#30463: Deprecation message generates error when query expression is used in
Meta.ordering
-------------------------------------+-------------------------------------
Reporter: Jannis | Owner: nobody
Type: | Status: new
Uncategorized |
Component: Database | Version: 2.2
layer (models, ORM) |
Severity: Normal | Keywords: ordering
Triage Stage: | Has patch: 0
Unreviewed |
Needs documentation: 0 | Needs tests: 0
Patch needs improvement: 0 | Easy pickings: 1
UI/UX: 0 |
-------------------------------------+-------------------------------------
Since updating to Django 2.2 our test suite fails because the newly
introduced deprecation warning which warns about Meta.ordering being
ignored from Django 3.1 onwards leads to errors when a query expression is
used.
Take a model definition like this as an example:
{{{
class Book
name = models.CharField(max_length=255)
class Meta:
ordering = [F('name',).asc()]
}}}
The error happens here:
{{{
File "django/django/db/models/sql/compiler.py", line 558, in as_sql
"', '".join(self._meta_ordering)
TypeError: sequence item 0: expected str instance, OrderBy found
}}}
A quick and dirty way around that problem is to join the string
representations of all the list items instead of concatenating them
directly:
{{{
warnings.warn(
"%s QuerySet won't use Meta.ordering in Django 3.1. "
"Add .order_by('%s') to retain the current query." % (
self.query.model.__name__,
"', '".join([str(f) for f in self._meta_ordering])
),
)
}}}
Unfortunately this doesn't generate real source code compatible with
`.order_by()` because the quotation marks are not correct.
Maybe someone else has a clean solution on how to fix this?
{{{
- Book QuerySet won't use Meta.ordering in Django 3.1. Add
.order_by('name', 'OrderBy(F(price), descending=False)') to retain the
current query.
- -
+ Book QuerySet won't use Meta.ordering in Django 3.1. Add
.order_by('name', OrderBy(F('price'), descending=False)) to retain the
current query.
}}}
A regression test is available here: https://github.com/jnns/django/tree
/meta-ordering-deprecation-warning
--
Ticket URL: <https://code.djangoproject.com/ticket/30463>
Django <https://code.djangoproject.com/>
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