#19073: strange behaviuor of select_related
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Reporter: anonymous | Owner: nobody
Type: Bug | Status: new
Component: Database layer (models, ORM) | Version: 1.4
Severity: Normal | Keywords:
Triage Stage: Unreviewed | Has patch: 0
Easy pickings: 0 | UI/UX: 0
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Sometimes Django uses inner join instead of left outer join in queries
with select_related. This breaks queries with nullable OneToOne fields.
Here's the example
models:
{{{
class A(models.Model):
pass
class B(models.Model):
pass
class C(models.Model):
b = models.OneToOneField(B)
a = models.ForeignKey(A)
class D(models.Model):
b = models.OneToOneField(B, null=True)
}}}
code
{{{
D.objects.all()
[<D: D object>, <D: D object>, <D: D object>] #ok
>>> D.objects.select_related('b').all()
[<D: D object>, <D: D object>, <D: D object>] #ok
>>> D.objects.select_related('b', 'b__c').all()
[<D: D object>, <D: D object>, <D: D object>] #ok
>>> D.objects.select_related('b', 'b__c__a').all()
[] #WRONG! empty result
>>> print D.objects.select_related('b', 'b__c__a').all().query
SELECT "app1_d"."id", "app1_d"."b_id", "app1_b"."id", "app1_c"."id",
"app1_c"."b_id", "app1_c"."a_id", "app1_a"."id" FROM "app1_d" LEFT OUTER
JOIN "app1_b" ON ("app1_d"."b_id" = "app1_b"."id") LEFT OUTER JOIN
"app1_c" ON ("app1_b"."id" = "app1_c"."b_id") INNER JOIN "app1_a" ON
("app1_c"."a_id" = "app1_a"."id")
}}}
'''INNER JOIN "app1_a"''' should be '''LEFT OUTER JOIN "app1_a"''' imo
--
Ticket URL: <https://code.djangoproject.com/ticket/19073>
Django <https://code.djangoproject.com/>
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