#10742: ModelAdmin.list_select_related needs three-valued logic to support
custom
select_related() calls
----------------------------------+-----------------------------------------
Reporter: mrts | Owner: nobody
Status: new | Milestone: 1.1
Component: django.contrib.admin | Version: SVN
Keywords: | Stage: Unreviewed
Has_patch: 1 |
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If any of the related fields in a model is nullable, e.g.
{{{
class C(Base):
a = models.ForeignKey(A, blank=True, null=True)
b = models.ForeignKey(B)
is_published = models.BooleanField()
}}}
, `select_related()` does not pull them in by default (see
http://docs.djangoproject.com/en/dev/ref/models/querysets/#select-
related).
Forcing it explicitly as follows
{{{
class CAdmin(admin.ModelAdmin):
list_display = ('name', 'a', 'b', 'is_published')
list_select_related = None
def queryset(self, request):
qs = super(CAdmin, self).queryset(request)
return qs.select_related('a', 'b')
}}}
has no effect, as `ChangeList.get_query_set()` blindly overrides it with a
plain `select_related()` (see
[source:django/trunk/django/contrib/admin/views/main...@10407#l201]).
To get the desired behviour of pulling in the nullable relations in a
single query, three-valued logic is required for
`ModelAdmin.list_select_related`:
* `True` -- always call `select_related()`,
* `False` (the default) -- call `select_related()` if any of the fields
in `list_display` is a foreign key,
* `None` (added) -- leave the queryset alone.
Patch attached.
See also #10722 and http://groups.google.com/group/django-
developers/browse_thread/thread/e1762a77979f7cbe .
--
Ticket URL: <http://code.djangoproject.com/ticket/10742>
Django <http://code.djangoproject.com/>
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