#35374: UniqueConstraint (and potentially other constraints) validation is not
run
when using a form generated from `inlineformset_factory`
--------------------------------------+------------------------
Reporter: David Hang | Owner: nobody
Type: Bug | Status: new
Component: Forms | Version: 4.1
Severity: Normal | Keywords:
Triage Stage: Unreviewed | Has patch: 0
Needs documentation: 0 | Needs tests: 0
Patch needs improvement: 0 | Easy pickings: 0
UI/UX: 0 |
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Due to how refactors in Django 4+ on how the unique validations are run
for models and forms, an edge case has occured where in an inline form,
`UniqueConstraint` checks which were previously run are now being skipped
over and not returning validation errors, which then causing database
integrity errors when the form is attempted to be saved.
Reproducible example:
{{{
from django.forms import inlineformset_factory
from django import forms
from django.db import models
class Farm(models.Model):
name = models.CharField(max_length=255)
class Apple(models.Model):
name = models.CharField(max_length=255)
farm = models.ForeignKey(Farm, on_delete=models.CASCADE)
class Meta:
constraints = [
models.UniqueConstraint(fields=["name", "farm"],
name="unique_apple")
]
class AppleForm(forms.ModelForm):
class Meta:
model = Apple
fields = ["name", "farm"]
big_farm = Farm.objects.create(name="Big Farm")
best_apple = Apple.objects.create(name="Best Apple", farm=big_farm)
AppleFormSet = inlineformset_factory(Farm, Apple, AppleForm)
data = {
"apple_set-TOTAL_FORMS": "2",
"apple_set-INITIAL_FORMS": "0",
"apple_set-0-name": "Best Apple",
"apple_set-0-farm": big_farm.pk,
}
formset = AppleFormSet(data, instance=big_farm)
print(formset.is_valid())
print(formset.errors)
formset.save()
}}}
{{{
IntegrityError: duplicate key value violates unique constraint
"unique_apple"
DETAIL: Key (name, farm_id)=(Best Apple, 3) already exists.
}}}
In normal forms, and formsets, the validation does run correctly. This
issue caused by
https://github.com/django/django/blob/42bc81b1b6471c4fe364bc32b9dec180908e577e/django/forms/models.py#L486
{{{
# Foreign Keys being used to represent inline relationships
# are excluded from basic field value validation. This is for two
# reasons: firstly, the value may not be supplied (#12507; the
# case of providing new values to the admin); secondly the
# object being referred to may not yet fully exist (#12749).
# However, these fields *must* be included in uniqueness checks,
# so this can't be part of _get_validation_exclusions().
for name, field in self.fields.items():
if isinstance(field, InlineForeignKeyField):
exclude.add(name)
}}}
--
Ticket URL: <https://code.djangoproject.com/ticket/35374>
Django <https://code.djangoproject.com/>
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