#9596: Comparing a DateTimeField to a date is too hard
-------------------------------------+-------------------------------------
Reporter: django@… | Owner: nobody
Type: New feature | Status: new
Component: Database layer | Version: SVN
(models, ORM) | Resolution:
Severity: Normal | Triage Stage: Accepted
Keywords: lookup_type date | Needs documentation: 0
datetimefield compare comparison | Patch needs improvement: 1
query_term field lookup | UI/UX: 0
Has patch: 1 |
Needs tests: 0 |
Easy pickings: 0 |
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Changes (by aaugustin):
* stage: Design decision needed => Accepted
Comment:
This ticket is in DDN because the current technique fails if the `__date`
lookup is used on a `DateField`.
There is exactly the same problem with the `year` lookup; its
implementation depends on the field it's applied to:
{{{
# django/db/models/fields/__init__.py
elif lookup_type == 'year':
if self.get_internal_type() == 'DateField':
return
connection.ops.year_lookup_bounds_for_date_field(value)
else:
return connection.ops.year_lookup_bounds(value)
}}}
The implementation of `year_lookup_bounds` and
`year_lookup_bounds_for_date_field` is database dependent. This allows
setting the upper bound to `YYYY-12-31` instead of `YYYY-12-31
23:59:59.999999` for `DateField`s under Oracle.
I think we could mirror this solution for the `__date` lookup. This means
implementing `connection.ops.date_lookup_bounds(value)`
`connection.ops.date_lookup_bounds_for_date_field(value)` (in a backend
dependent fashion if necessary).
It would be even better to convert the lookup to an exact match for
`DateField`, but I don't believe that's doable with the current
implementation.
Note that the tests in the patch need to be rewritten as unittests.
--
Ticket URL: <https://code.djangoproject.com/ticket/9596#comment:23>
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