#30854: FilteredRelation on ManyToOne generates wrong result
-------------------------------------+-------------------------------------
Reporter: | Owner: nobody
mortezaPRK |
Type: Bug | Status: new
Component: Database | Version: 2.2
layer (models, ORM) | Keywords: FilteredRelation
Severity: Normal | annotate
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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When using FilteredRelation multiple times in single query, results are
wrong.
consider following example (with Django 2.2.6):
The models are:
{{{#!python
from django.db import models
class UserType(models.Model):
pass
class Commodity(models.Model):
pass
class CommodityCount(models.Model):
commodity = models.ForeignKey(Commodity, on_delete=models.CASCADE)
user_type = models.ForeignKey(UserType, on_delete=models.CASCADE)
small_box = models.IntegerField(default=0)
class Meta:
unique_together = ('commodity', 'user_type')
class CommodityDiscount(models.Model):
commodity = models.ForeignKey(Commodity, on_delete=models.CASCADE)
user_type = models.ForeignKey(UserType, on_delete=models.CASCADE)
small_box = models.IntegerField(default=0)
class Meta:
unique_together = ('commodity', 'user_type')
}}}
following query is what I want:
{{{#!python
query = Commodity.objects.annotate(
cnt=FilteredRelation('commoditycount',
condition=Q(commoditycount__user_type_id=1)),
dst=FilteredRelation('commoditydiscount',
condition=Q(commoditydiscount__user_type_id=1))
).filter(
cnt__isnull=False,
dst__isnull=False
).select_related('cnt','dst')
}}}
resulting query is ok:
{{{#!sql
SELECT
"ma_commodity"."id",
cnt."id",
cnt."commodity_id",
cnt."user_type_id",
cnt."small_box",
dst."id",
dst."commodity_id",
dst."user_type_id",
dst."small_box"
FROM
"ma_commodity"
INNER JOIN "ma_commoditycount" cnt ON (
"ma_commodity"."id" = cnt."commodity_id"
AND (cnt."user_type_id" = 1)
)
INNER JOIN "ma_commoditydiscount" dst ON (
"ma_commodity"."id" = dst."commodity_id"
AND (dst."user_type_id" = 1)
)
WHERE
(
cnt."id" IS NOT NULL
AND dst."id" IS NOT NULL
)
}}}
but results are not ok:
{{{#!python
first_item = query.first()
print(dir(first_item))
>>> [ ... '_state', 'check', 'clean', 'clean_fields',
'commoditycount_set', 'commoditydiscount_set',
'date_error_message', 'delete', 'dst', 'from_db', 'full_clean',
'get_deferred_fields', 'id', 'objects',
'pk', 'prepare_database_save', 'refresh_from_db', 'save', 'save_base',
'serializable_value', 'unique_error_message', 'validate_unique'
]
}}}
as you can see, there is dst, but no cnt.
if I remove dst and its related FilteredRelation, cnt re appear.
--
Ticket URL: <https://code.djangoproject.com/ticket/30854>
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