[Answer]-How to filter objects in Django that do not have any other objects pointing to them?

You could inspect all models to find out which ones have a foreign key on Group and dynamically build the query. Use the model’s _meta get_all_related_objects() to get a list of RelatedObject for your Group model:

>>> related = Group._meta.get_all_related_objects()
>>> print related 
[<RelatedObject: app:itemtypeone related to group>, <RelatedObject: app:itemtypetwo related to van>, <RelatedObject: app:itemtypethree related to group>]

Then build your lookups:

>>> excludes = dict(("%s__isnull" % ro.get_accessor_name(), False) for ro in related)

And execute your query:

>>> filtered = Group.objects.exclude(**excludes)

(warning: mostly untested code, might need some tweaking).