Validation failed Class must exist

Question

I have been (hours) trouble with associations in Rails. I found a lot of similar problems, but I couldn\'t apply for my case:

City\'s class:

class Ci         


        

Answer 1

This comes a bit late but this is how to turn off this by default in rails 5:

config/initializers/new_framework_defaults.rb

Rails.application.config.active_record.belongs_to_required_by_default = false

In case you don't want to add optional: true to all your belongs_to.

I hope this helps!