Feb 28 2016

Setting Up Rails 5 API Only App with ActiveAdmin enabled

Note: This article is out of date since Rails 5 has been already released. Here is an updated version of this article.

---

A new version of Rails 5.0 beta 3 was published several days ago while the final version is to be released on March 16. It means we can start playing with it right now! Yay!!

As you may probably know rails-api gem is now shipped with rails 5 by default. It means that we can create beautiful API services using rails without any doubt =)

If you missed the announcement on what’s new in Rails 5, checkout the rails 5.0.0 anounce

Rails is … a great companion for the new crop of client-side JavaScript or native applications that just needs the backend to speak JSON. We’ve made this even clearer now with the new –api mode. If you create a new Rails application using rails new backend –api, you’ll get a slimmed down skeleton and configuration that assumes you’ll be working with JSON, not HTML.

Generating an API application stripes down Rails a lot, disabling views, flash messages, cookies, and more more, but ActiveAdmin can still be plugged into it with a bit of tweaking. So here is the steps on how to create a new Rails-5 API application with ActiveAdmin integration:

Setting Up Rails Api

1. Make sure you have installed Ruby 2.2.2 or newer as it is required by Rails 5. I use Ruby 2.3.0 as it was recently released as well and I want to try it out.

   1
   2
   3
   4
   5
   6
   7
   8
   9
   10
     $ rvm list
       rvm rubies
          ruby-1.9.3-p551 [ x86_64 ]
          ruby-2.1.7 [ x86_64 ]
       *  ruby-2.2.4 [ x86_64 ]
       => ruby-2.3.0 [ x86_64 ]
   
       # => - current
       # =* - current && default
       #  * - default
   

2. Rails 5 hasn’t been officially released yet so we have to clone Rails from its GitHub repository(master branch):

   1
     $ git clone git@github.com:rails/rails.git
   

3. Go into the newly cloned rails dir, and run the bundle command.

   1
     $ bundle install
   

4. To start building a new Rails API project, we need to generate it by passing the --api parameter to the rails new command:

   1
     $ bundle exec railties/exe/rails new ../new_api_app --api --edge
   

   I am running this command from the directory where cloned version of rails is located. It means I have to put an additional param with the directory name started from ../ to put the newly generated application into a place above current wd. ../new_api_app in this case.

5. The next step is to cd into directory of your new rails API application and run bundle and rake db:setup to install all the necessary gems and setup the database:

   1
   2
   3
     $ cd ../new_api_app
     $ bundle install
     $ bin/rake db:setup
   

   Note that I am using bin/rake(and will be using bin/rails in the next steps) cause this version of rails was not installed globally and the full path to appropriate binary should be used.

   Now we have a new tiny-tyne API only Rails application without tons of Front-end related stuff that is useless in case of API apps.

6. The very next step would be: installing and setting up RSpec, adding tests, scaffolding resources, etc, etc, but this part is out of my theme.

   You have probably noted that when an app is created with the --api flag, generator did not create views but only api-related resources were created, e.g.:

   1
   2
   3
   4
   5
   6
   7
   8
   9
   10
   11
   12
   13
   14
   15
   16
   17
   18
   19
   20
     $ bin/rails g scaffold user
       Running via Spring preloader in process 55287
         invoke  active_record
         create    db/migrate/20160228093108_create_users.rb
         create    app/models/user.rb
         invoke    rspec
         create      spec/models/user_spec.rb
         invoke      factory_girl
         create        spec/factories/users.rb
         invoke  resource_route
          route    resources :users
         invoke  serializer
         create    app/serializers/user_serializer.rb
         invoke  scaffold_controller
         create    app/controllers/users_controller.rb
         invoke    rspec
         create      spec/controllers/users_controller_spec.rb
         create      spec/routing/users_routing_spec.rb
         invoke      rspec
         create        spec/requests/users_spec.rb
   

---

Adding ActiveAdmin to Rails 5 API app

Even thought Rails 5 API allows us to get rid of senseless Rails’ Front-End parts, generating a new project using --api param, we can easily integrate ActiveAdmin into it.

They did it by having base API controller inherit from ActionController::API instead of ApplicationController so integrating ActiveAdmin is as easy as setting ApplicationController to be inherited from ActionController::Base.

We also need to include several classes to the middleware to make it working.

Let’s do it!

Prepare Rails API application.

1. Update your application_controller.rb file.

   before:

   1
   2
   3
     class ApplicationController < ActionController::API
       # your code here
     end
   

   after:

   1
   2
   3
     class ApplicationController < ActionController::Base
       # your code here
     end
   

2. Update config/application.rb file to include necessary for ActiveAdmin ActionDispatch::Flash, Rack::MethodOverride and ActionDispatch::Cookies

   1
   2
   3
   4
   5
   6
   7
   8
     module NewApiApp
       class Application < Rails::Application
         # ...
         config.middleware.use ActionDispatch::Flash
         config.middleware.use Rack::MethodOverride
         config.middleware.use ActionDispatch::Cookies
       end
     end
   

Note: This way your main application code is still API only with all its benefits but you will be able to use ActiveAdmin and it should work as expected.

Install ActiveAdmin

1. Add ActiveAdmin to your Gemfile:

   1
   2
   3
     source 'https://rubygems.org'
     # ...
     gem 'activeadmin', github: 'activeadmin'
   

2. ActiveAdmin master has preliminary support for Rails 5 and to give it a try, these Gems should be installed:

   1
   2
   3
   4
   5
   6
   7
   8
   9
   10
   11
   12
   13
     gem 'devise',      '> 4.x'
     gem 'rspec-rails', '>= 3.5.0.beta1'
     gem 'ransack',    github: 'activerecord-hackery/ransack'
     gem 'kaminari',   github: 'amatsuda/kaminari', branch: '0-17-stable'
     gem 'formtastic', github: 'justinfrench/formtastic'
     gem 'draper',     github: 'audionerd/draper', branch: 'rails5', ref: 'e816e0e587'
   
     # To fix a Draper deprecation error
     gem 'activemodel-serializers-xml', github: 'rails/activemodel-serializers-xml'
   
     # Optional -- only if you already include these gems
     gem 'rack-mini-profiler',          github: 'MiniProfiler/rack-mini-profiler'
     gem 'database_cleaner',            github: 'pschambacher/database_cleaner', branch: 'rails5.0', ref: '8dd9fa4'
   

3. Update gems using bundler:

   1
     $ bundle install
   

4. After installing the gems, you need to run the generator.

   1
     $ bin/rails g active_admin:install
   

   Here are another options, like setting it to use an existing user class: activeadmin/docs/0-installation.md

5. Update your migrations and start rails to the results:

   1
   2
   3
     $ rake db:migrate
     $ rake db:seed
     $ rails server
   

   Visit http://localhost:3000/admin and log in as the default user:

   User: admin@example.com Password: password

That’s it. =)

Don’t forget to isolate your admin page to protect it from attacks. You can, for example, filter out access to it so it is available from your internal IP address only.

Keep having a good day!