小部件库捕获的异常
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【中文标题】小部件库捕获的异常【英文标题】：Exception Caught by widgets library 【发布时间】：2019-06-13 17:25:58 【问题描述】：从 API 获取数据并使用 ListView 列出数据时出现异常
当我给 itemCount 的数据少于获取的总数据时，它可以正常工作，并且在没有任何无限滚动的情况下显示少一个元素，否则它会在无限滚动时显示错误，这里是代码：
Expanded(
child: StreamBuilder(
initialData: 'https://www.triply.fun/tc-api/adpepv/tickets_info/20/1/',
stream: apiURL,
builder: (context, snapshotVal)
return Container(
child: FutureBuilder<List<TicketsInfo>>(
future: ticketInfo(snapshotVal.data),
builder: (context, snapshot)
return (snapshot.hasData &&
snapshot.data.length != null && snapshot.data.length > 0 )
? ListView.builder(
scrollDirection: Axis.vertical,
shrinkWrap: true,
padding: EdgeInsets.only(bottom: 20),
itemBuilder: (context, int index)
return GestureDetector(
onTap: () => Navigator.pushNamed(
context, "/Detail"),
child: Column(
children: <Widget>[
Container(
height: 1,
color: Colors.black12,
),
Container(
padding:
EdgeInsets.all(0),
margin: EdgeInsets.all(0),
child: Row(
children: <Widget>[
Expanded(
child: Container(
padding: EdgeInsets
.symmetric(
horizontal:
20),
alignment: Alignment
.centerLeft,
child: Text(
"$snapshot.data[index].data.buyerFirst $snapshot.data[index].data.buyerFirst",
style: textStyle(
kColor_dark_text,
FontWeight
.w400,
16),
),
height: 74,
),
),
Container(
width: 40,
child: Image.asset(
ic_forward,
fit: BoxFit
.contain,
height: 10,
width: 6,
),
),
Padding(
padding: EdgeInsets
.only(
left: 10))
],
)),
],
),
);
,
itemCount: snapshot.data.length)
: Center(
child: CircularProgressIndicator(
valueColor:
AlwaysStoppedAnimation<Color>(
kColor_green_theme)));
));
),
)
这是我得到的运行错误：
I/flutter (17054): url 得到了https://www.triply.fun/tc-api/adpepv/tickets_info/20/1/ I/flutter (17054)：数据获取 ['TicketsInfo' 实例、'TicketsInfo' 实例、'TicketsInfo' 实例、'TicketsInfo' 实例、'TicketsInfo' 实例、'TicketsInfo' 实例、'TicketsInfo' 实例'，'TicketsInfo' 的实例，'TicketsInfo' 的实例，'TicketsInfo' 的实例，'TicketsInfo' 的实例] I/flutter (17054)：══╡ 小部件库发现异常╞══════════════════════════════════════════════════════ ═════════════════════════ I/flutter (17054)：以下 NoSuchMethodError 被抛出构建： I/flutter (17054)：在 null 上调用了 getter 'buyerFirst'。 I/颤振（17054）：接收器：空 I/flutter (17054)：尝试调用：buyerFirst 我/颤振（17054）： I/flutter (17054)：抛出异常时，这是堆栈： I/flutter (17054): #0 Object.noSuchMethod (dart:core/runtime/libobject_patch.dart:50:5) I/flutter (17054): #1 _ListScreenState.build... (package:check_in/src/screens/list_screen.dart:141:94) I/flutter (17054): #2 SliverChildBuilderDelegate.build (package:flutter/src/widgets/sliver.dart:397:15) I/flutter (17054)：#3 SliverMultiBoxAdaptorElement._build。 （包：flutter/src/widgets/sliver.dart:1000:67） I/flutter (17054): #4 _HashMap.putIfAbsent (dart:collection/runtime/libcollection_patch.dart:143:29) I/flutter (17054): #5 SliverMultiBoxAdaptorElement._build (package:flutter/src/widgets/sliver.dart:1000:26) I/flutter (17054)：#6 SliverMultiBoxAdaptorElement.createChild。 （包：flutter/src/widgets/sliver.dart:1013:55） I/flutter (17054): #7 BuildOwner.buildScope (package:flutter/src/widgets/framework.dart:2266:19) I/flutter (17054): #8 SliverMultiBoxAdaptorElement.createChild (package:flutter/src/widgets/sliver.dart:1006:11) I/flutter (17054)：#9 RenderSliverMultiBoxAdaptor._createOrObtainChild。 （包：flutter/src/rendering/sliver_multi_box_adaptor.dart:274:23） I/flutter (17054)：#10 RenderObject.invokeLayoutCallback。 （包：flutter/src/rendering/object.dart:1730:58） I/flutter (17054): #11 PipelineOwner._enableMutationsToDirtySubtrees (package:flutter/src/rendering/object.dart:799:15) I/flutter (17054): #12 RenderObject.invokeLayoutCallback (package:flutter/src/rendering/object.dart:1730:13) I/flutter (17054): #13 RenderSliverMultiBoxAdaptor._createOrObtainChild (package:flutter/src/rendering/sliver_multi_box_adaptor.dart:263:5) I/flutter (17054): #14 RenderSliverMultiBoxAdaptor.insertAndLayoutChild (package:flutter/src/rendering/sliver_multi_box_adaptor.dart:401:5) I/flutter (17054): #15 RenderSliverList.performLayout.advance (package:flutter/src/rendering/sliver_list.dart:190:19) I/flutter (17054): #16 RenderSliverList.performLayout (package:flutter/src/rendering/sliver_list.dart:233:19) I/flutter (17054): #17 RenderObject.layout (package:flutter/src/rendering/object.dart:1634:7) I/flutter (17054): #18 RenderSliverPadding.performLayout (package:flutter/src/rendering/sliver_padding.dart:182:11) I/flutter (17054): #19 RenderObject.layout (package:flutter/src/rendering/object.dart:1634:7) I/flutter (17054): #20 RenderViewportBase.layoutChildSequence (package:flutter/src/rendering/viewport.dart:405:13) I/flutter (17054): #21 RenderShrinkWrappingViewport._attemptLayout (package:flutter/src/rendering/viewport.dart:1645:12) I/flutter (17054): #22 RenderShrinkWrappingViewport.performLayout (package:flutter/src/rendering/viewport.dart:1608:20) I/flutter (17054): #23 RenderObject.layout (package:flutter/src/rendering/object.dart:1634:7) I/flutter (17054): #24 _RenderProxyBox&RenderBox&RenderObjectWithChildMixin&RenderProxyBoxMixin.performLayout (package:flutter/src/rendering/proxy_box.dart:104:13) I/flutter (17054): #25 RenderObject.layout (package:flutter/src/rendering/object.dart:1634:7) I/flutter (17054): #26 _RenderProxyBox&RenderBox&RenderObjectWithChildMixin&RenderProxyBoxMixin.performLayout (package:flutter/src/rendering/proxy_box.dart:104:13) I/flutter (17054): #27 RenderObject.layout (package:flutter/src/rendering/object.dart:1634:7) I/flutter (17054): #28 _RenderProxyBox&RenderBox&RenderObjectWithChildMixin&RenderProxyBoxMixin.performLayout (package:flutter/src/rendering/proxy_box.dart:104:13) I/flutter (17054): #29 RenderObject.layout (package:flutter/src/rendering/object.dart:1634:7) I/flutter (17054): #30 _RenderProxyBox&RenderBox&RenderObjectWithChildMixin&RenderProxyBoxMixin.performLayout (package:flutter/src/rendering/proxy_box.dart:104:13) I/flutter (17054): #31 RenderObject.layout (package:flutter/src/rendering/object.dart:1634:7) I/flutter (17054): #32 _RenderProxyBox&RenderBox&RenderObjectWithChildMixin&RenderProxyBoxMixin.performLayout (package:flutter/src/rendering/proxy_box.dart:104:13) I/flutter (17054): #33 RenderObject.layout (package:flutter/src/rendering/object.dart:1634:7) I/flutter (17054): #34 _RenderProxyBox&RenderBox&RenderObjectWithChildMixin&RenderProxyBoxMixin.performLayout (package:flutter/src/rendering/proxy_box.dart:104:13) I/flutter (17054): #35 RenderObject.layout (package:flutter/src/rendering/object.dart:1634:7) I/flutter (17054): #36 _RenderProxyBox&RenderBox&RenderObjectWithChildMixin&RenderProxyBoxMixin.performLayout (package:flutter/src/rendering/proxy_box.dart:104:13) I/flutter (17054): #37 RenderObject.layout (package:flutter/src/rendering/object.dart:1634:7) I/flutter (17054): #38 _RenderProxyBox&RenderBox&RenderObjectWithChildMixin&RenderProxyBoxMixin.performLayout (package:flutter/src/rendering/proxy_box.dart:104:13) I/flutter (17054): #39 RenderObject.layout (package:flutter/src/rendering/object.dart:1634:7) I/flutter (17054): #40 RenderFlex.performLayout (package:flutter/src/rendering/flex.dart:798:17) I/flutter (17054): #41 RenderObject._layoutWithoutResize (package:flutter/src/rendering/object.dart:1509:7) I/flutter (17054): #42 PipelineOwner.flushLayout (package:flutter/src/rendering/object.dart:768:18) I/flutter (17054): #43 _WidgetsFlutterBinding&BindingBase&GestureBinding&ServicesBinding&SchedulerBinding&PaintingBinding&SemanticsBinding&RendererBinding.drawFrame (package:flutter/src/rendering/binding.dart:281:19) I/flutter (17054): #44 _WidgetsFlutterBinding&BindingBase&GestureBinding&ServicesBinding&SchedulerBinding&PaintingBinding&SemanticsBinding&RendererBinding&WidgetsBinding.drawFrame (package:flutter/src/widgets/binding.dart:677:13) I/flutter (17054): #45 _WidgetsFlutterBinding&BindingBase&GestureBinding&ServicesBinding&SchedulerBinding&PaintingBinding&SemanticsBinding&RendererBinding._handlePersistentFrameCallback (package:flutter/src/rendering/binding.dart:219:5) I/flutter (17054): #46 _WidgetsFlutterBinding&BindingBase&GestureBinding&ServicesBinding&SchedulerBinding._invokeFrameCallback (package:flutter/src/scheduler/binding.dart:990:15) I/flutter (17054): #47 _WidgetsFlutterBinding&BindingBase&GestureBinding&ServicesBinding&SchedulerBinding.handleDrawFrame (package:flutter/src/scheduler/binding.dart:930:9) I/flutter (17054): #48 _WidgetsFlutterBinding&BindingBase&GestureBinding&ServicesBinding&SchedulerBinding._handleDrawFrame (package:flutter/src/scheduler/binding.dart:842:5) I/flutter (17054): #49 _invoke (dart:ui/hooks.dart:154:13) I/flutter (17054): #50 _drawFrame (dart:ui/hooks.dart:143:3) 我/颤振（17054）：══════════════════════════════════════════════════════════ ══════════════════════════════════════════════════ ═══════
【问题讨论】：
The getter 'buyerFirst' was called on null.
【参考方案1】：
您可以删除buyerFirst之前的数据，然后重试：
$snapshot.data[index]**.data**.buyerFirst
$snapshot.data[index].data.buyerFirst
替换为：
$snapshot.data[index].buyerFirst $snapshot.data[index].buyerFirst
【讨论】：
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