IntegrityError null value in column "prefill_plugin" of relation "forms_formvariable" violates not-null constraint

[LaurensBurger]

Product versie / Product version

2.5.x (new form builder)

Omschrijf het probleem / Describe the bug

when copying a form that contains a textfield a 500 occurs.
the cause seems to be:

  "prefill": {
    "plugin": null,
    "attribute": null,
    "identifierRole": "main"
  },

which is included in new textfields. removing this part from the json fixes the issue in the form builder

Tasks

• Do not allow null in TS types Disallow null values for prefill plugin or attribute types#44
• Fix formio builder to set empty strings as default instead of null Fix default/empty values for component prefill configuration formio-builder#127
• Fix backend with data migration to nuke the nulls and change them into empty string

[LaurensBurger]

#3467

[sergei-maertens]

I was a bit baffled why this only manifests during copying (and likely import) of a form and not during the normal form editing, but I could find out that the JS actually cleans up these null values when creating the variable, which the backend code does not appear to do:

open-forms/src/openforms/js/components/admin/form_design/variables/utils.js

Line 46 in ac70173

prefillPlugin: component.prefill?.plugin || '',

While the backend does:

open-forms/src/openforms/forms/models/form_variable.py

Line 67 in ac70173

prefill_plugin=glom(

So the backend patch will make this a bit more robust and also add a data/import fix to convert component configurations (again).