Gfrktyl

I am trying to setup a Mongo Connection to an Express App which would be deployed on Google App-Engine. I noticed some approaches like this:

// Initialize connection once

MongoClient.connect("mongodb://localhost:27017/integration_test", function(err, database) {

  if(err) return console.error(err);

  db = database;

// Reuse database object in request handlers

app.get("/", function(req, res, next) {

  db.collection("replicaset_mongo_client_collection").find({}, function(err, docs) {

    if(err) return next(err);

    docs.each(function(err, doc) {

      if(doc) {

        console.log(doc);

      }

      else {

        res.end();

      }

    });

  });

});

I had some concerns about DB server outages and how it would be able to handle those. Thankfully, Node MongoDB client reconnects when DB Server is up. The only issue is that when DB server is down, the requests take a lot of time to process.

I came up with a solution, which probably works. Just wanted to know If I am doing anything wrong(Ignore the messages) or is there any better way?

let mongoConn = null;

const getMongoConn = async() => {

    if(!mongoConn) {

        try {

            mongoConn = await MongoClient.connect("mongodb://localhost:27017", { useNewUrlParser: true });

            mongoConn.on("close", () => {

                console.log("Mongo Connection closed.");

                mongoConn = null;

            })

        } catch(err) {

            console.error("Mongo Connection failed.");

            return null;

        }

    }

    return mongoConn;

}



const app = express();

app.get("/", async(req, res) => {

    console.log("recieved");

    const conn = await getMongoConn();

    try {

        const db = conn.db("testDb");

        const result = await db.collection("test").find().toArray();

        res.status(200).send(JSON.stringify(result)).end();

    } catch (e) {

        res.status(404).send("DB server is down").end();

    }

});



app.listen(7000, () => console.log("Server started."));