what about Parent.objects.filter(~q) ?
On Thu, Apr 14, 2011 at 11:08, Gianluca Sforna <gia...@gmail.com> wrote:
> On Wed, Apr 13, 2011 at 3:43 PM, Brian Bouterse <bmbou...@gmail.com> wrote:
>> Could you include the output to highlight the differences?
>
> I've just created a simpler test case. I've a couple models like:
>
> class Parent(models.Model):
> name = models.CharField(max_length=200, db_index=True)
>
> class Child(models.Model):
> parent = models.ForeignKey('Parent')
> gender = models.CharField(max_length=1)
>
> Now let's filter them (I'm doing this in the ipython shell):
>
> In [11]: f1 = Parent.objects.filter(child__gender='f')
> In [12]: print f1.query
> SELECT "molserv_parent"."id", "molserv_parent"."name" FROM
> "molserv_parent" INNER JOIN "molserv_child" ON ("molserv_parent"."id"
> = "molserv_child"."parent_id") WHERE "molserv_child"."gender" = f
>
> Now the same with a Q object:
>
> In [13]: q = Q(child__gender='f')
> In [14]: f2 = Parent.objects.filter(q)
> In [15]: print f2.query
> SELECT "molserv_parent"."id", "molserv_parent"."name" FROM
> "molserv_parent" INNER JOIN "molserv_child" ON ("molserv_parent"."id"
> = "molserv_child"."parent_id") WHERE "molserv_child"."gender" = f
>
> So far, so good, they are the same. Now I'll replace filter with exclude:
>
> In [16]: f1 = Parent.objects.exclude(child__gender='f')
> In [17]: print f1.query
> SELECT "molserv_parent"."id", "molserv_parent"."name" FROM
> "molserv_parent" WHERE NOT ("molserv_parent"."id" IN (SELECT
> U1."parent_id" FROM "molserv_child" U1 WHERE (U1."gender" = f AND
> U1."parent_id" IS NOT NULL)))
>
> In [18]: f2 = Parent.objects.exclude(q)
> In [19]: print f2.query
> SELECT "molserv_parent"."id", "molserv_parent"."name" FROM
> "molserv_parent" INNER JOIN "molserv_child" ON ("molserv_parent"."id"
> = "molserv_child"."parent_id") WHERE NOT ("molserv_child"."gender" = f
> )
>
> So only the second (Q based) filter in this case works for me. For the
> records, this is with Django 1.2.5 in Fedora 14
>
> --
> Gianluca Sforna
>
> http://morefedora.blogspot.com
> http://identi.ca/giallu - http://twitter.com/giallu
>
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