GET | /admin/articles/:id | admin/articles#show | admin_article_path(:id) |
GET | /admin/articles/:id/edit | admin/articles#edit | edit_admin_article_path(:id) |
PATCH/PUT | /admin/articles/:id | admin/articles#update | admin_article_path(:id) |
DELETE | /admin/articles/:id | admin/articles#destroy | admin_article_path(:id) |
If instead you want to route /articles
(without the prefix /admin
) to Admin::ArticlesController
, you can specify the module with a scope
block:
scope module: 'admin' do
resources :articles, :comments
end
This can also be done for a single route:
resources :articles, module: 'admin'
If instead you want to route /admin/articles
to ArticlesController
(without the Admin::
module prefix), you can specify the path with a scope
block:
scope '/admin' do
resources :articles, :comments
end
This can also be done for a single route:
resources :articles, path: '/admin/articles'
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 ArticlesController
:
HTTP Verb | Path | Controller#Action | Named Route Helper |
---|---|---|---|
GET | /admin/articles | articles#index | articles_path |
GET | /admin/articles/new | articles#new | new_article_path |
POST | /admin/articles | articles#create | articles_path |
GET | /admin/articles/:id | articles#show | article_path(:id) |
GET | /admin/articles/:id/edit | articles#edit | edit_article_path(:id) |
PATCH/PUT | /admin/articles/:id | articles#update | article_path(:id) |
DELETE | /admin/articles/:id | articles#destroy | article_path(:id) |
TIP: If you need to use a different controller namespace inside a namespace
block you can specify an absolute controller path, e.g: get '/foo', to: '/foo#index'
.
Nested Resources
It's common to have resources that are logically children of other resources. For example, suppose your application includes these models:
class Magazine < ApplicationRecord
has_many :ads
end
class Ad < ApplicationRecord
belongs_to :magazine
end
Nested routes allow you to capture this relationship in your routing. In this case, you could include this route declaration:
resources :magazines do
resources :ads
end
In addition to the routes for magazines, this declaration will also route ads to an AdsController
. The ad URLs require a magazine:
HTTP Verb | Path | Controller#Action | Used for |
---|---|---|---|
GET | /magazines/:magazine_id/ads | ads#index | display a list of all ads for a specific magazine |
GET | /magazines/:magazine_id/ads/new | ads#new | return an HTML form for creating a new ad belonging to a specific magazine |
POST | /magazines/:magazine_id/ads | ads#create | create a new ad belonging to a specific magazine |
GET | /magazines/:magazine_id/ads/:id | ads#show | display a specific ad belonging to a specific magazine |
GET | /magazines/:magazine_id/ads/:id/edit | ads#edit | return an HTML form for editing an ad belonging to a specific magazine |
PATCH/PUT | /magazines/:magazine_id/ads/:id | ads#update | update a specific ad belonging to a specific magazine |
DELETE | /magazines/:magazine_id/ads/:id | ads#destroy | delete a specific ad belonging to a specific magazine |
This will also create routing helpers such as magazine_ads_url
and edit_magazine_ad_path
. These helpers take an instance of Magazine as the first parameter (magazine_ads_url(@magazine)
).
Limits to Nesting
You can nest resources within other nested resources if you like. For example:
resources :publishers do
resources :magazines do
resources :photos
end
end
Deeply-nested resources quickly become cumbersome. In this case, for example, the application would recognize paths such as:
/publishers/1/magazines/2/photos/3
The corresponding route helper would be publisher_magazine_photo_url
, requiring you to specify objects at all three levels. Indeed, this situation is confusing enough that a popular article by Jamis Buck proposes a rule of thumb for good Rails design:
TIP: Resources should never be nested more than 1 level deep.
Shallow Nesting
One way to avoid deep nesting (as recommended above) is to generate the collection actions scoped under the parent, so as to get a sense of the hierarchy, but to not nest the member actions. In other words, to only build routes with the minimal amount of information to uniquely identify the resource, like this:
resources :articles do
resources :comments, only: [:index, :new, :create]
end
resources :comments, only: [:show, :edit, :update, :destroy]
This idea strikes a balance between descriptive routes and deep nesting. There exists shorthand syntax to achieve just that, via the :shallow
option:
resources :articles do
resources :comments, shallow: true
end
This will generate the exact same routes as the first example. You can also specify the :shallow
option in the parent resource, in which case all of the nested resources will be shallow:
resources :articles, shallow: true do
resources :comments
resources :quotes
resources :drafts
end
The shallow
method of the DSL creates a scope inside of which every nesting is shallow. This generates the same routes as the previous example:
shallow do
resources :articles do
resources :comments
resources :quotes
resources :drafts
end
end
There exist two options for scope
to customize shallow routes. :shallow_path
prefixes member paths with the specified parameter:
scope shallow_path: "sekret" do
resources :articles do
resources :comments, shallow: true
end
end
The comments resource here will have the following routes generated for it:
HTTP Verb | Path | Controller#Action | Named Route Helper |
---|---|---|---|
GET | /articles/:article_id/comments(.:format) | comments#index | article_comments_path |
POST | /articles/:article_id/comments(.:format) | comments#create | article_comments_path |
GET | /articles/:article_id/comments/new(.:format) | comments#new | new_article_comment_path |
GET | /sekret/comments/:id/edit(.:format) | comments#edit | edit_comment_path |
GET | /sekret/comments/:id(.:format) | comments#show | comment_path |
PATCH/PUT | /sekret/comments/:id(.:format) | comments#update | comment_path |
DELETE | /sekret/comments/:id(.:format) | comments#destroy | comment_path |
The :shallow_prefix
option adds the specified parameter to the named route helpers:
scope shallow_prefix: "sekret" do
resources :articles do
resources :comments, shallow: true
end
end
The comments resource here will have the following routes generated for it:
HTTP Verb | Path | Controller#Action | Named Route Helper |
---|---|---|---|
GET | /articles/:article_id/comments(.:format) | comments#index | article_comments_path |
POST | /articles/:article_id/comments(.:format) | comments#create | article_comments_path |
GET | /articles/:article_id/comments/new(.:format) | comments#new | new_article_comment_path |
GET | /comments/:id/edit(.:format) | comments#edit | edit_sekret_comment_path |
GET | /comments/:id(.:format) | comments#show | sekret_comment_path |
PATCH/PUT | /comments/:id(.:format) | comments#update | sekret_comment_path |
DELETE | /comments/:id(.:format) | comments#destroy | sekret_comment_path |
Routing Concerns
Routing concerns allow you to declare common routes that can be reused inside other resources and routes. To define a concern, use a concern
block:
concern :commentable do
resources :comments
end
concern :image_attachable do
resources :images, only: :index
end
These concerns can be used in resources to avoid code duplication and share behavior across routes:
resources :messages, concerns: :commentable
resources :articles, concerns: [:commentable, :image_attachable]
The above is equivalent to:
resources :messages do
resources :comments
end
resources :articles do
resources :comments
resources :images, only: :index
end
You can also use them anywhere by calling concerns
. For example, in a scope
or namespace
block:
namespace :articles do
concerns :commentable
end
Creating Paths and URLs from Objects
In addition to using the routing helpers, Rails can also create paths and URLs from an array of parameters. For example, suppose you have this set of routes:
resources :magazines do
resources :ads
end
When using magazine_ad_path
, you can pass in instances of Magazine
and Ad
instead of the numeric IDs:
<%= link_to 'Ad details', magazine_ad_path(@magazine, @ad) %>
You can also use url_for
with a set of objects, and Rails will automatically determine which route you want:
<%= link_to 'Ad details', url_for([@magazine, @ad]) %>
In this case, Rails will see that @magazine
is a Magazine
and @ad
is an Ad
and will therefore use the magazine_ad_path
helper. In helpers like link_to
, you can specify just the object in place of the full url_for
call:
<%= link_to 'Ad details', [@magazine, @ad] %>
If you wanted to link to just a magazine:
<%= link_to 'Magazine details', @magazine %>
For other actions, you just need to insert the action name as the first element of the array:
<%= link_to 'Edit Ad', [:edit, @magazine, @ad] %>
This allows you to treat instances of your models as URLs, and is a key advantage to using the resourceful style.
Adding More RESTful Actions
You are not limited to the seven routes that RESTful routing creates by default. If you like, you may add additional routes that apply to the collection or individual members of the collection.
Adding Member Routes
To add a member route, just add a member
block into the resource block:
resources :photos do
member do
get 'preview'
end
end
This will recognize /photos/1/preview
with GET, and route to the preview
action of PhotosController
, with the resource id value passed in params[:id]
. It will also create the preview_photo_url
and preview_photo_path
helpers.
Within the block of member routes, each route name specifies the HTTP verb that
will be recognized. You can use get
, patch
, put
, post
, or delete
here
. If you don't have multiple member
routes, you can also pass :on
to a
route, eliminating the block:
resources :photos do
get 'preview', on: :member
end
You can leave out the :on
option, this will create the same member route except that the resource id value will be available in params[:photo_id]
instead of params[:id]
. Route helpers will also be renamed from preview_photo_url
and preview_photo_path
to photo_preview_url
and photo_preview_path
.
Adding Collection Routes
To add a route to the collection, use a collection
block:
resources :photos do
collection do
get 'search'
end
end
This will enable Rails to recognize paths such as /photos/search
with GET, and route to the search
action of PhotosController
. It will also create the search_photos_url
and search_photos_path
route helpers.
Just as with member routes, you can pass :on
to a route:
resources :photos do
get 'search', on: :collection
end
NOTE: If you're defining additional resource routes with a symbol as the first positional argument, be mindful that it is not equivalent to using a string. Symbols infer controller actions while strings infer paths.
Adding Routes for Additional New Actions
To add an alternate new action using the :on
shortcut:
resources :comments do
get 'preview', on: :new
end
This will enable Rails to recognize paths such as /comments/new/preview
with GET, and route to the preview
action of CommentsController
. It will also create the preview_new_comment_url
and preview_new_comment_path
route helpers.
TIP: If you find yourself adding many extra actions to a resourceful route, it's time to stop and ask yourself whether you're disguising the presence of another resource.
Non-Resourceful Routes
In addition to resource routing, Rails has powerful support for routing arbitrary URLs to actions. Here, you don't get groups of routes automatically generated by resourceful routing. Instead, you set up each route separately within your application.
While you should usually use resourceful routing, there are still many places where the simpler routing is more appropriate. There's no need to try to shoehorn every last piece of your application into a resourceful framework if that's not a good fit.
In particular, simple routing makes it very easy to map legacy URLs to new Rails actions.
Bound Parameters
When you set up a regular route, you supply a series of symbols that Rails maps to parts of an incoming HTTP request. For example, consider this route:
get 'photos(/:id)', to: 'photos#display'
If an incoming request of /photos/1
is processed by this route (because it hasn't matched any previous route in the file), then the result will be to invoke the display
action of the PhotosController
, and to make the final parameter "1"
available as params[:id]
. This route will also route the incoming request of /photos
to PhotosController#display
, since :id
is an optional parameter, denoted by parentheses.
Dynamic Segments
You can set up as many dynamic segments within a regular route as you like. Any segment will be available to the action as part of params
. If you set up this route:
get 'photos/:id/:user_id', to: 'photos#show'
An incoming path of /photos/1/2
will be dispatched to the show
action of the PhotosController
. params[:id]
will be "1"
, and params[:user_id]
will be "2"
.
TIP: By default, dynamic segments don't accept dots - this is because the dot is used as a separator for formatted routes. If you need to use a dot within a dynamic segment, add a constraint that overrides this – for example, id: /[^\/]+/
allows anything except a slash.
Static Segments
You can specify static segments when creating a route by not prepending a colon to a segment:
get 'photos/:id/with_user/:user_id', to: 'photos#show'
This route would respond to paths such as /photos/1/with_user/2
. In this case, params
would be { controller: 'photos', action: 'show', id: '1', user_id: '2' }
.
The Query String
The params
will also include any parameters from the query string. For example, with this route:
get 'photos/:id', to: 'photos#show'
An incoming path of /photos/1?user_id=2
will be dispatched to the show
action of the Photos
controller. params
will be { controller: 'photos', action: 'show', id: '1', user_id: '2' }
.
Defining Defaults
You can define defaults in a route by supplying a hash for the :defaults
option. This even applies to parameters that you do not specify as dynamic segments. For example:
get 'photos/:id', to: 'photos#show', defaults: { format: 'jpg' }
Rails would match photos/12
to the show
action of PhotosController
, and set params[:format]
to "jpg"
.
You can also use a defaults
block to define the defaults for multiple items:
defaults format: :json do
resources :photos
end
NOTE: You cannot override defaults via query parameters - this is for security reasons. The only defaults that can be overridden are dynamic segments via substitution in the URL path.
Naming Routes
You can specify a name for any route using the :as
option:
get 'exit', to: 'sessions#destroy', as: :logout
This will create logout_path
and logout_url
as named route helpers in your application. Calling logout_path
will return /exit
You can also use this to override routing methods defined by resources by placing custom routes before the resource is defined, like this:
get ':username', to: 'users#show', as: :user
resources :users
This will define a user_path
method that will be available in controllers, helpers, and views that will go to a route such as /bob
. Inside the show
action of UsersController
, params[:username]
will contain the username for the user. Change :username
in the route definition if you do not want your parameter name to be :username
.
HTTP Verb Constraints
In general, you should use the get
, post
, put
, patch
, and delete
methods to constrain a route to a particular verb. You can use the match
method with the :via
option to match multiple verbs at once:
match 'photos', to: 'photos#show', via: [:get, :post]
You can match all verbs to a particular route using via: :all
:
match 'photos', to: 'photos#show', via: :all
NOTE: Routing both GET
and POST
requests to a single action has security implications. In general, you should avoid routing all verbs to an action unless you have a good reason to.
NOTE: GET
in Rails won't check for CSRF token. You should never write to the database from GET
requests, for more information see the security guide on CSRF countermeasures.
Segment Constraints
You can use the :constraints
option to enforce a format for a dynamic segment:
get 'photos/:id', to: 'photos#show', constraints: { id: /[A-Z]\d{5}/ }
This route would match paths such as /photos/A12345
, but not /photos/893
. You can more succinctly express the same route this way:
get 'photos/:id', to: 'photos#show', id: /[A-Z]\d{5}/
:constraints
takes regular expressions with the restriction that regexp anchors can't be used. For example, the following route will not work:
get '/:id', to: 'articles#show', constraints: { id: /^\d/ }
However, note that you don't need to use anchors because all routes are anchored at the start and the end.
For example, the following routes would allow for articles
with to_param
values like 1-hello-world
that always begin with a number and users
with to_param
values like david
that never begin with a number to share the root namespace:
get '/:id', to: 'articles#show', constraints: { id: /\d.+/ }
get '/:username', to: 'users#show'
Request-Based Constraints
You can also constrain a route based on any method on the Request object that returns a String
.
You specify a request-based constraint the same way that you specify a segment constraint:
get 'photos', to: 'photos#index', constraints: { subdomain: 'admin' }
You can also specify constraints by using a constraints
block:
namespace :admin do
constraints subdomain: 'admin' do
resources :photos
end
end
NOTE: Request constraints work by calling a method on the Request object with the same name as the hash key and then comparing the return value with the hash value. Therefore, constraint values should match the corresponding Request object method return type. For example: constraints: { subdomain: 'api' }
will match an api
subdomain as expected. However, using a symbol constraints: { subdomain: :api }
will not, because request.subdomain
returns 'api'
as a String.
NOTE: There is an exception for the format
constraint: while it's a method on the Request object, it's also an implicit optional parameter on every path. Segment constraints take precedence and the format
constraint is only applied as such when enforced through a hash. For example, get 'foo', constraints: { format: 'json' }
will match GET /foo
because the format is optional by default. However, you can use a lambda like in get 'foo', constraints: lambda { |req| req.format == :json }
and the route will only match explicit JSON requests.
Advanced Constraints
If you have a more advanced constraint, you can provide an object that responds to matches?
that Rails should use. Let's say you wanted to route all users on a restricted list to the RestrictedListController
. You could do:
class RestrictedListConstraint
def initialize
@ips = RestrictedList.retrieve_ips
end
def matches?(request)
@ips.include?(request.remote_ip)
end
end
Rails.application.routes.draw do
get '*path', to: 'restricted_list#index',
constraints: RestrictedListConstraint.new
end
You can also specify constraints as a lambda:
Rails.application.routes.draw do
get '*path', to: 'restricted_list#index',
constraints: lambda { |request| RestrictedList.retrieve_ips.include?(request.remote_ip) }
end
Both the matches?
method and the lambda gets the request
object as an argument.
Constraints in a block form
You can specify constraints in a block form. This is useful for when you need to apply the same rule to several routes. For example
class RestrictedListConstraint
# ...Same as the example above
end
Rails.application.routes.draw do
constraints(RestrictedListConstraint.new) do
get '*path', to: 'restricted_list#index',
get '*other-path', to: 'other_restricted_list#index',
end
end
You also use a lambda
:
Rails.application.routes.draw do
constraints(lambda { |request| RestrictedList.retrieve_ips.include?(request.remote_ip) }) do
get '*path', to: 'restricted_list#index',
get '*other-path', to: 'other_restricted_list#index',
end
end
Route Globbing and Wildcard Segments
Route globbing is a way to specify that a particular parameter should be matched to all the remaining parts of a route. For example:
get 'photos/*other', to: 'photos#unknown'
This route would match photos/12
or /photos/long/path/to/12
, setting params[:other]
to "12"
or "long/path/to/12"
. The segments prefixed with a star are called "wildcard segments".
Wildcard segments can occur anywhere in a route. For example:
get 'books/*section/:title', to: 'books#show'
would match books/some/section/last-words-a-memoir
with params[:section]
equals 'some/section'
, and params[:title]
equals 'last-words-a-memoir'
.
Technically, a route can have even more than one wildcard segment. The matcher assigns segments to parameters in an intuitive way. For example:
get '*a/foo/*b', to: 'test#index'
would match zoo/woo/foo/bar/baz
with params[:a]
equals 'zoo/woo'
, and params[:b]
equals 'bar/baz'
.
NOTE: By requesting '/foo/bar.json'
, your params[:pages]
will be equal to 'foo/bar'
with the request format of JSON. If you want the old 3.0.x behavior back, you could supply format: false
like this:
get '*pages', to: 'pages#show', format: false
NOTE: If you want to make the format segment mandatory, so it cannot be omitted, you can supply format: true
like this:
get '*pages', to: 'pages#show', format: true
Redirection
You can redirect any path to another path using the redirect
helper in your router:
get '/stories', to: redirect('/articles')
You can also reuse dynamic segments from the match in the path to redirect to:
get '/stories/:name', to: redirect('/articles/%{name}')
You can also provide a block to redirect, which receives the symbolized path parameters and the request object:
get '/stories/:name', to: redirect { |path_params, req| "/articles/#{path_params[:name].pluralize}" }
get '/stories', to: redirect { |path_params, req| "/articles/#{req.subdomain}" }
Please note that default redirection is a 301 "Moved Permanently" redirect. Keep in mind that some web browsers or proxy servers will cache this type of redirect, making the old page inaccessible. You can use the :status
option to change the response status:
get '/stories/:name', to: redirect('/articles/%{name}', status: 302)
In all of these cases, if you don't provide the leading host (http://www.example.com
), Rails will take those details from the current request.
Routing to Rack Applications
Instead of a String like 'articles#index'
, which corresponds to the index
action in the ArticlesController
, you can specify any Rack application as the endpoint for a matcher:
match '/application.js', to: MyRackApp, via: :all
As long as MyRackApp
responds to call
and returns a [status, headers, body]
, the router won't know the difference between the Rack application and an action. This is an appropriate use of via: :all
, as you will want to allow your Rack application to handle all verbs as it considers appropriate.
NOTE: For the curious, 'articles#index'
actually expands out to ArticlesController.action(:index)
, which returns a valid Rack application.
If you specify a Rack application as the endpoint for a matcher, remember that
the route will be unchanged in the receiving application. With the following
route your Rack application should expect the route to be /admin
:
match '/admin', to: AdminApp, via: :all
If you would prefer to have your Rack application receive requests at the root
path instead, use mount
:
mount AdminApp, at: '/admin'
Using root
You can specify what Rails should route '/'
to with the root
method:
root to: 'pages#main'
root 'pages#main' # shortcut for the above
You should put the root
route at the top of the file, because it is the most popular route and should be matched first.
NOTE: The root
route only routes GET
requests to the action.
You can also use root inside namespaces and scopes as well. For example:
namespace :admin do
root to: "admin#index"
end
root to: "home#index"
Unicode Character Routes
You can specify unicode character routes directly. For example:
get 'こんにちは', to: 'welcome#index'
Direct Routes
You can create custom URL helpers directly by calling direct
. For example:
direct :homepage do
"http://www.rubyonrails.org"
end
# >> homepage_url
# => "http://www.rubyonrails.org"
The return value of the block must be a valid argument for the url_for
method. So, you can pass a valid string URL, Hash, Array, an Active Model instance, or an Active Model class.
direct :commentable do |model|
[ model, anchor: model.dom_id ]
end
direct :main do
{ controller: 'pages', action: 'index', subdomain: 'www' }
end
Using resolve
The resolve
method allows customizing polymorphic mapping of models. For example:
resource :basket
resolve("Basket") { [:basket] }
<%= form_with model: @basket do |form| %>
<!-- basket form -->
<% end %>
This will generate the singular URL /basket
instead of the usual /baskets/:id
.
Customizing Resourceful Routes
While the default routes and helpers generated by resources
will usually serve you well, you may want to customize them in some way. Rails allows you to customize virtually any generic part of the resourceful helpers.
Specifying a Controller to Use
The :controller
option lets you explicitly specify a controller to use for the resource. For example:
resources :photos, controller: 'images'
will recognize incoming paths beginning with /photos
but route to the Images
controller:
HTTP Verb | Path | Controller#Action | Named Route Helper |
---|---|---|---|
GET | /photos | images#index | photos_path |
GET | /photos/new | images#new | new_photo_path |
POST | /photos | images#create | photos_path |
GET | /photos/:id | images#show | photo_path(:id) |
GET | /photos/:id/edit | images#edit | edit_photo_path(:id) |
PATCH/PUT | /photos/:id | images#update | photo_path(:id) |
DELETE | /photos/:id | images#destroy | photo_path(:id) |
NOTE: Use photos_path
, new_photo_path
, etc. to generate paths for this resource.
For namespaced controllers you can use the directory notation. For example:
resources :user_permissions, controller: 'admin/user_permissions'
This will route to the Admin::UserPermissions
controller.
NOTE: Only the directory notation is supported. Specifying the
controller with Ruby constant notation (e.g. controller: 'Admin::UserPermissions'
)
can lead to routing problems and results in
a warning.
Specifying Constraints
You can use the :constraints
option to specify a required format on the implicit id
. For example:
resources :photos, constraints: { id: /[A-Z][A-Z][0-9]+/ }
This declaration constrains the :id
parameter to match the supplied regular expression. So, in this case, the router would no longer match /photos/1
to this route. Instead, /photos/RR27
would match.
You can specify a single constraint to apply to a number of routes by using the block form:
constraints(id: /[A-Z][A-Z][0-9]+/) do
resources :photos
resources :accounts
end
NOTE: Of course, you can use the more advanced constraints available in non-resourceful routes in this context.
TIP: By default the :id
parameter doesn't accept dots - this is because the dot is used as a separator for formatted routes. If you need to use a dot within an :id
add a constraint which overrides this - for example id: /[^\/]+/
allows anything except a slash.
Overriding the Named Route Helpers
The :as
option lets you override the normal naming for the named route helpers. For example:
resources :photos, as: 'images'
will recognize incoming paths beginning with /photos
and route the requests to PhotosController
, but use the value of the :as
option to name the helpers.
HTTP Verb | Path | Controller#Action | Named Route Helper |
---|---|---|---|
GET | /photos | photos#index | images_path |
GET | /photos/new | photos#new | new_image_path |
POST | /photos | photos#create | images_path |
GET | /photos/:id | photos#show | image_path(:id) |
GET | /photos/:id/edit | photos#edit | edit_image_path(:id) |
PATCH/PUT | /photos/:id | photos#update | image_path(:id) |
DELETE | /photos/:id | photos#destroy | image_path(:id) |
Overriding the new
and edit
Segments
The :path_names
option lets you override the automatically-generated new
and edit
segments in paths:
resources :photos, path_names: { new: 'make', edit: 'change' }
This would cause the routing to recognize paths such as:
/photos/make
/photos/1/change
NOTE: The actual action names aren't changed by this option. The two paths shown would still route to the new
and edit
actions.
TIP: If you find yourself wanting to change this option uniformly for all of your routes, you can use a scope.
scope path_names: { new: 'make' } do
# rest of your routes
end
Prefixing the Named Route Helpers
You can use the :as
option to prefix the named route helpers that Rails generates for a route. Use this option to prevent name collisions between routes using a path scope. For example:
scope 'admin' do
resources :photos, as: 'admin_photos'
end
resources :photos
This will provide route helpers such as admin_photos_path
, new_admin_photo_path
, etc.
To prefix a group of route helpers, use :as
with scope
:
scope 'admin', as: 'admin' do
resources :photos, :accounts
end
resources :photos, :accounts
This will generate routes such as admin_photos_path
and admin_accounts_path
which map to /admin/photos
and /admin/accounts
respectively.
NOTE: The namespace
scope will automatically add :as
as well as :module
and :path
prefixes.
You can prefix routes with a named parameter also:
scope ':username' do
resources :articles
end
This will provide you with URLs such as /bob/articles/1
and will allow you to reference the username
part of the path as params[:username]
in controllers, helpers, and views.
Restricting the Routes Created
By default, Rails creates routes for the seven default actions (index
, show
, new
, create
, edit
, update
, and destroy
) for every RESTful route in your application. You can use the :only
and :except
options to fine-tune this behavior. The :only
option tells Rails to create only the specified routes:
resources :photos, only: [:index, :show]
Now, a GET
request to /photos
would succeed, but a POST
request to /photos
(which would ordinarily be routed to the create
action) will fail.
The :except
option specifies a route or list of routes that Rails should not create:
resources :photos, except: :destroy
In this case, Rails will create all of the normal routes except the route for destroy
(a DELETE
request to /photos/:id
).
TIP: If your application has many RESTful routes, using :only
and :except
to generate only the routes that you actually need can cut down on memory use and speed up the routing process.
Translated Paths
Using scope
, we can alter path names generated by resources
:
scope(path_names: { new: 'neu', edit: 'bearbeiten' }) do
resources :categories, path: 'kategorien'
end
Rails now creates routes to the CategoriesController
.
HTTP Verb | Path | Controller#Action | Named Route Helper |
---|---|---|---|
GET | /kategorien | categories#index | categories_path |
GET | /kategorien/neu | categories#new | new_category_path |
POST | /kategorien | categories#create | categories_path |
GET | /kategorien/:id | categories#show | category_path(:id) |
GET | /kategorien/:id/bearbeiten | categories#edit | edit_category_path(:id) |
PATCH/PUT | /kategorien/:id | categories#update | category_path(:id) |
DELETE | /kategorien/:id | categories#destroy | category_path(:id) |
Overriding the Singular Form
If you want to define the singular form of a resource, you should add additional rules to the Inflector
via inflections
:
ActiveSupport::Inflector.inflections do |inflect|
inflect.irregular 'tooth', 'teeth'
end
Using :as
in Nested Resources
The :as
option overrides the automatically-generated name for the resource in nested route helpers. For example:
resources :magazines do
resources :ads, as: 'periodical_ads'
end
This will create routing helpers such as magazine_periodical_ads_url
and edit_magazine_periodical_ad_path
.
Overriding Named Route Parameters
The :param
option overrides the default resource identifier :id
(name of
the dynamic segment used to generate the
routes). You can access that segment from your controller using
params[<:param>]
.
resources :videos, param: :identifier
videos GET /videos(.:format) videos#index
POST /videos(.:format) videos#create
new_video GET /videos/new(.:format) videos#new
edit_video GET /videos/:identifier/edit(.:format) videos#edit
Video.find_by(identifier: params[:identifier])
You can override ActiveRecord::Base#to_param
of the associated model to construct
a URL:
class Video < ApplicationRecord
def to_param
identifier
end
end
video = Video.find_by(identifier: "Roman-Holiday")
edit_video_path(video) # => "/videos/Roman-Holiday/edit"
Breaking up very large route file into multiple small ones:
If you work in a large application with thousands of routes,
a single config/routes.rb
file can become cumbersome and hard to read.
Rails offers a way to break a gigantic single routes.rb
file into multiple small ones using the draw
macro.
# config/routes.rb
Rails.application.routes.draw do
get 'foo', to: 'foo#bar'
draw(:admin) # Will load another route file located in `config/routes/admin.rb`
end
# config/routes/admin.rb
namespace :admin do
resources :comments
end
Calling draw(:admin)
inside the Rails.application.routes.draw
block itself will try to load a route
file that has the same name as the argument given (admin.rb
in this case).
The file needs to be located inside the config/routes
directory or any sub-directory (i.e. config/routes/admin.rb
or config/routes/external/admin.rb
).
You can use the normal routing DSL inside the admin.rb
routing file, however you shouldn't surround it with the Rails.application.routes.draw
block like you did in the main config/routes.rb
file.
When to use and not use this feature
Drawing routes from external files can be very useful to organise a large set of routes into multiple organised ones. You could have a admin.rb
route that contains all the routes for the admin area, another api.rb
file to route API related resources etc...
However, you shouldn't abuse this feature as having too many route files make discoverability and understandability more difficult. Depending on the application, it might be easier for developers to have a single routing file even if you have few hundreds routes. You shouldn't try to create a new routing file for each category (admin, api ...) at all cost; the Rails routing DSL already offers a way to break routes in a organised manner with namespaces
and scopes
.
Inspecting and Testing Routes
Rails offers facilities for inspecting and testing your routes.
Listing Existing Routes
To get a complete list of the available routes in your application, visit http://localhost:3000/rails/info/routes
in your browser while your server is running in the development environment. You can also execute the bin/rails routes
command in your terminal to produce the same output.
Both methods will list all of your routes, in the same order that they appear in config/routes.rb
. For each route, you'll see:
- The route name (if any)
- The HTTP verb used (if the route doesn't respond to all verbs)
- The URL pattern to match
- The routing parameters for the route
For example, here's a small section of the bin/rails routes
output for a RESTful route:
users GET /users(.:format) users#index
POST /users(.:format) users#create
new_user GET /users/new(.:format) users#new
edit_user GET /users/:id/edit(.:format) users#edit
You can also use the --expanded
option to turn on the expanded table formatting mode.
$ bin/rails routes --expanded
--[ Route 1 ]----------------------------------------------------
Prefix | users
Verb | GET
URI | /users(.:format)
Controller#Action | users#index
--[ Route 2 ]----------------------------------------------------
Prefix |
Verb | POST
URI | /users(.:format)
Controller#Action | users#create
--[ Route 3 ]----------------------------------------------------
Prefix | new_user
Verb | GET
URI | /users/new(.:format)
Controller#Action | users#new
--[ Route 4 ]----------------------------------------------------
Prefix | edit_user
Verb | GET
URI | /users/:id/edit(.:format)
Controller#Action | users#edit
You can search through your routes with the grep option: -g. This outputs any routes that partially match the URL helper method name, the HTTP verb, or the URL path.
$ bin/rails routes -g new_comment
$ bin/rails routes -g POST
$ bin/rails routes -g admin
If you only want to see the routes that map to a specific controller, there's the -c option.
$ bin/rails routes -c users
$ bin/rails routes -c admin/users
$ bin/rails routes -c Comments
$ bin/rails routes -c Articles::CommentsController
TIP: You'll find that the output from bin/rails routes
is much more readable if you widen your terminal window until the output lines don't wrap.
Testing Routes
Routes should be included in your testing strategy (just like the rest of your application). Rails offers three built-in assertions designed to make testing routes simpler:
The assert_generates
Assertion
assert_generates
asserts that a particular set of options generate a particular path and can be used with default routes or custom routes. For example:
assert_generates '/photos/1', { controller: 'photos', action: 'show', id: '1' }
assert_generates '/about', controller: 'pages', action: 'about'
The assert_recognizes
Assertion
assert_recognizes
is the inverse of assert_generates
. It asserts that a given path is recognized and routes it to a particular spot in your application. For example:
assert_recognizes({ controller: 'photos', action: 'show', id: '1' }, '/photos/1')
You can supply a :method
argument to specify the HTTP verb:
assert_recognizes({ controller: 'photos', action: 'create' }, { path: 'photos', method: :post })
The assert_routing
Assertion
The assert_routing
assertion checks the route both ways: it tests that the path generates the options, and that the options generate the path. Thus, it combines the functions of assert_generates
and assert_recognizes
:
assert_routing({ path: 'photos', method: :post }, { controller: 'photos', action: 'create' })