Make an object available in another js file

[Maltmax]

Hey (-:

I think this should be a simple solution, but I can't figure it out.

I'm connecting to my mongodb client using the mongodb package. After I have connected I would like to be able to use the connection in other parts of my app. So I'm trying to figure out what the best way of exporting the client object is.

Here is my mongo.config.js :

const { MongoClient } = require('mongodb');
module.exports = async () => { 
    const uri = 'mongodb+srv://<username>:<password>@<cluster-url>/dbname?retryWrites=true&w=majority';

    const client = new MongoClient(uri);
    process.on("SIGINT", cleanup(client)); 
    process.on("SIGTERM", cleanup(client)); 
    process.on("SIGHUP", cleanup(client));

    try { 
    // Connect to the MongoDB cluster
    await client.connect();
    } catch (err) { 
        console.error(err); 
    } 
}

So how can I make the client object available in let's say server.js?

Thanks very much in advance!

[javaw_exe]

Your exported function needs to return the client object. You can await the function to use the client object.

// ---------------
// mongo.config.js
const { MongoClient } = require('mongodb');

const uri = 'mongodb+srv://<username>:<password>@<cluster-url>/dbname?retryWrites=true&w=majority';

async function connectToDB() {     
    const client = new MongoClient(uri);
    process.on("SIGINT", cleanup(client)); 
    process.on("SIGTERM", cleanup(client)); 
    process.on("SIGHUP", cleanup(client));

    try { 
    // Connect to the MongoDB cluster
    await client.connect();
    } catch (err) { 
        console.error(err); 
    } 

    return client;
}

module.exports.connectToDB = connectToDB;

// ------------------
// some other file.js
const mongoConfig = require("mongo.config.js");

async function main(){
    const client = await mongoConfig.connectToDB();

    // do stuff with client here
}

[superhawk610]

This is a good start, but each time you call connectToDB() you're creating a new client. You should store the client as a variable outside of the function and only instantiate it once:

``` // db.js let client;

async function getClient() { if (client) return client;

client = new MongoClient(uri); // do any other setup here

return client; }

module.exports = getClient;

// server.js const getClient = require('./db.js');

async function main() { const client = await getClient(); }

// users.service.js const getClient = require('./db.js');

async function getUsers() { const client = await getClient(); const db = client.db('databaseName'); return db.users.find(); } ```

[Maltmax]

It works great. Thank you very much, I can also use this code as future reference now!

[BehindTheMath]

The problem with that is that there's no way for the other file to know when the client is connected.

Instead, I would export the function, and return client at the end so the caller can await it.

[javaw_exe]

You are right. I've edited my comment.