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 document

const firestore = admin.firestore() firestore.collection("products").get().then(query => {   query.forEach(function(doc) {     var promise = firestore.collection(uid).doc(doc.data().barcode).set(doc.data());   }); }); 

is there a shorter version? to just copy the whole collection at once?

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)); 

Answer 2

Currently, no. Looping through each document using Cloud Functions and then setting a new document to a different collection with the specified data is the only way to do this. Perhaps this would make a good feature request.

How many documents are we talking about? For something like 10,000 it should only take a few minutes, tops.