#36048: CompositePrimaryKey lookup guards raise NotSupportedError instead of a
more
appropriate exception
-------------------------------------+-------------------------------------
Reporter: Jacob | Owner: Jacob Walls
Walls |
Type: Bug | Status: assigned
Component: Database | Version: dev
layer (models, ORM) |
Severity: Release | Keywords:
blocker |
Triage Stage: | Has patch: 0
Unreviewed |
Needs documentation: 0 | Needs tests: 0
Patch needs improvement: 0 | Easy pickings: 0
UI/UX: 0 |
-------------------------------------+-------------------------------------
Django mostly(*) raises `NotSupportedError` as documented in
[https://peps.python.org/pep-0249/#notsupportederror PEP 249], to signify
that a database feature is missing. Instead, some of the
`CompositePrimaryKey` sanity checks raise regardless of db feature flags.
Given that, I'm suggesting that `ValueError` etc. would be more
appropriate in these two locations:
-
[https://github.com/django/django/blob/8d9901c961bf9d5cfa6bddddbbcebfbf487a5125/django/db/models/fields/related_lookups.py#L120
RelatedLookupMixin.as_sql]
-
[https://github.com/django/django/blob/8d9901c961bf9d5cfa6bddddbbcebfbf487a5125/django/db/models/aggregates.py#L185
Count.resolve_expression]
Our
[https://github.com/django/django/blob/8d9901c961bf9d5cfa6bddddbbcebfbf487a5125/django/db/backends/base/operations.py#L663
guidance] says "specific backends":
> This is used on specific backends to rule out known expressions that
have problematic or nonexistent implementations. If the expression has a
known problem, the backend should raise NotSupportedError.
Essentially the inverse of #28665. Marking as a release blocker for now to
ensure we consider this before finalizing the feature.
----
*: The handful of places we're raising `NotSupportedError` regardless of
db feature flags include:
- Query.check_filterable
- QuerySet._not_support_combined_queries
- QuerySet.get
- Field.slice_expression
- ResolvedOuterRef.resolve_expression
I'm not suggesting to do anything about those at the moment.
--
Ticket URL: <https://code.djangoproject.com/ticket/36048>
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