NoMethodError after loggin in in Ruby on Rails networking website

I'm trying to make an example of a small networking site, and when I log in a user, it should redirect and show his profile, but I get the following error:

NoMethodError in User#index

Show开发者_运维知识库ing app/views/user/index.html.erb where line #5 raised:

undefined method `screen_name' for nil:NilClass Extracted source (around line #5):

2: Your basic information 3: 4:

5:
• Screen name: <%= @user.screen_name %>
6:
• Email: <%= @user.email %>
7:
• Password: **********
8:

Thanks a lot in advance!

Your @user object is "nil". You need to make sure that you set @user, e.g. via a "before_filter".