flutter - 流生成器不接收数据（无限连接状态 = 等待）颤振

Question

我有一种从火库和存储中获取项目的方法。我进行了一些更改，以便能够使用流构建器刷新列表：

class ItemLab {
  final String tipo;
  final Reference elemento;
  final String pastaVideo;
  final Map video;
  final String imageUrl;

  ItemLab({
    this.tipo,
    this.elemento,
    this.video,
    this.imageUrl,
    this.pastaVideo
  });
}

class LabController {
  final databaseReference = FirebaseFirestore.instance;
  final _storage = FirebaseStorage.instance;
  final picker = ImagePicker();
  bool hasMore = false;
Stream<List<ItemLab>> stream;
  StreamController<List<ItemLab>> _streamController;

  LabController() {
    _streamController = StreamController<List<ItemLab>>.broadcast();
    stream = _streamController.stream..toList();
  }

  void closeStream() {
    _streamController.stream.drain();
  }

  loadLab(String submenu, [int limit]) async* {
    var parts = submenu.split('/');
    var pathSlashless = parts[0].trim();
    var subPathSlashless = parts.sublist(1).join('/').trim();

    var snapshot = await _storage.ref().child("/${submenu}");
    var retorno = await snapshot.listAll();
    List<ItemLab> conteudo = [];

    if(subPathSlashless.isEmpty || subPathSlashless == null){
      retorno.prefixes.forEach((element) {
        conteudo.add(
          ItemLab(
            tipo: 'PASTA',
            elemento: element,
          ),
        );
      });
    }

    for(int i = 0; i < retorno.items.length ; i++){
      var url = await retorno.items[i].getDownloadURL();
      conteudo.add(
        ItemLab(
          tipo: 'FILE',
          elemento: retorno.items[i],
          imageUrl: url,
        ),
      );

      if(limit != null){
        if(conteudo.length > limit){
          hasMore = true;
          yield conteudo;
        }else{
          hasMore = false;
          print("less than 9");
        }
      }
    }


      if(subPathSlashless.isNotEmpty){
        print(subPathSlashless);
        List items;
        await databaseReference
            .collection("lab_${pathSlashless}_url")
            .snapshots().forEach((element) {
              element.docs.forEach((f) {
                if(f.data()['videos'] != null){
                    items == null ? items = f.data()['videos'] :
                    items.addAll(f.data()['videos']);
                  };
                  print("ITEMS :::: >>> ${items}");
              });
        });


        for(int i = 0; i < items.length; i ++){
          //print(items[i]);
          conteudo.add(
            ItemLab(
              tipo: 'VIDEO',
              elemento: null,
              video: items[i],
            ),
          );
        }

      }else{
        await databaseReference
            .collection("lab_${pathSlashless}_url")
            .snapshots().forEach((element) {
          element.docs.forEach((f) {
            if(f.data().isNotEmpty){
              //print(f.data());
              if(f.data().keys.contains("videos")){
                conteudo.add(
                  ItemLab(
                      tipo: 'PASTA',
                      pastaVideo: findFolderName(f.reference.path)
                  ),
                );
                _streamController.add(conteudo);
              }else{
                conteudo.add(
                  ItemLab(
                    tipo: 'VIDEO',
                    elemento: null,
                    video: f.data(),
                  ),
                );
                _streamController.add(conteudo);
              }
            }
          });
        });
      }

    pathSlashless = null;
    subPathSlashless = null;

    conteudo = checkDuplicateFolder(conteudo, submenu);
    yield conteudo;
  }

我想在这个列表中显示它：

LabController ctrlLab = LabController();

loadBasicStructure(submenu ,callback, context, scrollController, deviceSize){
return StreamBuilder(
      stream: ctrl.stream,
      builder: (ctx, snapshot) {
        if (snapshot.connectionState == ConnectionState.waiting) {
          return Center(child: CircularProgressIndicator());
        }

但是使用这种方法，列表永远不会被填充。它总是显示 CircularProgressIndicator 但不显示项目..所以我在这里缺少什么？

标签： flutterdart