#33594: order_by("field1__-field2") yields inconsistent behavior
-------------------------------------+-------------------------------------
Reporter: Thomas Chaumeny | Owner: nobody
Type: Bug | Status: new
Component: Database layer | Version: 3.2
(models, ORM) |
Severity: Normal | Resolution:
Keywords: | Triage Stage:
| Unreviewed
Has patch: 0 | Needs documentation: 0
Needs tests: 0 | Patch needs improvement: 0
Easy pickings: 0 | UI/UX: 0
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Description changed by Thomas Chaumeny:
Old description:
> In our codebase, someone used `SomeModel.objects.order_by("foo__-
> created_at")` to order according to a foreign key's field and it was
> working (yielding the correct query with `DESC` order).
>
> However, after we added the following index on `SomeModel`:
>
> {{{
> class Meta:
> indexes = [
> models.Index(fields=["some_other_field", "created_at"]),
> ]
> }}}
>
> The same code `SomeModel.objects.order_by("foo__-created_at")` stopped
> working and started raising an error:
>
> {{{
> django.core.exceptions.FieldError: Cannot resolve keyword '-created_at'
> into field. Choices are: context, created_at, id, tag_readings,
> updated_at, user_id, warehouse_id
> }}}
>
> Shouldn't the pattern for ordering in a descending order with chaining be
> documented?
>
> According to
> https://github.com/django/django/blob/main/django/db/models/sql/compiler.py#L402-L403
> it should be `-foo__created_at`.
> Also, we should expect the wrong pattern to fail unconditionally.
New description:
In our codebase, someone used `SomeModel.objects.order_by("foo__-
created_at")` to order according to a foreign key's field and it was
working (yielding the correct query with `DESC` order).
However, after we added the following index on `SomeModel`:
{{{
class Meta:
indexes = [
models.Index(fields=["some_other_field", "-created_at"]),
]
}}}
The same code `SomeModel.objects.order_by("foo__-created_at")` stopped
working and started raising an error:
{{{
django.core.exceptions.FieldError: Cannot resolve keyword '-created_at'
into field. Choices are: context, created_at, id, tag_readings,
updated_at, user_id, warehouse_id
}}}
Shouldn't the pattern for ordering in a descending order with chaining be
documented?
According to
https://github.com/django/django/blob/main/django/db/models/sql/compiler.py#L402-L403
it should be `-foo__created_at`.
Also, we should expect the wrong pattern to fail unconditionally.
--
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Ticket URL: <https://code.djangoproject.com/ticket/33594#comment:1>
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