How do I add a document reference with an auto generated ID when writing a batch in Firebase?

user_12951246 0
Viewed 486

When doing normal transactions in Firebase you can just use the .add function to add a new document with an auto generated ID; however, when doing a batch write with Web version 9 of the API I cannot find any documentation on how to add a new document with a auto generated ID. Currently I have the following code which is not working:

let ref = doc(db, "projects", doc())
batch.add(ref, element);
await batch.commit();

This throws the error "Function doc() cannot be called with an empty path.". In Web version 8 this worked apparently by just calling .doc(). How does one accomplish this?

google-cloud-firestore firebase
3 Answers

This is what worked for me:

let ref = doc(collection(db, "projects"))

user_129512460

According to the Firebase documentation on adding a document:

In some cases, it can be useful to create a document reference with an auto-generated ID, then use the reference later. For this use case, you can call doc():

import { collection, doc, setDoc } from "firebase/firestore"; 

// Add a new document with a generated id
const newCityRef = doc(collection(db, "cities"));

// later...
await setDoc(newCityRef, data);

So it seems you'll need:

let ref = doc(db, collection("projects"))
user_2091030

For Node.js, or using the Firebase V8 syntax, a working solution would be:

let ref = db.collection("projects").doc()
batch.set(ref, {...data})
...
user_153707990
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