Organize Rails routing using draw

Introduction

In routes.rb of gitlab, I found something like draw: api and found it very useful, so I will summarize it.

draw

If you write something like draw: api, it will read the routes described in config/routes/api.rb.

For example, you can make it easier to understand by writing the routing in a separate file for each namespace.

It is not prepared by default, but it was prepared independently in the source code of gitlab, so some preparation is required.

Preparation

Create a draw_routes.rb file under config/initializers and describe the following contents.

It's almost the same as the gitlab source code.

module DrawRoute
  RoutesNotFound = Class.new(StandardError)

  def draw(routes_name)
    drawn_any = draw_route(routes_name)

    drawn_any || raise(RoutesNotFound, "Cannot find #{routes_name}")
  end

  def route_path(routes_name)
    Rails.root.join(routes_name)
  end

  def draw_route(routes_name)
    path = route_path("config/routes/#{routes_name}.rb")
    if File.exist?(path)
      instance_eval(File.read(path))
      true
    else
      false
    end
  end
end

ActionDispatch::Routing::Mapper.prepend DrawRoute

Example of use

Cut out the routes of the management screen

Create admin.rb under config/routes and describe as below

namespace :admin do
  resources :users
end

in routes.rb

Rails.application.routes.draw do
  draw :admin
end

By describing, routes will be created as shown below.

                          admin_users GET    /admin/users(.:format)                                                                   admin/users#index
                                      POST   /admin/users(.:format)                                                                   admin/users#create
                       new_admin_user GET    /admin/users/new(.:format)                                                               admin/users#new
                      edit_admin_user GET    /admin/users/:id/edit(.:format)                                                          admin/users#edit
                           admin_user GET    /admin/users/:id(.:format)                                                               admin/users#show
                                      PATCH  /admin/users/:id(.:format)                                                               admin/users#update
                                      PUT    /admin/users/:id(.:format)                                                               admin/users#update
                                      DELETE /admin/users/:id(.:format)                                                               admin/users#destroy

Usage example 2

Cut out the routes of the larger model.

For example, if you have users_controller.rb and users/licenses_controller.rb users/activates_controller.rb, group them into folders for each user.

config/routes/user.rb

resources :users do
  scope module: :users do
    resource :activates, only: %i[update destroy]
    resources :licences
  end
end

And by reading in routes.rb

Rails.application.routes.draw do
  draw :user
end

The following routing will be created.

                       user_activates PATCH  /users/:user_id/activates(.:format)                                                      users/activates#update
                                      PUT    /users/:user_id/activates(.:format)                                                      users/activates#update
                                      DELETE /users/:user_id/activates(.:format)                                                      users/activates#destroy
                             licences GET    /users/licences(.:format)                                                                users/licences#index
                                      POST   /users/licences(.:format)                                                                users/licences#create
                          new_licence GET    /users/licences/new(.:format)                                                            users/licences#new
                         edit_licence GET    /users/licences/:id/edit(.:format)                                                       users/licences#edit
                              licence GET    /users/licences/:id(.:format)                                                            users/licences#show
                                      PATCH  /users/licences/:id(.:format)                                                            users/licences#update
                                      PUT    /users/licences/:id(.:format)                                                            users/licences#update
                                      DELETE /users/licences/:id(.:format)                                                            users/licences#destroy
                                users GET    /users(.:format)                                                                         users#index

At the end

As the app grows, routes.rb can become chaotic, so using draw to nicely separate the files seems to be neat.