Dart 如果嵌套在子项中，则不会呈现StreamBuilder小部件：<；Widget>；[]

我正在尝试从Firebase的FireStore数据库读取数据，并在Flatter应用程序中显示为列表

我遇到了这个问题，需要将StreamBuilder作为Widget数组的一部分。如果StreamBuilder小部件作为小部件的单个子部件，则会呈现OK。但是如果它是子窗口小部件数组的一部分，它就不起作用。e、 g

下面是我的小部件，它使用StreamBuilder

Widget postsListWidget = new StreamBuilder(
        stream: Firestore.instance.collection('baby').snapshots(),
        builder: (context, snapshot) {
          if (!snapshot.hasData) return const Text('Loading...');
          return new ListView.builder(
            itemCount: snapshot.data.documents.length,
            padding: const EdgeInsets.only(top: 10.0),
            itemExtent: 55.0,
            itemBuilder: (context, index) =>
                _buildListItem(context, snapshot.data.documents[index]),
          );
        });

下面是我在使用StreamBuilder小部件时使用的单子级父项，例如容器

return new Scaffold(
        body: new Container(
      child: postsListWidget,
    )

上述代码可以正常工作，因为容器只有一个“子”元素

但是，如果我使用另一个小部件，该小部件可以有多个子部件，例如行，StreamBuilder将不会渲染。e、 g

 return new Scaffold(
        body: new Row(
      children: <Widget>[postsListWidget],
    )

---

如果有人能帮忙，我会很感激的，我就是找不到谷歌来帮我

我认为您缺少对错误和数据的检查，这些错误和数据尚未可用，如中所示

新建StreamBuilder(
流：\ u lot？.bids，//流或空
生成器：（BuildContext上下文，异步快照）{
if（snapshot.hasError）
返回新文本（'Error:${snapshot.Error}'）；
交换机（快照.连接状态）{
case ConnectionState.none：返回新文本（“选择批次”）；
case ConnectionState.waiting：返回新文本（'waiting bids…'）；
case ConnectionState.active：返回新文本（“\$${snapshot.data}”）；
case ConnectionState.done：返回新文本（“\$${snapshot.data}（closed）”；
}
},
)

---

Widget-postslitwidget=new StreamBuilder（

看起来可疑。你在用

postslitwidget

做什么？我正在尝试从firebase FireStore数据库获取流并显示在列表中。因为它在行->子数组下不工作，所以我为来自数据库的帖子创建了一个单独的小部件，即postslitwidget！

flutter: Another exception was thrown: RenderBox was not laid out: RenderViewport#9162d NEEDS-LAYOUT NEEDS-PAINT
flutter: Another exception was thrown: RenderBox was not laid out: RenderViewport#9162d NEEDS-PAINT
flutter: Another exception was thrown: Tried to paint a RenderObject reentrantly.
flutter: Another exception was thrown: 'package:flutter/src/widgets/text.dart': Failed assertion: line 213 pos 15: 'data != null': is not true.
flutter: Another exception was thrown: Tried to paint a RenderObject reentrantly.

new StreamBuilder<int>(
  stream: _lot?.bids, // a Stream<int> or null
  builder: (BuildContext context, AsyncSnapshot<int> snapshot) {
    if (snapshot.hasError)
      return new Text('Error: ${snapshot.error}');
    switch (snapshot.connectionState) {
      case ConnectionState.none: return new Text('Select lot');
      case ConnectionState.waiting: return new Text('Awaiting bids...');
      case ConnectionState.active: return new Text('\$${snapshot.data}');
      case ConnectionState.done: return new Text('\$${snapshot.data} (closed)');
    }
  },
)