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Note: This article is out of date since Rails 5 has been already released.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

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.

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  $ 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

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

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

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

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  $ bundle install

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

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.:

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  $ 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.

Update your application_controller.rb file.

before:

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  class ApplicationController < ActionController::API
    # your code here
  end

after:

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  class ApplicationController < ActionController::Base
    # your code here
  end

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

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  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

Add ActiveAdmin to your Gemfile:

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

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

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  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'

Update gems using bundler:

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  $ bundle install

After installing the gems, you need to run the generator.
```
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  $ bin/rails g active_admin:install
```
Here are another options, like setting it to use an existing user class: activeadmin/docs/0-installation.md

Update your migrations and start rails to the results:

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  $ 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.

Setting Up Rails 5 API Only App with ActiveAdmin enabled

Setting Up Rails Api

Adding ActiveAdmin to Rails 5 API app

Prepare Rails API application.

Install ActiveAdmin

Keep having a good day!