多个 collections 在 1 个批量写入 firestore

Question

I want to update documents from multiple collections using 1 batched write in Firestore. How can I achieve this? I've seen in Firestore documentation that we can update multiple documents at once using batched write, but how about updating multiple documents in multiple collections at once?

This is what I tried so far, but it is not working,

//Update in User and Monitoring collections
List<WriteBatch> writeBatches = new ArrayList<>();
List<Task<Void>> tasks = new ArrayList<>();
writeBatches.add(db.batch());
List<DocumentSnapshot> documentSnapshotList = task.getResult().getDocuments();

writeBatches.get(batchIndex).update(db.collection("User").document(userId), userMap);
counter++;

for(DocumentSnapshot document : documentSnapshotList){
    Monitoring monitoring = document.toObject(Monitoring.class);

    if(counter == 499){
        tasks.add(writeBatches.get(batchIndex).commit());
        writeBatches.add(db.batch());
        counter = 0;
        batchIndex++;
    }

    writeBatches.get(batchIndex)
            .update(db.collection("Monitoring").document(monitoring.getId()), monitoringMap);
    counter++;
}

Tasks.whenAllSuccess(tasks)
        .addOnCompleteListener(new OnCompleteListener<List<Object>>() {
            @Override
            public void onComplete(@NonNull Task<List<Object>> task) {
                helper.dismissProgressDialog();

                if(task.isSuccessful()){
                    Toast.makeText(EditUserDetailsActivity.this, "Success", Toast.LENGTH_SHORT).show();
                    resetFields();
                    counter = 0;
                    batchIndex = 0;

                    Intent intentforBackButton = NavUtils.getParentActivityIntent(EditUserDetailsActivity.this);
                    intentforBackButton.setFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP | Intent.FLAG_ACTIVITY_SINGLE_TOP);
                    NavUtils.navigateUpTo(EditUserDetailsActivity.this, intentforBackButton);
                }else{
                    Toast.makeText(EditUserDetailsActivity.this, "Failed", Toast.LENGTH_SHORT).show();
                    Log.e("App Error", task.getException().getMessage());
                }
            }
        });

Answer 1

As Doug commented, there is nothing special that is required to write to multiple collections in a batched write or transaction.

So if you'd want to write the same data to another collection int he same batched write, that can be done with:

writeBatches.get(batchIndex)
        .update(db.collection("Monitoring").document(monitoring.getId()), monitoringMap);
writeBatches.get(batchIndex)
        .update(db.collection("AnotherCollection").document(monitoring.getId()), monitoringMap);