#33066: DateTimeField does not exclusively validate the date time format against
DATETIME_INPUT_FORMATS
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Reporter: Christian | Owner: nobody
Reksten-Monsen |
Type: Bug | Status: new
Component: Forms | Version: 3.2
Severity: Normal | Keywords: datetime iso8601
Triage Stage: | Has patch: 0
Unreviewed |
Needs documentation: 0 | Needs tests: 0
Patch needs improvement: 0 | Easy pickings: 0
UI/UX: 0 |
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According to the documentation on DATETIME_INPUT_FORMATS, the given list
of date time formats will be accepted when inputting data on a datetime
field. My assumption is that Django will ONLY accept formats from this
list (and also DATE_INPUT_FORMATS, as mentioned in the docs). Django will,
however, also accept ISO 8601 date inputs, even though these formats are
not present in DATETIME_INPUT_FORMATS. This is not mentioned in the docs.
This is because of [https://github.com/django/django/pull/11893 PR #11893]
for [https://code.djangoproject.com/ticket/11385 ticket 11385] which added
support for ISO 8601 date inputs. ISO 8601 matching is done in
DateTimeField and if there is a match, the BaseTemporalField to_python
method (which checks date time format against DATETIME_INPUT_FORMATS) is
never called.
This was confusing for me when unit testing a form field, a validation
error was not raised when giving a date format that was not present in
DATETIME_INPUT_FORMATS. Below test case replicates the issue.
Possible solutions:
* Add the date time format (with timezone format, which I believe was the
issue) to DATETIME_INPUT_FORMATS default. Python 2.7 and 3 strptime() do
support %z.
* Ignore it and update the docs that ISO 8601 date time formats will be
accepted, regardless of not being present in DATETIME_INPUT_FORMATS.
* Set a flag to strictly adhere DATETIME_INPUT_FORMATS or also allow ISO
8601 date time formats.
{{{#!python
from datetime import datetime
from django.core.exceptions import ValidationError
from <app_name>.settings import DATETIME_INPUT_FORMATS
from django.test import TestCase
class TestDateTimeField(TestCase):
def test_field_validation(self):
with self.settings(DATETIME_INPUT_FORMATS=['%d/%m/%Y %H:%M']):
field = DateTimeField(required=True)
self.assertIsInstance(field.clean("31/12/2021 14:30"),
datetime)
with self.assertRaises(ValidationError):
field.clean("2021-12-31 14:30")
}}}
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Ticket URL: <https://code.djangoproject.com/ticket/33066>
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