How to configure mongodb for flask_session?

i configured flask sessions to use mongo db to store session values but upon running the code i am getting folowing error

Traceback (most recent call last):
  File "/home/neo/simulation_loader/simulation2/Pratham/coding/cs50_final/django/env/lib/python3.10/site-packages/flask/app.py", line 2095, in __call__
    return self.wsgi_app(environ, start_response)
  File "/home/neo/simulation_loader/simulation2/Pratham/coding/cs50_final/django/env/lib/python3.10/site-packages/flask/app.py", line 2080, in wsgi_app
    response = self.handle_exception(e)
  File "/home/neo/simulation_loader/simulation2/Pratham/coding/cs50_final/django/env/lib/python3.10/site-packages/flask/app.py", line 2077, in wsgi_app
    response = self.full_dispatch_request()
  File "/home/neo/simulation_loader/simulation2/Pratham/coding/cs50_final/django/env/lib/python3.10/site-packages/flask/app.py", line 1526, in full_dispatch_request
    return self.finalize_request(rv)
  File "/home/neo/simulation_loader/simulation2/Pratham/coding/cs50_final/django/env/lib/python3.10/site-packages/flask/app.py", line 1547, in finalize_request
    response = self.process_response(response)
  File "/home/neo/simulation_loader/simulation2/Pratham/coding/cs50_final/django/env/lib/python3.10/site-packages/flask/app.py", line 1892, in process_response
    self.session_interface.save_session(self, ctx.session, response)
  File "/home/neo/simulation_loader/simulation2/Pratham/coding/cs50_final/django/env/lib/python3.10/site-packages/flask_session/sessions.py", line 456, in save_session
    self.store.update({'id': store_id},
  File "/home/neo/simulation_loader/simulation2/Pratham/coding/cs50_final/django/env/lib/python3.10/site-packages/pymongo/collection.py", line 3166, in __call__
    raise TypeError(
TypeError: 'Collection' object is not callable. If you meant to call the 'update' method on a 'Collection' object it is failing because no such method exists.

here is my code for mongo configration

# Set up database
client = pymongo.MongoClient(f"mongodb+srv://recommender:{DB_PASSWORD}@userdata.r8hvj.mongodb.net/{DB_NAME}?retryWrites=true&w=majority")
db = client.user_login_system

#session config
app.config["SESSION_PERMANENT"] = False
app.config["SESSION_TYPE"] = "mongodb"
app.config["SESSION_MONGODB"] = client
app.config["SESSION_MONGODB_DB"] = 'userData'
app.config["SESSION_MONGODB_COLLECTION"] = 'sessions'
Session(app)

and here is how my login route functions

def login(self):
        user = db.users.find_one({"email":request.form.get("email")})
        if user:
            if pbkdf2_sha256.verify(request.form.get("password"), user["password"]):
                return self.start_session(user)
            else:
                return jsonify({"error":"Invalid password"}),400
        else:
            return jsonify({"error":"Invalid username"}),400

def start_session(self,user):
        del user["password"]
        session['logged_in'] = True
        session['user'] = user
        return jsonify(user),200