[Answer]-Django relation syntax comparison

As @yuvi mentioned Foo.bar.filter(date=...) is invalid. Maybe the first query would be like:

Foo.bar.get_query_set().filter(date=...)

Foo.bar.get_query_set() will generate a query set for bar which is same as Bar.objects.all(). Thus these two are completely different.

Foo.bar.filter does not exists since Foo.bar exists to get description about the field.