Upload multiple images to Firebase Storage AT ONCE-CodePudding

There are some questions posted about uploading multiple files to Firebase, but all the solutions I came across use a forEach loop or something similar to upload one by one. However, if I'm uploading files that depend on each other (say, my app requires both of them to exist to function correctly), this could be an issue because one of the uploads could succeed and the other fail.

I thought there must be a way to do something similar to a batch write in Firestore but for uploading files in Firebase Storage.

Is there any way to do that or is the loop method the only way?

(I'm using Flutter, so if possible I would appreciate it if any code provided as an answer is written in Dart)

CodePudding user response：

Well, you could use Future.wait() to upload your files simultaneously without waiting for any of them to complete before you begin other.

To explain further, I made the following code snippet, please follow along:

void main() {
  Future.wait([
    uploadImage1(),
    uploadImage2(),
    uploadImage3(),
  ]);
}

Future<void> uploadImage1() async {
  await Future.delayed(Duration(seconds: 3), () {
    print('1');
  });
}

Future<void> uploadImage2() async {
  throw Exception();
}

Future<void> uploadImage3() async {
  await Future.delayed(Duration(seconds: 3), () {
    print('3');
  });
}

I made three async operations, and added them all to Future.wait list, so all are executed/triggered at the same time, doesn't matters if any of them fails. Try the code on dart pad and you will see the output appears at the same time, the output would look like:

1
3
: ExceptionError: Exception

On the other hand, if you want to wait for one operation to successfully finish, then you can use await on a method that returns Future, so it will wait until the operation is successfully completed.

void main() async {
   await uploadImage1();
   await uploadImage2();
   await uploadImage3();
}

Future<void> uploadImage1() async {
  await Future.delayed(Duration(seconds: 3), () {
    print('1');
  });
}

Future<void> uploadImage2() async {
  throw Exception();
}

Future<void> uploadImage3() async {
  await Future.delayed(Duration(seconds: 3), () {
    print('3');
  });
}

The output would be:

1
: ExceptionError: Exception