#32584: OrderBy.as_sql() overwrites template
-------------------------------------+-------------------------------------
Reporter: Tim | Owner: nobody
Nyborg |
Type: | Status: new
Uncategorized |
Component: Database | Version: 3.1
layer (models, ORM) | Keywords: order_by,
Severity: Normal | nulls_first
Triage Stage: | Has patch: 1
Unreviewed |
Needs documentation: 0 | Needs tests: 0
Patch needs improvement: 0 | Easy pickings: 0
UI/UX: 0 |
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A change in 3.1 has caused OrderBy.as_sql() in
django.db.models.expressions to ignore sql templates provided by db
backends when nulls_first or nulls_last is set:
{{{
def as_sql(self, compiler, connection, template=None, **extra_context):
template = template or self.template
if connection.features.supports_order_by_nulls_modifier:
if self.nulls_last:
template = '%s NULLS LAST' % template
elif self.nulls_first:
template = '%s NULLS FIRST' % template
else:
if self.nulls_last and not (
self.descending and
connection.features.order_by_nulls_first
):
template = '%%(expression)s IS NULL, %s' % template
elif self.nulls_first and not (
not self.descending and
connection.features.order_by_nulls_first
):
template = '%%(expression)s IS NOT NULL, %s' % template
}}}
Note that template is always overwritten if nulls_first == True. In 3.0,
the function first tested for template == None.
This causes trouble for the MSSQL 3rd party driver, which provides its own
order by functionality:
https://github.com/microsoft/mssql-django/issues/19
The following change (simply testing for template) fixed the issue for me
(forked off 3.1 as I'm on py 3.7)
https://github.com/timnyborg/django/commit/fd41b39ade8d37138951223eba7f2e3fb66d0d1c
--
Ticket URL: <https://code.djangoproject.com/ticket/32584>
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