Question

I have a model called “EmployeeRecord” and it has a field called username, There is another model called “Employee” with a field called username.

I want to create an association between the 2 models so when I do:

record = EmployeeRecord.find(1)
record.employee // returns Employee instance

I was thinking I’d just need to do this, but apparently it doesn’t work:

class EmployeeRecord < ActiveRecord::Base
    has_one :employee, :foreign_key: username
end

Assume I can’t add an employee_id field to EmployeeRecord. I scoured the Rails tutorials.. and recall wanting to know how to do this months ago.. but those dang Rails tutorials glided over this.. I remember.. it made me very very angry hehe

Any idea?

Answer 1

You’ll also need to specify the primary_key used for the association, or else it’s defaulted to “id”. Your statement actually says “Search for a field username in table employee that is equal to my id field“. What you actually want is “Search for a field username in table employee that is equal to my username field“

This should do the trick :

class EmployeeRecord < ActiveRecord::Base
    has_one :employee, :foreign_key => username, :primary_key => :username
end

But hey… Why don’t you use ids?