# File actionpack/lib/action_dispatch/routing/mapper.rb, line 654
def has_named_route?(name)
  @set.named_routes.key?(name)
end

Query if the following named route was already defined.

# File actionpack/lib/action_dispatch/routing/mapper.rb, line 590
def match(path, options = nil)
end

Matches a URL pattern to one or more routes.

You should not use the match method in your router without specifying an HTTP method.

If you want to expose your action to both GET and POST, use:

# sets :controller, :action and :id in params
match ':controller/:action/:id', via: [:get, :post]

Note that :controller, :action and :id are interpreted as URL query parameters and thus available through params in an action.

If you want to expose your action to GET, use get in the router:

Instead of:

match ":controller/:action/:id"

Do:

get ":controller/:action/:id"

Two of these symbols are special, :controller maps to the controller and :action to the controller's action. A pattern can also map wildcard segments (globs) to params:

get 'songs/*category/:title', to: 'songs#show'

# 'songs/rock/classic/stairway-to-heaven' sets
#  params[:category] = 'rock/classic'
#  params[:title] = 'stairway-to-heaven'

To match a wildcard parameter, it must have a name assigned to it. Without a variable name to attach the glob parameter to, the route can't be parsed.

When a pattern points to an internal route, the route's :action and :controller should be set in options or hash shorthand. Examples:

match 'photos/:id' => 'photos#show', via: :get
match 'photos/:id', to: 'photos#show', via: :get
match 'photos/:id', controller: 'photos', action: 'show', via: :get

A pattern can also point to a Rack endpoint i.e. anything that responds to call:

match 'photos/:id', to: -> (hash) { [200, {}, ["Coming soon"]] }, via: :get
match 'photos/:id', to: PhotoRackApp, via: :get
# Yes, controller actions are just rack endpoints
match 'photos/:id', to: PhotosController.action(:show), via: :get

Because requesting various HTTP verbs with a single action has security implications, you must either specify the actions in the via options or use one of the HttpHelpers instead match

Options

Any options not seen here are passed on as params with the URL.

:controller

The route's controller.

:action

The route's action.

:param

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>]. In your router:

resources :users, param: :name

The users resource here will have the following routes generated for it:

GET       /users(.:format)
POST      /users(.:format)
GET       /users/new(.:format)
GET       /users/:name/edit(.:format)
GET       /users/:name(.:format)
PATCH/PUT /users/:name(.:format)
DELETE    /users/:name(.:format)

You can override ActiveRecord::Base#to_param of a related model to construct a URL:

class User < ActiveRecord::Base
  def to_param
    name
  end
end

user = User.find_by(name: 'Phusion')
user_path(user)  # => "/users/Phusion"

:path

The path prefix for the routes.

:module

The namespace for :controller.

match 'path', to: 'c#a', module: 'sekret', controller: 'posts', via: :get
# => Sekret::PostsController

See Scoping#namespace for its scope equivalent.

:as

The name used to generate routing helpers.

:via

Allowed HTTP verb(s) for route.

match 'path', to: 'c#a', via: :get
match 'path', to: 'c#a', via: [:get, :post]
match 'path', to: 'c#a', via: :all

:to

Points to a Rack endpoint. Can be an object that responds to call or a string representing a controller's action.

match 'path', to: 'controller#action', via: :get
match 'path', to: -> (env) { [200, {}, ["Success!"]] }, via: :get
match 'path', to: RackApp, via: :get

:on

Shorthand for wrapping routes in a specific RESTful context. Valid values are :member, :collection, and :new. Only use within resource(s) block. For example:

resource :bar do
  match 'foo', to: 'c#a', on: :member, via: [:get, :post]
end

Is equivalent to:

resource :bar do
  member do
    match 'foo', to: 'c#a', via: [:get, :post]
  end
end

:constraints

Constrains parameters with a hash of regular expressions or an object that responds to matches?. In addition, constraints other than path can also be specified with any object that responds to === (eg. String, Array, Range, etc.).

match 'path/:id', constraints: { id: /[A-Z]\d{5}/ }, via: :get

match 'json_only', constraints: { format: 'json' }, via: :get

class PermitList
  def matches?(request) request.remote_ip == '1.2.3.4' end
end
match 'path', to: 'c#a', constraints: PermitList.new, via: :get

See Scoping#constraints for more examples with its scope equivalent.

:defaults

Sets defaults for parameters

# Sets params[:format] to 'jpg' by default
match 'path', to: 'c#a', defaults: { format: 'jpg' }, via: :get

See Scoping#defaults for its scope equivalent.

:anchor

Boolean to anchor a match pattern. Default is true. When set to false, the pattern matches any request prefixed with the given path.

# Matches any request starting with 'path'
match 'path', to: 'c#a', anchor: false, via: :get

:format

Allows you to specify the default value for optional format segment or disable it by supplying false.

# File actionpack/lib/action_dispatch/routing/mapper.rb, line 612
        def mount(app, options = nil)
          if options
            path = options.delete(:at)
          elsif Hash === app
            options = app
            app, path = options.find { |k, _| k.respond_to?(:call) }
            options.delete(app) if app
          end

          raise ArgumentError, "A rack application must be specified" unless app.respond_to?(:call)
          raise ArgumentError, <<~MSG unless path
            Must be called with mount point

              mount SomeRackApp, at: "some_route"
              or
              mount(SomeRackApp => "some_route")
          MSG

          rails_app = rails_app? app
          options[:as] ||= app_name(app, rails_app)

          target_as       = name_for_action(options[:as], path)
          options[:via] ||= :all

          match(path, options.merge(to: app, anchor: false, format: false))

          define_generate_prefix(app, target_as) if rails_app
          self
        end

Mount a Rack-based application to be used within the application.

mount SomeRackApp, at: "some_route"

Alternatively:

mount(SomeRackApp => "some_route")

For options, see match, as mount uses it internally.

All mounted applications come with routing helpers to access them. These are named after the class specified, so for the above example the helper is either some_rack_app_path or some_rack_app_url. To customize this helper's name, use the :as option:

mount(SomeRackApp => "some_route", as: "exciting")

This will generate the exciting_path and exciting_url helpers which can be used to navigate to this mounted app.