Script to dump a firestore collection and import it to your local firestore emulator

firestore-import-export.js

const { backup, restore, initializeApp } = require('firestore-export-import')
const fs = require('fs-extra');

const args = process.argv.slice(2);

if (args.includes('import')) {
    process.env.FIRESTORE_EMULATOR_HOST = 'localhost:8080';
}

// Get this from your firebase project settings
const serviceAccount = require('./adminsdk.json')

// Initiate Firebase App
// appName is optional, you can omit it.
const appName = '[DEFAULT]'
initializeApp(serviceAccount, appName)

const options = {
    docsFromEachCollection: 10, // limit number of documents when exporting
    refs: ['refKey'], // reference Path
}

// which collection to import/export
const collectionName = 'users';

async function main() {
    if (args.includes('import')) {
        if (process.env.FIRESTORE_EMULATOR_HOST === 'localhost:8080') {
            console.log('restoring collection to emulator');
            await restore(`${collectionName}-backup-2021-01-25T14:36:47.527Z.json`);
        }
    } else if (args.includes('export')) {
        console.log('creating backup');
        backup(collectionName).then((data) => {
            const name = `${collectionName}-backup-${new Date().toISOString()}.json`;
            fs.outputFile(name, JSON.stringify(data));
            console.log(`Copy this string to import: ${name}`);
        });
    } else {
        console.error('invalid command');
    }
}

main();