Rails api gem and devise token authentication

Question

If someone could shed some light It would be greatly appreciated as I'm bit clueless on this issue. Basically I'm trying to get the devise authentication done with a JSON only rails rest api app built on top of rails-api gem.

I've already implemented the Sessions and Registrations handling as described below.

class ApplicationController < ActionController::API
    include ActionController::MimeResponds
end

sessions_controller.rb

  class SessionsController < Devise::SessionsController
    prepend_before_filter :require_no_authentication, :only => [:create ]

    before_filter :ensure_params_exist
    def create
      build_resource
      resource = User.find_for_database_authentication(:email => params[:user][:email])
      return invalid_login_attempt unless resource

      if resource.valid_password?(params[:user][:password])
        sign_in("user", resource)
        render :json=> {:success=>true, :auth_token=>resource.authentication_token, :email=>resource.email}
      return
      end
      invalid_login_attempt
    end

    def destroy
      sign_out(resource_name)
    end

    protected

    def ensure_params_exist
      return unless params[:user][:email].blank?
      render :json=>{:success=>false, :message=>"missing login email parameter"}, :status=>422
    end

    def invalid_login_attempt
      warden.custom_failure!
      render :json=> {:success=>false, :message=>"Error with your login or password"}, :status=>401
    end

  end

registrations_controller.rb

  class RegistrationsController < Devise::RegistrationsController
    skip_before_filter :verify_authenticity_token, :only => :create

    def create
      user = User.new(params[:user])
      if user.save
        render :json=> {:user => [:email => user.email, :auth_token => user.authentication_token]}, :status => 201
      return
      else
        warden.custom_failure!
        render :json=> user.errors, :status=>422
      end
    end
  end

Everything works fine so far. In my other controllers I've added this line to secure them. before_filter :authenticate_user! but I get this error when calling with auth_token. ?auth_token=xxxxxxxxxxx

undefined method authenticate_user!

controllers

class RestaurantsController < ApplicationController

        before_filter :authenticate_user!

      def index
        @restaurants =  Restaurant.all

      end

      def show
        @restaurant = Restaurant.find(params[:id])

      end
    end

Still not sure what might be the issue here - I'm assuming this is happening because something is missing to work devise properly as its using ActionController::API

UPDATE It seems the issue is with my routes.rb itself - This is how the routes are done.

require 'api_constraints'

MyApi::Application.routes.draw do

  namespace :api, defaults: {format: 'json'} do
    scope module: :v1, constraints: ApiConstraints.new(version: 1,default: true) do
      devise_for :users
      resources :friends
      resources :locations
      resources :profiles
      resources :users


    end

    scope module: :v2, constraints: ApiConstraints.new(version: 2) do
    # Future releases of the API can go here
    end

  end

end

Now If repeat the devise_for :users outside the scope everything started working.

require 'api_constraints'

MyApi::Application.routes.draw do

  namespace :api, defaults: {format: 'json'} do
    scope module: :v1, constraints: ApiConstraints.new(version: 1,default: true) do
      devise_for :users
      resources :friends
      resources :locations
      resources :profiles
      resources :users


    end

    scope module: :v2, constraints: ApiConstraints.new(version: 2) do
    # Future releases of the API can go here
    end

  end
devise_for :users
end

Does any one has an explanation why?

Answer 1

Step 1. Override devise controllers with custom controllers that replace redirects with JSON responses. Here's a custom SessionController that uses JSON responses .

Step 2. If an authentication error occurs, the control goes to warden which uses a failure_app which is nothing but a Rack application which sets the flash messages and renders/redirects based on the requested format. You need a custom json response with an errors key holding an array of errors instead of the default error key. So you need a custom_auth_failure_app.rb under config/initializers with this content.

Step 4. Now we have to tell Devise to use the custom failure app by adding this to config/initializers/devise.rb :

config.warden do |manager|
  manager.failure_app = CustomAuthFailure
end

Step 5. Enable token_authenticatable in the devise model and add the following to config/initializers/devise.rb

config.http_authenticatable = true
config.skip_session_storage = [:http_auth, :token_auth]

Step 6. If you are using a true JSON API which doesn't use session, use a version of warden ( > 1.2.2 ) which has patches to handle a nil session.

Also read my blog post about creating a tested, documented and versioned JSON API using Rails4 + Rails-API + Devise which talks about all these steps.