Rails is a great framework! When you start building web apps with it, you will definitely fall in love with it!

Today I want to share with you one really cool feature - you have hooks (called Filters in Rails) that allow you to execute code before, after or around a controller action.

One of the cases I had was to validate the validity of the Authorization token in the headers before the requested action being executed. There're two cases: either the token is valid nor invalid. If it's the first case - the request is passed to the action, if it's the second - an error JSON and respective status code are returned as response.

So, lets see how I accomplished this task!

First, you have to create a method which will execute the validation logic. I called it validate_auth_token:

def validate_auth_token
  if request.headers["Authorization"].blank?
    render json: {'status_code': 403, message: 'Missing or wrong authentication token'}, status: 403 and return
  end
end

Then you have to tell the controller that you want to execute this method before each action. This is pretty easy! Just add at the controller's top:

class ApiController < ActionController::API
  before_action : validate_auth_token
  ...
end

That's it! Really easy, right? 👻

For more information - review the official Ruby on Rails Documentation.