TypeError at / 'SimpleLazyObject' object is not callable

I am trying to work on an old version of django with mongodb

Django==1.5.11
django-crispy-forms==1.5.2
django-ifc-rwfm==0.1
django-mongodb-engine==0.6.0
django-registration-redux==1.2
djangotoolbox==1.8.0
pymongo==3.2.2

I am trying to get connection to the database
but it returns : TypeError at / 'SimpleLazyObject' object is not callable

This is my __init__.py file

from django.conf import settings
from django.utils.functional import SimpleLazyObject    

from pymongo import MongoClient    

_connection = None    


def get_connection():
    global _connection
    if not _connection:
        _connection = MongoClient(
            host=getattr(settings, 'MONGODB_HOST', None),
            port=getattr(settings, 'MONGODB_PORT', None)
        )
        username = getattr(settings, 'MONGODB_USERNAME', None)
        password = getattr(settings, 'MONGODB_PASSWORD', None)
        db = _connection[settings.MONGODB_DATABASE]
        if username and password:
            db.authenticate(username, password)
        return db
    return _connection[settings.MONGODB_DATABASE]    


MongoClient = SimpleLazyObject(get_connection)    


def get_collection(collection_name):
    return getattr(MongoClient, collection_name)

I am new to django, thanks in advance.

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.)