Cloud Functions: How to copy Firestore Collection to a new document?

Question

I\'d like to make a copy of a collection in Firestore upon an event using Cloud Functions

I already have this code that iterates over the collection and copies each

Answer 1

I wrote a small nodejs snippet for this.

const firebaseAdmin = require('firebase-admin');
const serviceAccount = '../../firebase-service-account-key.json';
const firebaseUrl = 'https://my-app.firebaseio.com';

firebaseAdmin.initializeApp({
    credential: firebaseAdmin.credential.cert(require(serviceAccount)),
    databaseURL: firebaseUrl
});
const firestore = firebaseAdmin.firestore();

async function copyCollection(srcCollectionName, destCollectionName) {
    const documents = await firestore.collection(srcCollectionName).get();
    let writeBatch = firebaseAdmin.firestore().batch();
    const destCollection = firestore.collection(destCollectionName);
    let i = 0;
    for (const doc of documents.docs) {
        writeBatch.set(destCollection.doc(doc.id), doc.data());
        i++;
        if (i > 400) {  // write batch only allows maximum 500 writes per batch
            i = 0;
            console.log('Intermediate committing of batch operation');
            await writeBatch.commit();
            writeBatch = firebaseAdmin.firestore().batch();
        }
    }
    if (i > 0) {
        console.log('Firebase batch operation completed. Doing final committing of batch operation.');
        await writeBatch.commit();
    } else {
        console.log('Firebase batch operation completed.');
    }
}

copyCollection('customers', 'customers_backup').then(() => console.log('copy complete')).catch(error => console.log('copy failed. ' + error));