module ActionDispatch::Routing::Mapper::Resources

# File actionpack/lib/action_dispatch/routing/mapper.rb, line 1506
def collection
  unless resource_scope?
    raise ArgumentError, "can't use collection outside resource(s) scope"
  end

  with_scope_level(:collection) do
    path_scope(parent_resource.collection_scope) do
      yield
    end
  end
end

To add a route to the collection:

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.

# File actionpack/lib/action_dispatch/routing/mapper.rb, line 1603
def match(path, *rest, &block)
  if rest.empty? && Hash === path
    options  = path
    path, to = options.find { |name, _value| name.is_a?(String) }

    raise ArgumentError, "Route path not specified" if path.nil?

    case to
    when Symbol
      options[:action] = to
    when String
      if /#/.match?(to)
        options[:to] = to
      else
        options[:controller] = to
      end
    else
      options[:to] = to
    end

    options.delete(path)
    paths = [path]
  else
    options = rest.pop || {}
    paths = [path] + rest
  end

  if options.key?(:defaults)
    defaults(options.delete(:defaults)) { map_match(paths, options, &block) }
  else
    map_match(paths, options, &block)
  end
end

Matches a URL pattern to one or more routes. For more information, see match.

match 'path' => 'controller#action', via: :patch
match 'path', to: 'controller#action', via: :post
match 'path', 'otherpath', on: :member, via: :get

# File actionpack/lib/action_dispatch/routing/mapper.rb, line 1529
def member
  unless resource_scope?
    raise ArgumentError, "can't use member outside resource(s) scope"
  end

  with_scope_level(:member) do
    if shallow?
      shallow_scope {
        path_scope(parent_resource.member_scope) { yield }
      }
    else
      path_scope(parent_resource.member_scope) { yield }
    end
  end
end

To add a member route, 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. It will also create the preview_photo_url and preview_photo_path helpers.

# File actionpack/lib/action_dispatch/routing/mapper.rb, line 1578
def namespace(path, options = {})
  if resource_scope?
    nested { super }
  else
    super
  end
end

See ActionDispatch::Routing::Mapper::Scoping#namespace.

# File actionpack/lib/action_dispatch/routing/mapper.rb, line 1298
def resource(*resources, &block)
  options = resources.extract_options!.dup

  if apply_common_behavior_for(:resource, resources, options, &block)
    return self
  end

  with_scope_level(:resource) do
    options = apply_action_options options
    resource_scope(SingletonResource.new(resources.pop, api_only?, @scope[:shallow], options)) do
      yield if block_given?

      concerns(options[:concerns]) if options[:concerns]

      new do
        get :new
      end if parent_resource.actions.include?(:new)

      set_member_mappings_for_resource

      collection do
        post :create
      end if parent_resource.actions.include?(:create)
    end
  end

  self
end

Sometimes, you have a resource that clients always look up without referencing an ID. A common example, /profile always shows 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:

resource :profile

This creates six different routes in your application, all mapping to the Profiles controller (note that the controller is named after the plural):

GET       /profile/new
GET       /profile
GET       /profile/edit
PATCH/PUT /profile
DELETE    /profile
POST      /profile

Options

Takes same options as resources

# File actionpack/lib/action_dispatch/routing/mapper.rb, line 1464
def resources(*resources, &block)
  options = resources.extract_options!.dup

  if apply_common_behavior_for(:resources, resources, options, &block)
    return self
  end

  with_scope_level(:resources) do
    options = apply_action_options options
    resource_scope(Resource.new(resources.pop, api_only?, @scope[:shallow], options)) do
      yield if block_given?

      concerns(options[:concerns]) if options[:concerns]

      collection do
        get  :index if parent_resource.actions.include?(:index)
        post :create if parent_resource.actions.include?(:create)
      end

      new do
        get :new
      end if parent_resource.actions.include?(:new)

      set_member_mappings_for_resource
    end
  end

  self
end

In Rails, a resourceful route provides a mapping between HTTP verbs and URLs and controller actions. By convention, each action also maps to particular CRUD operations 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:

GET       /photos
GET       /photos/new
POST      /photos
GET       /photos/:id
GET       /photos/:id/edit
PATCH/PUT /photos/:id
DELETE    /photos/:id

Resources can also be nested infinitely by using this block syntax:

resources :photos do
  resources :comments
end

This generates the following comments routes:

GET       /photos/:photo_id/comments
GET       /photos/:photo_id/comments/new
POST      /photos/:photo_id/comments
GET       /photos/:photo_id/comments/:id
GET       /photos/:photo_id/comments/:id/edit
PATCH/PUT /photos/:photo_id/comments/:id
DELETE    /photos/:photo_id/comments/:id

Options

Takes same options as match as well as:

:path_names

Allows you to change the segment component of the edit and new actions. Actions not specified are not changed.

resources :posts, path_names: { new: "brand_new" }

The above example will now change /posts/new to /posts/brand_new.

:path

Allows you to change the path prefix for the resource.

resources :posts, path: 'postings'

The resource and all segments will now route to /postings instead of /posts.

:only

Only generate routes for the given actions.

resources :cows, only: :show
resources :cows, only: [:show, :index]

:except

Generate all routes except for the given actions.

resources :cows, except: :show
resources :cows, except: [:show, :index]

:shallow

Generates shallow routes for nested resource(s). When placed on a parent resource, generates shallow routes for all nested resources.

resources :posts, shallow: true do
  resources :comments
end

Is the same as:

resources :posts do
  resources :comments, except: [:show, :edit, :update, :destroy]
end
resources :comments, only: [:show, :edit, :update, :destroy]

This allows URLs for resources that otherwise would be deeply nested such as a comment on a blog post like /posts/a-long-permalink/comments/1234 to be shortened to just /comments/1234.

Set shallow: false on a child resource to ignore a parent's shallow parameter.

:shallow_path

Prefixes nested shallow routes with the specified path.

scope shallow_path: "sekret" do
  resources :posts do
    resources :comments, shallow: true
  end
end

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

post_comments    GET       /posts/:post_id/comments(.:format)
post_comments    POST      /posts/:post_id/comments(.:format)
new_post_comment GET       /posts/:post_id/comments/new(.:format)
edit_comment     GET       /sekret/comments/:id/edit(.:format)
comment          GET       /sekret/comments/:id(.:format)
comment          PATCH/PUT /sekret/comments/:id(.:format)
comment          DELETE    /sekret/comments/:id(.:format)

:shallow_prefix

Prefixes nested shallow route names with specified prefix.

scope shallow_prefix: "sekret" do
  resources :posts do
    resources :comments, shallow: true
  end
end

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

post_comments           GET       /posts/:post_id/comments(.:format)
post_comments           POST      /posts/:post_id/comments(.:format)
new_post_comment        GET       /posts/:post_id/comments/new(.:format)
edit_sekret_comment     GET       /comments/:id/edit(.:format)
sekret_comment          GET       /comments/:id(.:format)
sekret_comment          PATCH/PUT /comments/:id(.:format)
sekret_comment          DELETE    /comments/:id(.:format)

:format

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

:param

Allows you to override the default param name of :id in the URL.

Examples

# routes call <tt>Admin::PostsController</tt>
resources :posts, module: "admin"

# resource actions are at /admin/posts.
resources :posts, path: "admin/posts"

# File actionpack/lib/action_dispatch/routing/mapper.rb, line 1650
def root(path, options = {})
  if path.is_a?(String)
    options[:to] = path
  elsif path.is_a?(Hash) && options.empty?
    options = path
  else
    raise ArgumentError, "must be called with a path and/or options"
  end

  if @scope.resources?
    with_scope_level(:root) do
      path_scope(parent_resource.path) do
        match_root_route(options)
      end
    end
  else
    match_root_route(options)
  end
end

You can specify what Rails should route “/” to with the root method:

root to: 'pages#main'

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

You can also pass a string which will expand

root 'pages#main'

You should put the root route at the top of config/routes.rb, because this means it will be matched first. As this is the most popular route of most Rails applications, this is beneficial.