Basic has_one association nil:class error upon reflection

Rails upgrades Upgrade from 6.1 to 7.0
1

I’m working on an app written in 2018 on rails 6.0 and after upgrading to 7 I’ve been getting an error: "NoMethodError: undefined method `klass’ for nil:NilClass (NoMethodError)

At first i blamed Administrate because all the rest of my index views worked except one but then i opened rails console and pulled them all, (like an index query) which worked. but when getting attributes of the individual objects, the assoications with all but one class_name work. they all work under Rails 6 but not rails 7 or 8.

to be clear, here’s a snippit of my “JobPosting” class. the one in question

belongs_to :job_coach, class_name: ‘User’, optional: true

belongs_to :mentor, class_name: ‘Contact’, optional: true

now, the object has a valid job_coach_id and mentor_id but if i go

email_writer = JobPosting.find(3)

email_writer.mentor

i get

Contact:0x000000010e58ba60 … which is fine, but when i go

email_writer.job_coach

I get this error:

NoMethodError: undefined method `klass’ for nil:NilClass (NoMethodError)

    through_reflection.klass.\_reflect_on_association(n)

and I have no idea why. Other associations with of other classes are fine, it’s only the User class that can’t be referenced.

2

Hard to follow exactly what is going on here.

So in the Contact model do you have a has_one that goes to JobPosting?

class Contact < ApplicationRecord
  has_one :job_posting, foreign_key: :mentor_id
end

Or … perhaps does User have has_one :contact through: :job_postings?

Reason I ask is it’s hard to tell how you are getting a message about “through_reflection.klass._reflect_on_association”.