How to Export Multiple or All MongoDB Collections

Recently, I wanted to validate something some data from my MongoDB database locally and convert them to JSON for ease of data manipulation.

So after reading a couple of docs I tried to use mongoexport

Tried running the following command

mongoexport --uri "mongodb+srv://user:password@something.example.mongodb.net/db_name" --collection "accounts" --out accounts.json

And it did work as expected.

Then I tried various things like adding multiple collection names, leaving collection args, and also giving * as a collection.

Nothing did work.

So apparently, mongoexport can only export one collection at a time 😭

How to export multiple collections then?

Well, just export them and then merge them.

It might not be a good solution for large applications but for small projects/side projects, it should get the job done pretty well.

So here is what we do at high level:

Get all the collection names from the DB (automatically fetched)
Loop through all the collection manually and then get all documents from it
Then, stitch data from all collections together and store it in a JSON file.

For the sake of simplicity, I'll be using Node.js and a related MongoDB driver. You can use any tool that you're familiar with.

// backup-all-collections.js
const { MongoClient } = require('mongodb');
const fs = require('fs');

const uri = "mongodb+srv://user:password@something.example.mongodb.net/db_name"

const client = new MongoClient(uri, { useUnifiedTopology: true });

// https://nesin.io/blog/convert-date-to-yyyy-mm-dd-javascript
const convertDate = dt => {
    const year = dt.getFullYear();
    const month = (dt.getMonth() + 1).toString().padStart(2, '0');
    const date = dt.getDate()
    return `${year}-${month}-${date}`
}

async function exportAllCollections() {
    try {
        const fileName = `${convertDate(new Date())}.json`
        await client.connect();
        const db = client.db();
        // This will fetch all the collection names from the database so you don't have to manually keep track of it.
        const collections = await db.listCollections().toArray();
        const data = {};

        for (const collectionInfo of collections) {
            const collectionName = collectionInfo.name;
            const collection = db.collection(collectionName);
            const documents = await collection.find().toArray();
            data[collectionName] = documents;
        }
        fs.writeFileSync(fileName, JSON.stringify(data, null, 2));
    } catch (error) {
        console.error('Error exporting collections:', error);
    } finally {
        await client.close();
    }
}

exportAllCollections();

Happy exporting collections!