has_many with different foreign key


I am new to rails and am trying to get my associations straight. I have a User model and a Property model. I'd like to track who has updated a property record, so I added an integer field to the properties table called updated_by. Then I made the following changes:

In the User model:   has_many :properties

In the Property model:   belongs_to :user, :class_name => "User", :foreign_key => 'updated_by'

Here's what I see inside of the rails console:

prop = Property.first

=> #<Property id: 1, name: "Main Street Center", ..., updated_by: nil>

usr = User.first

=> #<User id: 1, login: "sshartles", name: "Sam Shartles", ... >

prop.user = usr

=> #<User id: 1, login: "sshartles", name: "Sam Shartles", ... >


=> 1


NoMethodError: undefined method `name' for 1:Fixnum         from (irb):5

I'm not sure what I've done, but I think it's something simple. Any help would be massively appreciated.