#34594: KT doesn’t work across foreign keys
-------------------------------------+-------------------------------------
Reporter: Roman Odaisky | Owner: nobody
Type: New feature | Status: closed
Component: Database layer | Version: 4.2
(models, ORM) |
Severity: Normal | Resolution: wontfix
Keywords: | Triage Stage:
| Unreviewed
Has patch: 0 | Needs documentation: 0
Needs tests: 0 | Patch needs improvement: 0
Easy pickings: 0 | UI/UX: 0
-------------------------------------+-------------------------------------
Changes (by Mariusz Felisiak):
* status: new => closed
* type: Bug => New feature
* resolution: => wontfix
Comment:
> The problem is in the SQL that KT generates: `("parent"."id" #>>
ARRAY['data','some_string']) AS "x"`, which, it seems, is the result of
KeyTextTransform.from_lookup taking all the double-underscore-separated
parts of the argument of KT to mean JSON lookups and not other possible
lookups such as foreign keys.
Thanks for the report, however, it works exactly as
[https://docs.djangoproject.com/en/stable/topics/db/queries/#django.db.models.fields.json.KT
documented] ''"You can use the double underscore notation in `lookup` to
chain dictionary key and index transforms."'', so it's not a bug but a new
feature request. As far as I'm aware we don't want to complicate it, and
you can annotate nested `JSONField` to make it work, e.g.
{{{
Child.objects.annotate(data=F("parent__data"), x=KT("data__some_string"))
}}}
You can start a discussion on DevelopersMailingList if you don't agree.
--
Ticket URL: <https://code.djangoproject.com/ticket/34594#comment:1>
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