[Django]-How to select orphan records from model where referential integrity is not enforced?

by

3👍

Use the fact that Django allows nested querying:

def Foo(request):
    parent_ids=Parent.objects.values('id')
    orphans=Children.objects.exclude(parent_id__in=parent_ids)
    return render_to_response('Foo.html', {'orphans':orphans})
👤ReWrite

1👍

No answers yet so here’s my attempt to answer my own question

Here is an ugly solution that works…

def Foo(request):
    orphans=[]
    for child in Children.objects.all():
        try:
            if child.parent:
                pass
        except Parent.DoesNotExist:
            orphans.append(child)
    return render_to_response('Foo.html',{'orphans':orphans})

Hopefully there is a better way?

Update improved method…

def Foo(request):
    parent_id_list=[row.pk for row in Parent.objects.all()]
    orphans=Children.objects.exclude(pk__in=parent_id_list)
    return render_to_response('Foo.html',{'orphans':orphans})
👤FxFocus

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