Flutter:Streambuilder 被多次调用

Question

我正在开发显示产品的应用程序。该应用程序在 ListView 中有 4 个 block 。每个 block 都展示产品图像及其信息，并且可以水平滚动以获取更多数据。

我有以下示例代码

class Home extends StatefulWidget {
  @override
  State<StatefulWidget> createState() {
    return HomeState();
  }
}

class HomeState extends State<Home> {
    //------- other codes

  @override
  void initState() {
    bloc.fetchNewProperties(0);
    super.initState();
  }

  Widget build(BuildContext context) {


    return Scaffold(
      drawer: CustomDrawer(),
      backgroundColor: Constants.scaffoldColor,
      body: NestedScrollView(
        headerSliverBuilder: (BuildContext context, bool innerBoxIsScrolled) {
          return <Widget>[
            SliverAppBar(
              expandedHeight: 216,
              floating: false,
              titleSpacing: 0.0,
              pinned: true,
              flexibleSpace: Container(
                decoration: BoxDecoration(
                  gradient: LinearGradient(
                      begin: Alignment.topLeft,
                      end: Alignment.bottomRight,
                      colors: [Constants.gradientStart, Constants.gradientEnd]),
                ),
                child: FlexibleSpaceBar(
                  centerTitle: true,
                  background: Swiper(
                    itemBuilder: (BuildContext context, int index) {
                      return new Image.asset(
                        tempBannerImages[index],
                        fit: BoxFit.fill,
                      );
                    },
                    itemCount: 2,
                    pagination: new SwiperPagination(),
                    autoplay: true,
                    autoplayDelay: 8000,
                    autoplayDisableOnInteraction: true,
                  ),
                ),
              ),
            ),
          ];
        },
        body: ListView(
          padding: EdgeInsets.only(
              left: size.getSizePx(10), right: size.getSizePx(10)),
          children: <Widget>[
            newProductsBlock(),
            newProductsBlock(),
            newProductsBlock(),
            newProductsBlock(),
            newProductsBlock(), //have added widget multiple times to make stuff scrollable
          ],
        ),
      ),
    );
  }

    Widget newProductsBlock() {

    print("---This gets called just once---");
    return Column(
      children: <Widget>[

        Text("New Products"),
        Container(
          height: 230,
          child: StreamBuilder(
            stream: bloc.allNewProps,
            builder: (context, AsyncSnapshot<ProductsModel> snapshot) {
              print("--this gets called multiple times.---");
              if (snapshot.hasData) {
                return buildNewPropListSwipe(snapshot);
              } else if (snapshot.hasError) {
                return Text(snapshot.error.toString());
              }
              return showCirularLoadingIndicator();
            },
          ),
        )
      ],
    );
  }

}

问题 产品已成功加载到这些 block 中。但是当我一路向下滚动并回到顶部时。在第一个 block 中，循环加载指示器变得可见，而不是已经加载的项目。当我检查时，我发现当我向下滚动并再次向上滚动时，Streambuilder 被多次调用。

任何人都可以帮助我吗，我对 flutter 还很陌生。

谢谢

Answer 1

对于任何偶然发现同样问题的人，

我将 Parent Listview 更改为 ScrollSingleChildView 并将小部件包装到 Column 中，现在似乎已修复