manually create a Django QuerySet or rather manually add objects to a QuerySet

django django-queryset
chefsmart picture chefsmart · Aug 3, 2010 · Viewed 34k times · Source

Basically I need a graceful way to do the following:- 

obj1 = Model1.objects.select_related('model2').get(attribute1=value1)
obj2 = Model1.objects.select_related('model2').get(attribute2=value2)
model2_qs = QuerySet(model=Model2, qs_items=[obj1.model2,obj2.model2])

I may not be thinking right, but doing something like the following seems infinitely stupid to me.: - 

obj1 = Model1.objects.select_related('model2').get(attribute1=value1)
model2_qs = Model2.objects.filter(pk=obj1.model2.pk)

Yes, I need to end up with a QuerySet of Model2 for later use (specifically to pass to a Django form).

In the first code block above,even if I use filter instead of get I will obviously have a QuerySet of Model1. Reverse lookups may not always be possible in my case.

Answer

JudoWill picture JudoWill · Aug 3, 2010

If you're simply looking to create a queryset of items that you choose through some complicated process not representable in SQL you could always use the __in operator.

wanted_items = set()
for item in model1.objects.all():
    if check_want_item(item):
        wanted_items.add(item.pk)

return model1.objects.filter(pk__in = wanted_items)

You'll obviously have to adapt this to your situation but it should at least give you a starting point.

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