Ruby on Rails：未定义的方法`user'for＃

The code is below. User is the name in my database, but it is saying it is an undefined method when it should not be. It is just a string value in my database. I have looked at all the other posts about this error but their solutions did not work for me. (I used scaffold btw so I don't know if that affects anything)The code is below. User is the name in my datab