Batch Operations with FlutterFire

Sometimes you need to make batch operations like you want to add a list in a single go. Adding a list in a loop with multiple backend calls is not a good way to do it. Luckily firestore allows you to make batch operations.

As Firebase documentation says you execute multiple write operations as a single batch that can contain any combination of set, update, or delete operations.

We will take an example of List of Cities to understand it better.

class City {
 String id;
 String name;
City({this.name}) :id=null;
City.fromSnapshot(DocumentSnapshot doc) : assert(doc != null),
 id = doc.id,
 name = doc.data()[‘name’];
}

First, create a new batch instance via the batch method, then perform the operations on the batch, and then commit it once ready.

Adding in batch

void addBatchCities() {
  final CitiesRef = FirebaseFirestore.instance.collection(COLLECTION_CITIES);
  WriteBatch batch = FirebaseFirestore.instance.batch();
  final cities = getCities();
  for (City city in cities) {
    final newCityItem = CitiesRef.doc();
    batch.set(newCityItem, {
      'name': city.name,
      'createdAt': DateTime.now().millisecondsSinceEpoch
    });
  }
  batch.commit();
}

Updating in batch

Future<void> updateBatchCities() {
  final CitiesRef = FirebaseFirestore.instance.collection(COLLECTION_CITIES);
  WriteBatch batch = FirebaseFirestore.instance.batch();

  return CitiesRef.get().then((querySnapshot) {
    var count = 0;
    querySnapshot.docs.forEach((document) {
      batch.update(document.reference, {'name': 'City${count++}'});
    });

    return batch.commit();
  });
}

Deleting in batch

Future<void> deleteBatchCities() {
 final CitiesRef = FirebaseFirestore.instance.collection(COLLECTION_CITIES);
 WriteBatch batch = FirebaseFirestore.instance.batch();
 return CitiesRef.get().then((querySnapshot) {
 querySnapshot.docs.forEach((document) {
 batch.delete(document.reference);
 });
 return batch.commit();
 });
}

For Complete code:
https://github.com/BilalSiddiqui/Firestore-Batch-Operations

Thanks for reading. Just clap if you like it.

Follow me for more Firebase, Flutter and Android articles.