The required validation which comes from 'belongs_to' in Rails 5 doesn't work

[kyamaguchi]

Tested on the sample app.
https://github.com/kyamaguchi/required_validation_from_belongs_to

Rails 5 requires relation with belongs_to by default.
rails/rails#18233

But it doesn't work after adding 'audited'.

$ rails console

> User.new(name: 'Foo').valid?
 => true

Before adding 'audited' gem,

> Company.create(name: 'Test')
> User.new(name: 'Foo').valid?
 => false
> User.new(name: 'Foo', company: Company.first).valid?
 => true

I tested on the different versions of Rails on branches on the sample app and it works fine with rails 5.1.
It doesn't work with rails '>= 5.0.0, ~> 5.0.0'.

---

Simple solutions are

1. Upgrading Rails to 5.1

2. Add required: true option

class User < ApplicationRecord
  belongs_to :company, required: false

[brendon]

From memory this was to do with ActiveRecord being initialised way before the Rails Default initialiser file is run (due to a particular gem touching it early on). The solution is to configure it earlier in the boot process, or as you say, just keep on upgrading through to Rails 5.1.