PhoneGap Mobile Rails Authentication (devise? authentication from scratch?) - ruby-on-rails

Question

I have a PhoneGap app with a Rails backend. I'm trying to figure out what the best way is to authenticate a user from the mobile app using json.
I am using devise currently, but I don't have to use that. What would be the most simple way to modify devise to work with a mobile app in Phonegap?
I know there are quite a few posts on this... but, some of them are outdated or seem like very complex hacks. Hoping there may be more up to date info from some tried and tested projects, or tutorials.
One post I found also suggests using jsonp, but it also seemed like a pretty complex hack. You can find it here: http://vimeo.com/18763953
I'm also wondering if I would just be better off starting out with authentication from scratch, as laid out in this Railscast: http://railscasts.com/episodes/250-authentication-from-scratch
Thanks!

Answer 1

You should override devise's sessions and registrations controller. I'll only show you how to override the sessions controller:
First, go to your User model and add the Token Authenticatable module. Something like this:
devise :token_authenticatable
before_save :ensure_authentication_token
Then edit your devise.rb file to configure that module:
# You can skip storage for :http_auth and :token_auth by adding those symbols to the array below.
config.skip_session_storage = [:token_auth]
# Defines name of the authentication token params key
config.token_authentication_key = :auth_token
Now edit your routes and point to your new controllers:
devise_for :users, :controllers => { :registrations => 'registrations', :sessions => 'sessions' }
And then create your controller like this:
class SessionsController < Devise::SessionsController
def create
respond_to do |format|
format.html {
super
}
format.json {
build_resource
user = User.find_for_database_authentication(:email => params[:user][:email])
return invalid_login_attempt unless resource
if user.valid_password?(params[:user][:password])
render :json => { :auth_token => user.authentication_token }, success: true, status: :created
else
invalid_login_attempt
end
}
end
end
def destroy
respond_to do |format|
format.html {
super
}
format.json {
user = User.find_by_authentication_token(params[:auth_token])
if user
user.reset_authentication_token!
render :json => { :message => 'Session deleted.' }, :success => true, :status => 204
else
render :json => { :message => 'Invalid token.' }, :status => 404
end
}
end
end
protected
def invalid_login_attempt
warden.custom_failure!
render json: { success: false, message: 'Error with your login or password' }, status: 401
end
end
Devise has a page about this, but it only points to some already outdated guides. But maybe it will help you.