Undefined method for a belongs_to association

Question

My code:

class User < ActiveRecord::Base
    belongs_to :university
end

class University < ActiveRecord::Base
  has_many :users, dependent: :destroy
end

and my model User has a university_id attribute.

If I do University.find(1).users I get the list of users, but if I do User.find(1).university (and I checked that university_id is not nil here) I get:

NoMethodError: undefined method `university' for #<User:0x00000003859fc8>
from /home/mari/.rvm/gems/ruby-1.9.2-p290/gems/activemodel-3.0.10/lib/active_model/attribute_methods.rb :392:in `method_missing'
from /home/mari/.rvm/gems/ruby-1.9.2-p290/gems/activerecord-3.0.10/lib/active_record/attribute_methods. rb:46:in `method_missing'
from (irb):14
from /home/mari/.rvm/gems/ruby-1.9.2-p290/gems/railties-3.0.10/lib/rails/commands/console.rb:44:in`start'
from /home/mari/.rvm/gems/ruby-1.9.2-p290/gems/railties-3.0.10/lib/rails/commands/console.rb:8:in start'
from /home/mari/.rvm/gems/ruby-1.9.2-p290/gems/railties-3.0.10/lib/rails/commands.rb:23:in
`<top (required)>'
from script/rails:6:in `require'
from script/rails:6:in `<main>'

What am I doing wrong? I have another models and they are working just fine. Any suggestions? Thanks in advance

That's weird, what happens when you type **User.new.university** ? — Maurício Linhares, Jun 04 '12 at 04:45
Column in database exists? Usually this is the cause of this error. — Eraden, Jun 04 '12 at 06:40
It exists, as I mentioned, I check that the column is not nil before I call it and it still throws that error — marimaf, Jun 04 '12 at 06:55
isn't it typo there "has_many :users, dependent: :destroy" should be "has_many :users, :dependent => :destroy: — Amol Pujari, Jun 04 '12 at 07:13
@AmolPujari: That's new-style hash syntax and perfectly valid (when using Ruby 1.9) — Holger Just, Jun 04 '12 at 07:35
ohh :) I must know reason behind this, else at 1st glance I think I find it weird — Amol Pujari, Jun 04 '12 at 08:13

score 8 · Accepted Answer · answered Jun 04 '12 at 05:45

8

I still can't comment so I'll burn an answer:

Somehow the belongs_to :university in the User model isn't being recognized. When testing, are you certain that the User model has been saved and is in the right place and that the server or console has been refreshed? Most commonly, in my experience, when I'm meddling with models, I have to refresh my server and console often to get clean results.

answered Jun 04 '12 at 05:45

DavidMann10k

553
1
4
12

Along those lines, are there other User classes out there in a gem or library you're using? Is your User class in the proper file location (/app/models/user.rb)? Looks like a load-order problem or file inclusion problem to me - your code is fine from what you've posted. – Irongaze.com Jun 04 '12 at 13:10
2

So it happens that Lambda Red was right. Today I was starting to work again and the problem was solved! I guess a reboot of the console (or server) did the trick. I feel stupid now haha. I just can't get my mind around it, why one "side" was working and the other one wasnt... anyhow.. its working now. Thanks! – marimaf Jun 05 '12 at 01:15
1

Perfect! `reload!` after every model change is a good habit to make – Alexander Suraphel Mar 02 '14 at 15:35

score 1 · Answer 2 · answered May 20 '13 at 06:47

1

Try

User.where("id =?", 1).first.university

answered May 20 '13 at 06:47

Michael Moulsdale

1,488
13
34

Undefined method for a belongs_to association

2 Answers2