Re: multiple filters on the same (reversed) foreignkey leads to multiple join

That is expected behavior. The filter should be read as "there is a child with flag1 equals true". Another example where this is the desired behavior would be Band.objects.filter(member__name='John', member__name='Paul', member__name='George', member__name='Ringo') . In this case you are looking for a band with at least four different members.

On Sep 6, 2011, at 5:09 PM, dvd wrote:

> A clean project/app in django 1.3 with just two models
>
> from django.db import models
>
> class Base(models.Model):
> pass
>
> class Child(models.Model):
> base = models.ForeignKey(Base)
> flag1 = models.BooleanField()
> flag2 = models.BooleanField()
>
> A Queryset with a single use of `.filter` works as expected:
>>>> qs = Base.objects.filter(child__flag1=True)
>>>> print qs.query
> SELECT "t0_base"."id"
> FROM "t0_base" INNER JOIN "t0_child"
> ON ("t0_base"."id" = "t0_child"."base_id")
> WHERE "t0_child"."flag1" = True
>
> but if I start to add additional filters...
>>>> qs = qs.filter(child__flag2=True)
>>>> print qs.query
> SELECT "t0_base"."id"
> FROM "t0_base" INNER JOIN "t0_child"
> ON ("t0_base"."id" = "t0_child"."base_id")
> INNER JOIN "t0_child" T3
> ON ("t0_base"."id" = T3."base_id")
> WHERE ("t0_child"."flag1" = True AND T3."flag2" = True )
>
>>>> qs = qs.filter(child__flag1=False)
>>>> print qs.query
> SELECT "t0_base"."id"
> FROM "t0_base" INNER JOIN "t0_child"
> ON ("t0_base"."id" = "t0_child"."base_id")
> INNER JOIN "t0_child" T3
> ON ("t0_base"."id" = T3."base_id")
> INNER JOIN "t0_child" T4
> ON ("t0_base"."id" = T4."base_id")
> WHERE ("t0_child"."flag1" = True AND T3."flag2" = True AND
> T4."flag1" = False )
>
> I don't think that this is the expected behavior, should I open a new
> bug?
>
> david
>
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Peter of the Norse
RahmCoff@Radio1190.org

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