backend/expense_tracker/utils.py

from pymongo import MongoClient
from django.conf import settings

class MongoDBClient:
    _instance = None

    @staticmethod
    def get_client():
        if MongoDBClient._instance is None:
            config = settings.MONGODB_SETTINGS
            client = MongoClient(config['URI'])
            MongoDBClient._instance = client[config['DB_NAME']]
        return MongoDBClient._instance

    @staticmethod
    def get_collection(collection_name):
        db = MongoDBClient.get_client()
        return db[collection_name]