Automatically log in on merb-auth account creation

Recently I was adding new user registration to tasteb.in and I wanted my users to be automatically logged in as soon as they created their account. I’m using merb for tasteb.in, and consequently merb-auth for authentication. It turns out it’s really easy to implement, but it took me a while to get it right. All you need to do is add the following to your action that creates the new user:

session.user = @user

That’s it. All you must do is set the user in the session to the newly created user. I hope this saves somebody else some time.