#31535: Calling annotate with a case statement that references a recursive many
to
many relationship creates duplicates.
-------------------------------------+-------------------------------------
Reporter: David Cooke | Owner: nobody
Type: Bug | Status: closed
Component: Database layer | Version: master
(models, ORM) |
Severity: Normal | Resolution: invalid
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 felixxm):
* status: new => closed
* resolution: => invalid
Comment:
This is documented behavior (see the warning in the
[https://docs.djangoproject.com/en/dev/ref/models/querysets/#values
QuerySet.values() docs]):
Because `ManyToManyField` attributes and reverse relations can have
multiple related rows, including these can have a multiplier effect on the
size of your result set. This will be especially pronounced if you include
multiple such fields in your `values()` query, in which case all possible
combinations will be returned.
You can use `Subquery()` or `.distinct(...)` to avoid duplicate.
--
Ticket URL: <https://code.djangoproject.com/ticket/31535#comment:2>
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