added subscription functionality

src/pages/api/mongodb_client_connection.ts

@@ -0,0 +1,27 @@
+import { MongoClient } from 'mongodb';
+
+const uri = process.env.MONGODB_URI || ''; // Load URI from environment variables
+const options = {};
+
+let client: MongoClient;
+let clientPromise: Promise<MongoClient>;
+
+if (!process.env.MONGODB_URI) {
+  throw new Error('Please add your MongoDB URI to .env.local');
+}
+
+// Reuse the client instance for serverless deployments
+if (process.env.NODE_ENV === 'development') {
+  // Create a global instance to preserve the same client during HMR in development
+  if (!(global as typeof globalThis & { _mongoClientPromise?: Promise<MongoClient> })._mongoClientPromise) {
+      client = new MongoClient(uri, options);
+      (global as typeof globalThis & { _mongoClientPromise?: Promise<MongoClient> })._mongoClientPromise = client.connect();
+  }
+  clientPromise = (global as typeof globalThis & { _mongoClientPromise?: Promise<MongoClient> })._mongoClientPromise!;
+} else {
+  // In production, create a new client connection
+  client = new MongoClient(uri, options);
+  clientPromise = client.connect();
+}
+
+export default clientPromise;