Can't insert JSON file into MongoDB's collection throught Node driver

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I'm trying to read files from my disk and push it into MongoDB's collections, but connection closing before it done and I get error: MongoError: Topology is closed, please connect.

async function launch() {
  try {
    await mongo.connect();
    console.log("Connection established");

    const database = mongo.db('task');

    const firstCol = database.collection('first');
    const secondCol = database.collection('second');

    const insertIntoCollection = async (file, col) => {
            fs.readFile(file, async function(err, data) {
                if (err) throw err;

                const json = JSON.parse(data);

                const result = await col.insertMany(json);

                console.log(result.insertCount);
            });
    }

        await insertIntoCollection('data/first.json', firstCol);
        await insertIntoCollection('data/second.json', secondCol);
    } finally {
    await mongo.close();
  }
}

launch().catch(console.dir);

What am I doing wrong?

node.js mongodb json
1 Answers

In the above case mongo client will close before the insertIntoCollection function trigger since it is a promise function and promise will not over before the finally trigger.I hope below code will fulfil your expectations.

async function launch() {
    try {
        await mongo.connect();
        console.log("Connection established");

        const database = mongo.db('task');

        const firstCol = database.collection('first');
        const secondCol = database.collection('second');


        const insertIntoCollection = async (file, col) => {
            return new Promise((resolve, reject) => {
                fs.readFile(file, async (err, data) => {
                    try {
                        if (err) reject(err);
                        const json = JSON.parse(data);
                        const result = await col.insertMany(json);
                        console.log(result.insertCount);
                        resolve(result.insertCount)
                    } catch (err) {
                        reject(err)
                    }
                });
            })
        }
        await insertIntoCollection('data/first.json', firstCol);
        await insertIntoCollection('data/second.json', secondCol);
    } finally {
        await mongo.close();
    }
}

launch().catch(console.dir);
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