#20205: PositiveIntegerfield does not handle empty values well
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Reporter: anonymous | Owner: AmiZya
Type: Bug | Status: assigned
Component: Database layer | Version: master
(models, ORM) | Resolution:
Severity: Normal | Triage Stage: Accepted
Keywords: | Needs documentation: 0
Has patch: 1 | Patch needs improvement: 1
Needs tests: 0 | UI/UX: 0
Easy pickings: 0 |
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Comment (by Adam Easterling <easterling.adam@…>):
After thinking about this issue at some length myself, I agree with
loic84: The real problem is that Model doesn't call a field's clean method
in the case that the value is "empty." That logic doesn't seem to belong
to the Model.
To me, it seems that this logic should be moved to the field class, so
each field could decide what's a valid "empty value" and what isn't.
Furthermore, there's a comment near the aformentioned Model logic that
says, "Skip validation for empty fields with blank=True. The developer is
responsible for making sure they have a valid value." This is odd to me --
the developer is responsible for making sure that fields have a valid
value, but where would that appropriately be done? You can't add a
validator to the field, as clean() isn't run for that field. Any remaining
solutions seem rather hacky.
My own solution was to just override all number fields and change how they
work, but I'm not super proud of it. Here's an example for Integers:
{{{
class FixedIntegerMixin(object):
'''
If you attempt to save an int field with a blank string, Django
doesn't
convert that to a None object, which is what the db expects.
Also, if the value is "blank" according to Django (see EMPTY_VALUES
found
at django.core.validators) it won't call to_python for that field (see
full_clean at django.db.models.base).
This means that we have to override get_prep_value itself.
'''
def get_prep_value(self, value):
if value is None:
return None
if value == "":
return None
return int(value)
class IntegerField(FixedIntegerMixin, IntegerField_django):
pass
class SmallIntegerField(FixedIntegerMixin, SmallIntegerField_django):
pass
class PositiveIntegerField(FixedIntegerMixin,
PositiveIntegerField_django):
pass
class PositiveSmallIntegerField(FixedIntegerMixin,
PositiveSmallIntegerField_django):
pass
}}}
--
Ticket URL: <https://code.djangoproject.com/ticket/20205#comment:19>
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