Flutter-Firestore：一次更新多个文档

Question

I am pretty new to Flutter and I have spent some time on this and cannot find a clear answer for what I am trying to do. I am querying a collection for a couple of docs and then trying to update them using the batch function. However, I am having trouble understanding the documentation and previous answers on how exactly to use the batch function in Flutter with Firestore with multiple docs. The query seems to be working and returning the docs, but the batch.update() is throwing an error that I cannot figure out how to solve. Here is what I have

InkWell(
 onTap: () async {
  final batch = FirebaseFirestore.instance.batch();
  var pushNotifications = await FirebaseFirestore.instance
    .collection('collection name')
    .where(first filter)
    .where(second filter)
    .get();
print(pushNotifications.docs.length);
//this is where the error is occuring when trying to update the batch
  for (var postDocs in pushNotificiations.docs) {
     batch.update(postDocs.reference, {
     "user_refs" : usersInchallenge
   }
   );
await batch.commit();
)

UPDATE: I am getting closer but now it is only updating the first document of the batch and not the rest. It is giving the error below with the udpated code snippet.

[VERBOSE-2:dart_vm_initializer.cc(41)] Unhandled Exception: Bad state: This batch has already been committed and can no longer be changed.

Answer 1

After banging my head against a wall for a few hours, here is what finally worked with batch() after querying multiple docs.

final batch = FirebaseFirestore.instance.batch();
var pushNotificiations = await FirebaseFirestore.instance
  .collection('ff_user_push_notifications')
  .where(filter 1)
  .where(filter 2)
  .get();

print(pushNotificiations.docs.length);

pushNotificiations.docs.forEach((doc) => {
batch.update(doc.reference, {
"user_refs" : usersInchallenge
  }),
});

batch.commit();