Fixes #14482 - Fix validation error when primary IP is moved

[DanSheps]

Fixes: #14482

When an Primary IP address is moved, it should result in a validation error. However, it does not normally due to the fact that the clean() method on the model returns with the field assigned_object instead of interface, vminterface, or fhrpgroup. When the _post_clean() method tries to resolve the fields, it will fail because the form does not contain assigned_object as a field and returns a ValueError.

This will correctly map the assigned_object field to the correct field, however we should maybe look at instead providing a method to have assigned_object (or similar GFK fields) as proper form fields in the future, perhaps using a custom form field.

[jeremystretch]

This isn't a tenable approach to fixing the validation. We need to adjust the logic under the model form's clean() method to ensure it's catching the error and raising a ValidationError against the appropriate field before the model's full_clean() method is called.

[DanSheps]

We need to adjust the logic under the model form's clean() method to ensure it's catching the error and raising a ValidationError against the appropriate field before the model's full_clean() method is called.

This isn't an option.

The "clean" flow is:

form.save() -> form.full_clean() -> form._clean_fields()
                                                       form._clean_form() -> form.clean()
                                                       form._post_clean() -> model.full_clean()

the form.clean_form() catches the validation error and adds it to the stack, however the post_clean calls the model clean regardless of whether there is already an error on the stack.

The error stack looks like this:

{
    "assigned_object": "Cannot reassign IP address while it is designated as the primary IP for the parent object",
    "vminterface": "Cannot reassign IP address while it is designated as the primary IP for the parent object"
}

The only way to remove this problem seems to be to also remove the ErrorDict from the model clean() and just throw a straight string validation error (pushing this change now).

I think realistically we need to re-investigate GFK's and see if there isn't a way to:

• Create a fieldgroup called "assigned_object" (or whatever the GFK name is)
• Create a select field called "assigned_object_type" (or whatever the GFK type field name is) that is populated with the types available for selection
• Create a select field called "assigned_object_id" (or whatever the GFK id field name is) that is populated with the objects available for selection based on the type selected
• Modify add_error to also match on the assigned_object fieldgroup

This obviously wouldn't be do-able in this FR but something to think about.

[jeremystretch]

Why is this needed? Decoupling the ValidationError from a specific field under the model's clean() seems sufficient to address the bug.

[DanSheps]

It likely isn't needed, but it was an attempt to maintain the field highlighting. However you are correct that it likely isn't needed with just the decoupling.

[jeremystretch]

Thanks @DanSheps!