[Fixed]-TypeError at / 'SimpleLazyObject' object is not callable

You have two things called MongoClient: the one you imported from pymongo, and the global class you assigned to a lazy object. But in get_connection, you are attempting to call the first of those, but by then the name has already been rebound to point to the second.

You should change that module-level name to something else.

(Note, none of this has anything to do with Django; it is a pure Python problem.)