Flutter Firebase upload multiple images

Question

Uploading multiple images and waiting for the URL list, images were loaded to firestore successfully after few seconds and returns the url but before that the future function returns with null

Future<List<dynamic>> uploadImage() async {
     _imageFile.forEach((image) async {
      String rannum = Uuid().v1();
      StorageReference reference =
          FirebaseStorage.instance.ref().child('Reviews').child(rannum);
      StorageUploadTask uploadTask = reference.putFile(image);
      StorageTaskSnapshot downloadUrl = (await uploadTask.onComplete);
      String _url = await downloadUrl.ref.getDownloadURL();
      _urllist.add(_url);
    });

    return _urllist;
  }

Milvintsiss · Accepted Answer · 2020-08-06 23:19:39Z

1

You have to call your function like this:

uploadImage(_imageFile).then((List<String> urls) => urls.forEach((element) => print(element)))

And I also changed your function:

Future<List<String>> uploadImage(List<File> _imageFile) async {
    List<String> _urllist = [];
    await _imageFile.forEach((image) async {
      String rannum = Uuid().v1();
      StorageReference reference =
      FirebaseStorage.instance.ref().child('Reviews').child(rannum);
      StorageUploadTask uploadTask = reference.putFile(image);
      StorageTaskSnapshot downloadUrl = await uploadTask.onComplete;
      String _url = await downloadUrl.ref.getDownloadURL();
      _urllist.add(_url);
    });

    return _urllist;
  }

also I don't understand why you enclosed with brackets "await uploadTask.onComplete"

edited Aug 6, 2020 at 23:19

answered Apr 29, 2020 at 22:43

Milvintsiss

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8 Comments

Flutter_Raj Over a year ago

Thanks, i tried your suggestion, it is not working. Still receiving blank list

Milvintsiss Over a year ago

Yes you have to store your download urls as String not Dynaminc, I updated my answer

Flutter_Raj Over a year ago

I tried this option, still i am facing the same issue. On multiple image upload, the function is not waiting for all the download URLs. I have changed the function with future.delayed.

Milvintsiss Over a year ago

Can you post how you call this Future? Because it's a Future it's async and you have to await for the answer

Flutter_Raj Over a year ago

I am using the .then as uploadImage().then((photourl) {}

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