How to add multiple docs to a collection in firebase? - reactjs

Question

Im working with React native and react-native-firebase
My objective is to add multiple docs(objects) to a collection at once.
Currently, I have this:
const array = [
{
name: 'a'
},{
name: 'b'
}
]
array.forEach((doc) => {
firebase.firestore().collection('col').add(doc);
}
This triggers an update on other devices for each update made to the collection.
How can I batch these docs together for ONE update?

Answer 1

You can create batch write like
var db = firebase.firestore();
var batch = db.batch()
in you array add updates
array.forEach((doc) => {
var docRef = db.collection("col").doc(); //automatically generate unique id
batch.set(docRef, doc);
});
finally you have to commit that
batch.commit()

Answer 2

You can execute multiple write operations as a single batch that contains any combination of set(), update(), or delete() operations. A batch of writes completes atomically and can write to multiple documents.
var db = firebase.firestore();
var batch = db.batch();
array.forEach((doc) => {
batch.set(db.collection('col').doc(), doc);
}
// Commit the batch
batch.commit().then(function () {
// ...
});

Answer 3

Version 9 of Web API is slightly different, the docs include this example:
import { writeBatch, doc } from "firebase/firestore";
// Get a new write batch
const batch = writeBatch(db);
// Set the value of 'NYC'
const nycRef = doc(db, "cities", "NYC");
batch.set(nycRef, {name: "New York City"});
// Update the population of 'SF'
const sfRef = doc(db, "cities", "SF");
batch.update(sfRef, {"population": 1000000});
// Delete the city 'LA'
const laRef = doc(db, "cities", "LA");
batch.delete(laRef);
// Commit the batch
await batch.commit();

Answer 4

The batch from database also has a create function that adds a new document in a collection and throws an error if there is already a document. we just need the reference to the document. Please note that this function exists in admin sdk of firebase.
const batch = db.batch();
await users.map(async (item)=> {
const collectionRef = await db.collection(COLLECTION_NAME).doc();
batch.create(collectionRef, item);
});
const result = await batch.commit();

Answer 5

A batched write can contain up to 500 operations. Each operation in the batch counts separately towards your Cloud Firestore usage.
Note: For bulk data entry, use a server client library with parallelized individual writes. Batched writes perform better than serialized writes but not better than parallel writes. You should use a server client library for bulk data operations and not a mobile/web SDK.