Invalid input for UUIDField with ModelMultipleChoiceField throws ValueError, not ValidationError

[Daniel Hahler]

I have added a test in ​https://github.com/django/django/pull/7180.

This test shows that an invalid value for a UUIDField will bubble up as
ValueError. The problem here seems to be that get_prep_value just
passes through the (invalid) string.

Only when the queryset is evaluated just below via the following code,
the ValueError from UUIDField.get_db_prep_value is raised and bubbles
up:

self.queryset.filter(**{'%s__in' % key: value})
pks = set(force_text(getattr(o, key)) for o in qs)

Explicitly evaluating the queryset above already would fix it, but that
would get done for every selected value then.

Needs UUIDField to be fixed for this, e.g. raising the ValueError
from get_prep_value already?
In this case other fields would need the same fix probably (from what I
have seen while skimming the code).

[Tim Graham]

Something like the attached might be appropriate.

[Tim Graham]

​PR

[GitHub <noreply@…>]

In 2f9861d8:

Fixed #27148 -- Fixed ModelMultipleChoiceField crash with invalid UUID.

[Tim Graham <timograham@…>]

In d264131:

Refs #27148 -- Fixed UUIDField.to_python(None) crash.

Regression in 2f9861d823620da7ecb291a8f005f53da12b1e89.

[Tim Graham <timograham@…>]

In 4101b57:

[1.11.x] Refs #27148 -- Fixed UUIDField.to_python(None) crash.

Regression in 2f9861d823620da7ecb291a8f005f53da12b1e89.

Backport of d26413113c1a5c95218fe4e43a684a2fe1ad1bff from master