How can i upload multiple images to firebase in flutter and get all their download urls

Question

Here is my upload function. My desired output is a list of all urls, but it returns an empty list. I have tried different suggested solutions, but all of them have failed.

Future<List<String>> uploadFiles(List _images) async {
  List<String> imagesUrls=[];

   _images.forEach((_image) async{
    StorageReference storageReference = FirebaseStorage.instance
        .ref()
        .child('posts/${_image.path}');
    StorageUploadTask uploadTask = storageReference.putFile(_image);
    await uploadTask.onComplete;

     imagesUrls.add(await storageReference.getDownloadURL());
     
  });
print(imagesUrls);
return imagesUrls;
}

Answer 1

I think you'll need Future.wait to ensure all futures are resolved before continuing:

Future<List<String>> uploadFiles(List<File> _images) async {
  var imageUrls = await Future.wait(_images.map((_image) => uploadFile(_image)));
  print(imageUrls);
  return imageUrls;
}

Future<String> uploadFile(File _image) async {
  StorageReference storageReference = FirebaseStorage.instance
      .ref()
      .child('posts/${_image.path}');
  StorageUploadTask uploadTask = storageReference.putFile(_image);
  await uploadTask.onComplete;

  return await storageReference.getDownloadURL();
}