fix: create new record from belongs_to associations

[Paul-Bob]

Description

via_resource_id: resource.model.to_param when resource.model is not a persistent yet to_param will return nil and that's fine. But in case you use prefix_id or some other ID manipulation it will break if the attributes used on the manipulation are blank.

Fixes #2045

Checklist:

• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• I have added tests that prove my fix is effective or that my feature works

Screenshots

Manual review steps

1. Step 1
2. Step 2

Manual reviewer: please leave a comment with output from the test if that's the case.