#35339: Ordering and filtering a Postgres ArrayAgg with parameters inverts SQL
param order
-------------------------------------+-------------------------------------
Reporter: Chris M | Owner: Chris M
Type: Bug | Status: closed
Component: Database layer | Version: dev
(models, ORM) |
Severity: Normal | Resolution: fixed
Keywords: postgres arrayagg | Triage Stage: Ready for
ordering | checkin
Has patch: 1 | Needs documentation: 0
Needs tests: 0 | Patch needs improvement: 0
Easy pickings: 0 | UI/UX: 0
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Comment (by Simon Charette):
Hello Chris, glad to hear you're interested in moving this forward! We
should definitely create a new ticket for that.
I'd suggest targeting `StringAgg(Aggregate)` and default to using
`STRING_AGG` (Postgres, SQLite), `GROUP_CONCAT` as fallback on MySQL, and
`LIST_AGG WITHIN GROUP (ORDER BY)` on Oracle.
As for whether `StringAgg` should live in `models.aggregate` (or only in
tests at first) I think it could even if that means documenting it.
Another potential candidate that could be added is `JSONArrayAgg` but I
think we should focus on a single one for this first ticket.
A few things I believe we should focus on along the way
1. We should make the argument `Aggregate(order_by)` instead of `ordering`
to be consistent with `Window`
2. Just like we do with `allow_distinct` we should use a `allow_order_by`
attribute for aggregates that support this feature
3. We should make `OrderableAggMixin` a shim that sets
`allow_order_by=True`, redirect `__init__(ordering)` to `order_by`, and
emit a deprecation warning when doing so to allow a proper transition for
`contrib.postgres.ArrayAgg` and friends
4. We should reuse `OrderByList` as much as possible
If that can be of any help
[https://github.com/charettes/django/commits/ticket-35339-generic-order-
by-aggregate/ I hacked a bit on it a few days ago to make sure I didn't
send through a rabbit hole] by requesting these
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Ticket URL: <https://code.djangoproject.com/ticket/35339#comment:13>
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