Export mongodb collection data and import it back using node js

This code will read the documents from the MongoDB collection (the export functionality) and then writes to a file as JSON. This file is used to read (the import functionality) and insert the JSON into another collection. The code uses MongoDB NodeJS driver.

The Export:

Reads from the collection inCollection based upon a supplied query, and writes to a file as JSON "out_file.json".

const MongoClient = require('mongodb').MongoClient;const fs = require('fs');const dbName = 'testDB';const client = new MongoClient('mongodb://localhost:27017', { useUnifiedTopology:true });client.connect(function(err) {    //assert.equal(null, err);    console.log('Connected successfully to server');    const db = client.db(dbName);    getDocuments(db, function(docs) {            console.log('Closing connection.');        client.close();                // Write to file        try {            fs.writeFileSync('out_file.json', JSON.stringify(docs));            console.log('Done writing to file.');        }        catch(err) {            console.log('Error writing to file', err)        }    });}const getDocuments = function(db, callback) {    const query = { };  // this is your query criteria    db.collection("inCollection")      .find(query)      .toArray(function(err, result) {           if (err) throw err;           callback(result);     }); };

The Import:

Reads the exported "out_file.json" file and inserts the JSON data in to the outCollection.

client.connect(function(err) {    const db = client.db(dbName);    const data = fs.readFileSync('out_file.json');    const docs = JSON.parse(data.toString());        db.collection('outCollection')        .insertMany(docs, function(err, result) {            if (err) throw err;            console.log('Inserted docs:', result.insertedCount);            client.close();    });});