MongoDB and NodeJS TypeError: mongoClient.close is not a function

Question

When i try to close the connection between NodeJS and MongoDB cluster i get mongoClient.close is not a function. Please help

Node JS MongoDB code

const mongoClient = require("mongodb").MongoClient;

exports.getInfo = async (czytnik_id) => {
    return new Promise((resolve, reject) => {
        mongoClient.connect(process.env.URI, { useUnifiedTopology: true }, (err, db) => {
            if (err) reject(err);
            const dbo = db.db('TTI');
            const res = dbo.collection('3P').findOne({ id: czytnik_id });
            mongoClient.close()
            resolve(res);
        });
    });
}

Answer 1

According to the docs, the callback in MongoClient.connect() takes an error and a connected client instance, which is the one to be closed. In your case, it seems to be db, so try db.close() instead of mongoClient.close().

Answer 2

From the doc mongodb - npm and Connection guide, MongoClient is a class. You need to create a client instance, the .close method is an instance method.

Example:

const { MongoClient } = require('mongodb');
// or as an es module:
// import { MongoClient } from 'mongodb'

// Connection URL
const url = 'mongodb://localhost:27017';
const client = new MongoClient(url);

// Database Name
const dbName = 'myProject';

async function main() {
  // Use connect method to connect to the server
  await client.connect();
  console.log('Connected successfully to server');
  const db = client.db(dbName);
  const collection = db.collection('documents');

  // the following code examples can be pasted here...

  return 'done.';
}

main()
  .then(console.log)
  .catch(console.error)
  .finally(() => client.close());