undefined method `devise_for' in rails

Solution 1:

Remember to restart your rails server after installing and configuring devise.

Solution 2:

If you have the Devise gem specified in the Gemfile, just make sure you have the following in your routes.rb file:

 devise_for :users

Also, here's a trick to make sure Devise is mapped properly, run: rails c, (the Rails app console) in your app's folder and then the following command line:

 Devise.mappings.keys

You should see:

=> [:user] 

Cheers!

Solution 3:

Honestly, I would recommend following these two Railscasts (Episode 209 and Episode 210). The first is a simple and very easy walkthrough for installing Devise and the second is about customizing it to fit your application.

I've watched both episodes and they drastically helped me with Devise, particularly with the customization.

Your best bet is to start from scratch - you'll learn a heck of a lot and have Devise fully installed and functional.

Hope this helps! Good luck.