#31469: Custom lookup ignored inside built-in aggregation
-------------------------------------+-------------------------------------
Reporter: Oliver | Owner: nobody
Ford |
Type: Bug | Status: new
Component: Database | Version: 3.0
layer (models, ORM) | Keywords: custom
Severity: Normal | lookup,aggregation
Triage Stage: | Has patch: 0
Unreviewed |
Needs documentation: 0 | Needs tests: 0
Patch needs improvement: 0 | Easy pickings: 0
UI/UX: 0 |
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With a '[[https://docs.djangoproject.com/en/3.0/howto/custom-
lookups/|custom lookup]]' such as:
{{{
@JSONField.register_lookup
class JsonbArrayLength(models.Transform):
output_field = models.IntegerField()
lookup_name = "arraylen"
function = "JSONB_ARRAY_LENGTH"
}}}
Using it as `qs.annotate(num_items=models.Sum("jsonfield__arraylen"))`
results in the query fragment:
{{{
SELECT SUM("model"."jsonfield") AS "num_items"
}}}
i.e. the `arraylen` lookup is ignored/not done.
`qs.values("jsonfield__arraylen")` works as expected.
Modifying it to `models.Sum(JsonbArrayLength("jsonfield"))` gives the
desired result.
--
Ticket URL: <https://code.djangoproject.com/ticket/31469>
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