django.db.models.fields.related_descriptors.RelatedObjectDoesNotExist by testing django form

Question

I have the following model:

class Damage(models.Model):
    kind = models.ForeignKey(Kind, on_delete=models.PROTECT)
    region = models.ForeignKey(Region, on_delete=models.PROTECT)

    def clean(self):
        if self.region not in self.kind.regions.all():
            raise ValidationError('not possible')

and the corresponding form:

class DamageForm(forms.ModelForm):
    class Meta:
        model = Damage
        fields = ['kind', 'region']

when I run the following tests, I always get the django.db.models.fields.related_descriptors.RelatedObjectDoesNotExist: Damage has no region failure.

def test_empty_input(self):
    data = {
        'kind': None,
        'region': None,
    }
    form = DamageForm(data)
    self.assertFalse(form.is_valid())

def test_invalid_input(self):
    data = {
        'kind': self.test_kind,
        'region': self.test_region,
    }
    form = DamageForm(data)
    self.assertFalse(form.is_valid())

Answer 1

Check that the region_id and self.kind_id are not None before trying to access self.region or self.kind in your clean method.

def clean(self):
    if self.region_id is not None self.kind_id is not None and self.region not in self.kind.regions.all():
        raise ValidationError('not possible')