Flutter Charts NoSuchMethodError getter 'length' 被调用为 null
Flutter Charts NoSuchMethodError The getter 'length' was called on null
当我在我的 Flutter 应用程序中转到包含图表的页面，然后转到另一个页面，然后 return 到该页面时，我收到以下错误。然后显示错误。我找不到这个错误的任何原因。因此这是我的代码。
I/flutter ( 8555): ══╡ EXCEPTION CAUGHT BY WIDGETS LIBRARY ╞═══════════════════════════════════════════════════════════
I/flutter ( 8555): The following NoSuchMethodError was thrown building LayoutId-[<chartContainer>](id: chartContainer):
I/flutter ( 8555): The getter 'length' was called on null.
I/flutter ( 8555): Receiver: null
I/flutter ( 8555): Tried calling: length
I/flutter ( 8555):
I/flutter ( 8555): The relevant error-causing widget was:
I/flutter ( 8555): LayoutId-[<chartContainer>]
I/flutter ( 8555): file:///C:/flutter/.pub-cache/hosted/pub.dartlang.org/charts_flutter-0.9.0/lib/src/base_chart_state.dart:116:26
I/flutter ( 8555):
I/flutter ( 8555): When the exception was thrown, this was the stack:
I/flutter ( 8555): #0 Object.noSuchMethod (dart:core-patch/object_patch.dart:51:5)
I/flutter ( 8555): #1 new MutableSeries (package:charts_common/src/chart/common/processed_series.dart:96:30)
I/flutter ( 8555): #2 BaseChart.makeSeries (package:charts_common/src/chart/common/base_chart.dart:514:15)
I/flutter ( 8555): #3 CartesianChart.makeSeries (package:charts_common/src/chart/cartesian/cartesian_chart.dart:286:32)
I/flutter ( 8555): #4 MappedListIterable.elementAt (dart:_internal/iterable.dart:417:31)
I/flutter ( 8555): #5 ListIterator.moveNext (dart:_internal/iterable.dart:343:26)
I/flutter ( 8555): #6 new List.from (dart:core-patch/array_patch.dart:57:19)
I/flutter ( 8555): #7 BaseChart.draw (package:charts_common/src/chart/common/base_chart.dart:450:9)
I/flutter ( 8555): #8 ChartContainerRenderObject.reconfigure (package:charts_flutter/src/chart_container.dart:170:14)
I/flutter ( 8555): #9 ChartContainer.createRenderObject (package:charts_flutter/src/chart_container.dart:62:49)
I/flutter ( 8555): #10 RenderObjectElement.mount (package:flutter/src/widgets/framework.dart:5491:28)
I/flutter ( 8555): #11 SingleChildRenderObjectElement.mount (package:flutter/src/widgets/framework.dart:6117:11)
I/flutter ( 8555): ... Normal element mounting (7 frames)
I/flutter ( 8555): #18 Element.inflateWidget (package:flutter/src/widgets/framework.dart:3569:14)
I/flutter ( 8555): #19 MultiChildRenderObjectElement.mount (package:flutter/src/widgets/framework.dart:6236:32)
I/flutter ( 8555): ... Normal element mounting (15 frames)
I/flutter ( 8555): #34 Element.inflateWidget (package:flutter/src/widgets/framework.dart:3569:14)
I/flutter ( 8555): #35 MultiChildRenderObjectElement.mount (package:flutter/src/widgets/framework.dart:6236:32)
I/flutter ( 8555): ... Normal element mounting (41 frames)
I/flutter ( 8555): #76 Element.inflateWidget (package:flutter/src/widgets/framework.dart:3569:14)
I/flutter ( 8555): #77 Element.updateChild (package:flutter/src/widgets/framework.dart:3327:18)
I/flutter ( 8555): #78 SliverMultiBoxAdaptorElement.updateChild (package:flutter/src/widgets/sliver.dart:1158:36)
I/flutter ( 8555): #79 SliverMultiBoxAdaptorElement.createChild.<anonymous closure> (package:flutter/src/widgets/sliver.dart:1143:20)
I/flutter ( 8555): #80 BuildOwner.buildScope (package:flutter/src/widgets/framework.dart:2683:19)
I/flutter ( 8555): #81 SliverMultiBoxAdaptorElement.createChild (package:flutter/src/widgets/sliver.dart:1136:11)
I/flutter ( 8555): #82 RenderSliverMultiBoxAdaptor._createOrObtainChild.<anonymous closure> (package:flutter/src/rendering/sliver_multi_box_adaptor.dart:350:23)
I/flutter ( 8555): #83 RenderObject.invokeLayoutCallback.<anonymous closure> (package:flutter/src/rendering/object.dart:1883:59)
I/flutter ( 8555): #84 PipelineOwner._enableMutationsToDirtySubtrees (package:flutter/src/rendering/object.dart:915:15)
I/flutter ( 8555): #85 RenderObject.invokeLayoutCallback (package:flutter/src/rendering/object.dart:1883:14)
I/flutter ( 8555): #86 RenderSliverMultiBoxAdaptor._createOrObtainChild (package:flutter/src/rendering/sliver_multi_box_adaptor.dart:339:5)
I/flutter ( 8555): #87 RenderSliverMultiBoxAdaptor.insertAndLayoutChild (package:flutter/src/rendering/sliver_multi_box_adaptor.dart:485:5)
I/flutter ( 8555): #88 RenderSliverList.performLayout.advance (package:flutter/src/rendering/sliver_list.dart:231:19)
I/flutter ( 8555): #89 RenderSliverList.performLayout (package:flutter/src/rendering/sliver_list.dart:274:19)
I/flutter ( 8555): #90 RenderObject.layout (package:flutter/src/rendering/object.dart:1777:7)
I/flutter ( 8555): #91 RenderSliverEdgeInsetsPadding.performLayout (package:flutter/src/rendering/sliver_padding.dart:132:12)
I/flutter ( 8555): #92 RenderSliverPadding.performLayout (package:flutter/src/rendering/sliver_padding.dart:371:11)
I/flutter ( 8555): #93 RenderObject.layout (package:flutter/src/rendering/object.dart:1777:7)
I/flutter ( 8555): #94 RenderViewportBase.layoutChildSequence (package:flutter/src/rendering/viewport.dart:507:13)
I/flutter ( 8555): #95 RenderShrinkWrappingViewport._attemptLayout (package:flutter/src/rendering/viewport.dart:1904:12)
I/flutter ( 8555): #96 RenderShrinkWrappingViewport.performLayout (package:flutter/src/rendering/viewport.dart:1862:20)
I/flutter ( 8555): #97 RenderObject.layout (package:flutter/src/rendering/object.dart:1777:7)
I/flutter ( 8555): #98 RenderProxyBoxMixin.performLayout (package:flutter/src/rendering/proxy_box.dart:113:14)
I/flutter ( 8555): #99 RenderObject.layout (package:flutter/src/rendering/object.dart:1777:7)
I/flutter ( 8555): #100 RenderProxyBoxMixin.performLayout (package:flutter/src/rendering/proxy_box.dart:113:14)
I/flutter ( 8555): #101 RenderObject.layout (package:flutter/src/rendering/object.dart:1777:7)
I/flutter ( 8555): #102 RenderProxyBoxMixin.performLayout (package:flutter/src/rendering/proxy_box.dart:113:14)
I/flutter ( 8555): #103 RenderObject.layout (package:flutter/src/rendering/object.dart:1777:7)
I/flutter ( 8555): #104 RenderProxyBoxMixin.performLayout (package:flutter/src/rendering/proxy_box.dart:113:14)
I/flutter ( 8555): #105 RenderObject.layout (package:flutter/src/rendering/object.dart:1777:7)
I/flutter ( 8555): #106 RenderProxyBoxMixin.performLayout (package:flutter/src/rendering/proxy_box.dart:113:14)
I/flutter ( 8555): #107 RenderObject.layout (package:flutter/src/rendering/object.dart:1777:7)
I/flutter ( 8555): #108 RenderProxyBoxMixin.performLayout (package:flutter/src/rendering/proxy_box.dart:113:14)
I/flutter ( 8555): #109 RenderObject.layout (package:flutter/src/rendering/object.dart:1777:7)
I/flutter ( 8555): #110 RenderProxyBoxMixin.performLayout (package:flutter/src/rendering/proxy_box.dart:113:14)
I/flutter ( 8555): #111 RenderObject.layout (package:flutter/src/rendering/object.dart:1777:7)
I/flutter ( 8555): #112 RenderProxyBoxMixin.performLayout (package:flutter/src/rendering/proxy_box.dart:113:14)
I/flutter ( 8555): #113 RenderObject.layout (package:flutter/src/rendering/object.dart:1777:7)
I/flutter ( 8555): #114 RenderProxyBoxMixin.performLayout (package:flutter/src/rendering/proxy_box.dart:113:14)
I/flutter ( 8555): #115 RenderObject.layout (package:flutter/src/rendering/object.dart:1777:7)
I/flutter ( 8555): #116 RenderProxyBoxMixin.performLayout (package:flutter/src/rendering/proxy_box.dart:113:14)
I/flutter ( 8555): #117 RenderObject.layout (package:flutter/src/rendering/object.dart:1777:7)
I/flutter ( 8555): #118 RenderProxyBoxMixin.performLayout (package:flutter/src/rendering/proxy_box.dart:113:14)
I/flutter ( 8555): #119 RenderObject.layout (package:flutter/src/rendering/object.dart:1777:7)
I/flutter ( 8555): #120 RenderSliverMultiBoxAdaptor.insertAndLayoutLeadingChild (package:flutter/src/rendering/sliver_multi_box_adaptor.dart:457:19)
I/flutter ( 8555): #121 RenderSliverFixedExtentBoxAdaptor.performLayout (package:flutter/src/rendering/sliver_fixed_extent_list.dart:234:32)
I/flutter ( 8555): #122 RenderObject.layout (package:flutter/src/rendering/object.dart:1777:7)
I/flutter ( 8555): #123 RenderSliverEdgeInsetsPadding.performLayout (package:flutter/src/rendering/sliver_padding.dart:132:12)
I/flutter ( 8555): #124 _RenderSliverFractionalPadding.performLayout (package:flutter/src/widgets/sliver_fill.dart:170:11)
I/flutter ( 8555): #125 RenderObject.layout (package:flutter/src/rendering/object.dart:1777:7)
I/flutter ( 8555): #126 RenderViewportBase.layoutChildSequence (package:flutter/src/rendering/viewport.dart:507:13)
I/flutter ( 8555): #127 RenderViewport._attemptLayout (package:flutter/src/rendering/viewport.dart:1561:12)
I/flutter ( 8555): #128 RenderViewport.performLayout (package:flutter/src/rendering/viewport.dart:1470:20)
I/flutter ( 8555): #129 RenderObject._layoutWithoutResize (package:flutter/src/rendering/object.dart:1634:7)
I/flutter ( 8555): #130 PipelineOwner.flushLayout (package:flutter/src/rendering/object.dart:884:18)
I/flutter ( 8555): #131 RendererBinding.drawFrame (package:flutter/src/rendering/binding.dart:436:19)
I/flutter ( 8555): #132 WidgetsBinding.drawFrame (package:flutter/src/widgets/binding.dart:914:13)
I/flutter ( 8555): #133 RendererBinding._handlePersistentFrameCallback (package:flutter/src/rendering/binding.dart:302:5)
I/flutter ( 8555): #134 SchedulerBinding._invokeFrameCallback (package:flutter/src/scheduler/binding.dart:1117:15)
I/flutter ( 8555): #135 SchedulerBinding.handleDrawFrame (package:flutter/src/scheduler/binding.dart:1055:9)
I/flutter ( 8555): #136 SchedulerBinding._handleDrawFrame (package:flutter/src/scheduler/binding.dart:971:5)
I/flutter ( 8555): (elided 3 frames from dart:async)
I/flutter ( 8555):
I/flutter ( 8555): ════════════════════════════════════════════════════════════════════════════════════════════════════
这是我的代码：
import 'dart:convert';
import 'package:Trimlog/app_localizations.dart';
import 'package:Trimlog/models/boat.dart';
import 'package:Trimlog/models/trim.dart';
import 'package:flutter/material.dart';
import 'package:global_configuration/global_configuration.dart';
import 'package:provider/provider.dart';
import 'package:http/http.dart' as http;
import 'package:charts_flutter/flutter.dart' as charts;
Map<String, dynamic> trimOptions = {};
Map<String, dynamic> trimOption = {};
class AnalyticsGraphs extends StatefulWidget {
final Boat boat;
AnalyticsGraphs(this.boat);
@override
_AnalyticsGraphsState createState() => _AnalyticsGraphsState();
}
class _AnalyticsGraphsState extends State<AnalyticsGraphs> {
bool loading = true; // Enable loading
Future getBoatClassTrimTemplate() async {
String boatClassJson = (await http.get(GlobalConfiguration().getValue("static_api")["boatClasses"] + "/" + widget.boat.boatClass)).body;
trimOptions = await json.decode(boatClassJson)["trimTemplate"];
}
@override
void initState() {
super.initState();
getBoatClassTrimTemplate().then((value) {
setState(() {
loading = false;
});
});
} // Execute once on form open
@override
Widget build(BuildContext context) {
final trims = Provider.of<List<Trim>>(context) ?? null;
List<charts.Series<dynamic, num>> series = [
charts.Series(
measureFn: (dynamic trim, _) => trim.weather["windSpeed"],
domainFn: (dynamic trim, _) => trim.trim[trimOption.keys.first],
colorFn: (dynamic trim, _) {
if (trim.satisfaction < 20) {
return charts.ColorUtil.fromDartColor(Colors.red);
} else if (trim.satisfaction < 40) {
return charts.ColorUtil.fromDartColor(Colors.deepOrange);
} else if (trim.satisfaction < 60) {
return charts.ColorUtil.fromDartColor(Colors.orange);
} else if (trim.satisfaction < 80) {
return charts.ColorUtil.fromDartColor(Colors.lightGreen);
} else if (trim.satisfaction <= 100) {
return charts.ColorUtil.fromDartColor(Colors.green);
}
return charts.ColorUtil.fromDartColor(Colors.grey);
},
id: "windSpeed",
data: trims,
),
];
return Column(
children: [
Padding(
padding: const EdgeInsets.fromLTRB(25.0, 10.0, 25.0, 10.0),
child: DropdownButton<String>(
isExpanded: true,
hint: Text(AppLocalizations.of(context).translate("boats.trimOption")),
elevation: 16,
style: Theme.of(context).textTheme.bodyText1,
value: trimOption.isNotEmpty ? trimOption.keys.first : null,
onChanged: (String val) {
setState(() {
trimOption.clear();
trimOption[val] = trimOptions[val];
});
},
items: trimOptions
.map((key, value) {
return MapEntry(
key,
DropdownMenuItem<String>(
value: key,
child: Text(AppLocalizations.of(context).translate(value["labels"]["label"])),
),
);
})
.values
.toList(),
),
),
trimOption.isNotEmpty
? Padding(
padding: const EdgeInsets.fromLTRB(25.0, 10.0, 25.0, 10.0),
child: SizedBox(
height: 400.0,
child: charts.LineChart(
series,
behaviors: [
new charts.ChartTitle(AppLocalizations.of(context).translate(trimOption.values.first["labels"]["label"]),
behaviorPosition: charts.BehaviorPosition.bottom, titleStyleSpec: charts.TextStyleSpec(fontSize: 11), titleOutsideJustification: charts.OutsideJustification.middleDrawArea),
new charts.ChartTitle(AppLocalizations.of(context).translate("weather.windSpeed") + " (" + AppLocalizations.of(context).translate("units.knots") + ")",
behaviorPosition: charts.BehaviorPosition.start, titleStyleSpec: charts.TextStyleSpec(fontSize: 11), titleOutsideJustification: charts.OutsideJustification.middleDrawArea)
],
defaultRenderer: new charts.LineRendererConfig(
includeLine: true,
includePoints: true,
),
animate: false,
animationDuration: Duration(seconds: 0),
defaultInteractions: false,
),
),
)
: Container(),
],
);
}
}
如果我随后切换到另一个页面，我会收到下一个错误，这会使应用程序完全停止工作。
I/flutter ( 8555): Another exception was thrown: 'package:flutter/src/widgets/framework.dart': Failed assertion: line 3427 pos 12: 'child._parent == this': is not true.
I/flutter ( 8555): Another exception was thrown: A RenderViewport expected a child of type RenderSliver but received a child of type RenderErrorBox.
I/flutter ( 8555): Another exception was thrown: 'package:flutter/src/widgets/framework.dart': Failed assertion: line 4345 pos 14: 'owner._debugCurrentBuildTarget == this': is not true.
您的修剪列表为空。所以你不能创建空数据的图表。你也需要检查一下。您的构建方法将如下所示：
@override
Widget build(BuildContext context) {
final trims = Provider.of<List<Trim>>(context) ?? null;
List<charts.Series<dynamic, num>> series = [];
// Here is important!
if (trims != null) {
series = [
charts.Series(
measureFn: (dynamic trim, _) => trim.weather["windSpeed"],
domainFn: (dynamic trim, _) => trim.trim[trimOption.keys.first],
colorFn: (dynamic trim, _) {
if (trim.satisfaction < 20) {
return charts.ColorUtil.fromDartColor(Colors.red);
} else if (trim.satisfaction < 40) {
return charts.ColorUtil.fromDartColor(Colors.deepOrange);
} else if (trim.satisfaction < 60) {
return charts.ColorUtil.fromDartColor(Colors.orange);
} else if (trim.satisfaction < 80) {
return charts.ColorUtil.fromDartColor(Colors.lightGreen);
} else if (trim.satisfaction <= 100) {
return charts.ColorUtil.fromDartColor(Colors.green);
}
return charts.ColorUtil.fromDartColor(Colors.grey);
},
id: "windSpeed",
data: trims,
),
];
}
return Column(
children: [
Padding(
padding: const EdgeInsets.fromLTRB(25.0, 10.0, 25.0, 10.0),
child: DropdownButton<String>(
isExpanded: true,
hint: Text(
AppLocalizations.of(context).translate("boats.trimOption")),
elevation: 16,
style: Theme.of(context).textTheme.bodyText1,
value: trimOption.isNotEmpty ? trimOption.keys.first : null,
onChanged: (String val) {
setState(() {
trimOption.clear();
trimOption[val] = trimOptions[val];
});
},
items: trimOptions
.map((key, value) {
return MapEntry(
key,
DropdownMenuItem<String>(
value: key,
child: Text(AppLocalizations.of(context)
.translate(value["labels"]["label"])),
),
);
})
.values
.toList(),
),
),
trimOption.isNotEmpty && trims != null // Here is important!
? Padding(
padding: const EdgeInsets.fromLTRB(25.0, 10.0, 25.0, 10.0),
child: SizedBox(
height: 400.0,
child: charts.LineChart(
series,
behaviors: [
new charts.ChartTitle(
AppLocalizations.of(context).translate(
trimOption.values.first["labels"]["label"]),
behaviorPosition: charts.BehaviorPosition.bottom,
titleStyleSpec: charts.TextStyleSpec(fontSize: 11),
titleOutsideJustification:
charts.OutsideJustification.middleDrawArea),
new charts.ChartTitle(
AppLocalizations.of(context)
.translate("weather.windSpeed") +
" (" +
AppLocalizations.of(context)
.translate("units.knots") +
")",
behaviorPosition: charts.BehaviorPosition.start,
titleStyleSpec: charts.TextStyleSpec(fontSize: 11),
titleOutsideJustification:
charts.OutsideJustification.middleDrawArea)
],
defaultRenderer: new charts.LineRendererConfig(
includeLine: true,
includePoints: true,
),
animate: false,
animationDuration: Duration(seconds: 0),
defaultInteractions: false,
),
),
)
: Container(),
],
);
当我在我的 Flutter 应用程序中转到包含图表的页面，然后转到另一个页面，然后 return 到该页面时，我收到以下错误。然后显示错误。我找不到这个错误的任何原因。因此这是我的代码。
I/flutter ( 8555): ══╡ EXCEPTION CAUGHT BY WIDGETS LIBRARY ╞═══════════════════════════════════════════════════════════
I/flutter ( 8555): The following NoSuchMethodError was thrown building LayoutId-[<chartContainer>](id: chartContainer):
I/flutter ( 8555): The getter 'length' was called on null.
I/flutter ( 8555): Receiver: null
I/flutter ( 8555): Tried calling: length
I/flutter ( 8555):
I/flutter ( 8555): The relevant error-causing widget was:
I/flutter ( 8555): LayoutId-[<chartContainer>]
I/flutter ( 8555): file:///C:/flutter/.pub-cache/hosted/pub.dartlang.org/charts_flutter-0.9.0/lib/src/base_chart_state.dart:116:26
I/flutter ( 8555):
I/flutter ( 8555): When the exception was thrown, this was the stack:
I/flutter ( 8555): #0 Object.noSuchMethod (dart:core-patch/object_patch.dart:51:5)
I/flutter ( 8555): #1 new MutableSeries (package:charts_common/src/chart/common/processed_series.dart:96:30)
I/flutter ( 8555): #2 BaseChart.makeSeries (package:charts_common/src/chart/common/base_chart.dart:514:15)
I/flutter ( 8555): #3 CartesianChart.makeSeries (package:charts_common/src/chart/cartesian/cartesian_chart.dart:286:32)
I/flutter ( 8555): #4 MappedListIterable.elementAt (dart:_internal/iterable.dart:417:31)
I/flutter ( 8555): #5 ListIterator.moveNext (dart:_internal/iterable.dart:343:26)
I/flutter ( 8555): #6 new List.from (dart:core-patch/array_patch.dart:57:19)
I/flutter ( 8555): #7 BaseChart.draw (package:charts_common/src/chart/common/base_chart.dart:450:9)
I/flutter ( 8555): #8 ChartContainerRenderObject.reconfigure (package:charts_flutter/src/chart_container.dart:170:14)
I/flutter ( 8555): #9 ChartContainer.createRenderObject (package:charts_flutter/src/chart_container.dart:62:49)
I/flutter ( 8555): #10 RenderObjectElement.mount (package:flutter/src/widgets/framework.dart:5491:28)
I/flutter ( 8555): #11 SingleChildRenderObjectElement.mount (package:flutter/src/widgets/framework.dart:6117:11)
I/flutter ( 8555): ... Normal element mounting (7 frames)
I/flutter ( 8555): #18 Element.inflateWidget (package:flutter/src/widgets/framework.dart:3569:14)
I/flutter ( 8555): #19 MultiChildRenderObjectElement.mount (package:flutter/src/widgets/framework.dart:6236:32)
I/flutter ( 8555): ... Normal element mounting (15 frames)
I/flutter ( 8555): #34 Element.inflateWidget (package:flutter/src/widgets/framework.dart:3569:14)
I/flutter ( 8555): #35 MultiChildRenderObjectElement.mount (package:flutter/src/widgets/framework.dart:6236:32)
I/flutter ( 8555): ... Normal element mounting (41 frames)
I/flutter ( 8555): #76 Element.inflateWidget (package:flutter/src/widgets/framework.dart:3569:14)
I/flutter ( 8555): #77 Element.updateChild (package:flutter/src/widgets/framework.dart:3327:18)
I/flutter ( 8555): #78 SliverMultiBoxAdaptorElement.updateChild (package:flutter/src/widgets/sliver.dart:1158:36)
I/flutter ( 8555): #79 SliverMultiBoxAdaptorElement.createChild.<anonymous closure> (package:flutter/src/widgets/sliver.dart:1143:20)
I/flutter ( 8555): #80 BuildOwner.buildScope (package:flutter/src/widgets/framework.dart:2683:19)
I/flutter ( 8555): #81 SliverMultiBoxAdaptorElement.createChild (package:flutter/src/widgets/sliver.dart:1136:11)
I/flutter ( 8555): #82 RenderSliverMultiBoxAdaptor._createOrObtainChild.<anonymous closure> (package:flutter/src/rendering/sliver_multi_box_adaptor.dart:350:23)
I/flutter ( 8555): #83 RenderObject.invokeLayoutCallback.<anonymous closure> (package:flutter/src/rendering/object.dart:1883:59)
I/flutter ( 8555): #84 PipelineOwner._enableMutationsToDirtySubtrees (package:flutter/src/rendering/object.dart:915:15)
I/flutter ( 8555): #85 RenderObject.invokeLayoutCallback (package:flutter/src/rendering/object.dart:1883:14)
I/flutter ( 8555): #86 RenderSliverMultiBoxAdaptor._createOrObtainChild (package:flutter/src/rendering/sliver_multi_box_adaptor.dart:339:5)
I/flutter ( 8555): #87 RenderSliverMultiBoxAdaptor.insertAndLayoutChild (package:flutter/src/rendering/sliver_multi_box_adaptor.dart:485:5)
I/flutter ( 8555): #88 RenderSliverList.performLayout.advance (package:flutter/src/rendering/sliver_list.dart:231:19)
I/flutter ( 8555): #89 RenderSliverList.performLayout (package:flutter/src/rendering/sliver_list.dart:274:19)
I/flutter ( 8555): #90 RenderObject.layout (package:flutter/src/rendering/object.dart:1777:7)
I/flutter ( 8555): #91 RenderSliverEdgeInsetsPadding.performLayout (package:flutter/src/rendering/sliver_padding.dart:132:12)
I/flutter ( 8555): #92 RenderSliverPadding.performLayout (package:flutter/src/rendering/sliver_padding.dart:371:11)
I/flutter ( 8555): #93 RenderObject.layout (package:flutter/src/rendering/object.dart:1777:7)
I/flutter ( 8555): #94 RenderViewportBase.layoutChildSequence (package:flutter/src/rendering/viewport.dart:507:13)
I/flutter ( 8555): #95 RenderShrinkWrappingViewport._attemptLayout (package:flutter/src/rendering/viewport.dart:1904:12)
I/flutter ( 8555): #96 RenderShrinkWrappingViewport.performLayout (package:flutter/src/rendering/viewport.dart:1862:20)
I/flutter ( 8555): #97 RenderObject.layout (package:flutter/src/rendering/object.dart:1777:7)
I/flutter ( 8555): #98 RenderProxyBoxMixin.performLayout (package:flutter/src/rendering/proxy_box.dart:113:14)
I/flutter ( 8555): #99 RenderObject.layout (package:flutter/src/rendering/object.dart:1777:7)
I/flutter ( 8555): #100 RenderProxyBoxMixin.performLayout (package:flutter/src/rendering/proxy_box.dart:113:14)
I/flutter ( 8555): #101 RenderObject.layout (package:flutter/src/rendering/object.dart:1777:7)
I/flutter ( 8555): #102 RenderProxyBoxMixin.performLayout (package:flutter/src/rendering/proxy_box.dart:113:14)
I/flutter ( 8555): #103 RenderObject.layout (package:flutter/src/rendering/object.dart:1777:7)
I/flutter ( 8555): #104 RenderProxyBoxMixin.performLayout (package:flutter/src/rendering/proxy_box.dart:113:14)
I/flutter ( 8555): #105 RenderObject.layout (package:flutter/src/rendering/object.dart:1777:7)
I/flutter ( 8555): #106 RenderProxyBoxMixin.performLayout (package:flutter/src/rendering/proxy_box.dart:113:14)
I/flutter ( 8555): #107 RenderObject.layout (package:flutter/src/rendering/object.dart:1777:7)
I/flutter ( 8555): #108 RenderProxyBoxMixin.performLayout (package:flutter/src/rendering/proxy_box.dart:113:14)
I/flutter ( 8555): #109 RenderObject.layout (package:flutter/src/rendering/object.dart:1777:7)
I/flutter ( 8555): #110 RenderProxyBoxMixin.performLayout (package:flutter/src/rendering/proxy_box.dart:113:14)
I/flutter ( 8555): #111 RenderObject.layout (package:flutter/src/rendering/object.dart:1777:7)
I/flutter ( 8555): #112 RenderProxyBoxMixin.performLayout (package:flutter/src/rendering/proxy_box.dart:113:14)
I/flutter ( 8555): #113 RenderObject.layout (package:flutter/src/rendering/object.dart:1777:7)
I/flutter ( 8555): #114 RenderProxyBoxMixin.performLayout (package:flutter/src/rendering/proxy_box.dart:113:14)
I/flutter ( 8555): #115 RenderObject.layout (package:flutter/src/rendering/object.dart:1777:7)
I/flutter ( 8555): #116 RenderProxyBoxMixin.performLayout (package:flutter/src/rendering/proxy_box.dart:113:14)
I/flutter ( 8555): #117 RenderObject.layout (package:flutter/src/rendering/object.dart:1777:7)
I/flutter ( 8555): #118 RenderProxyBoxMixin.performLayout (package:flutter/src/rendering/proxy_box.dart:113:14)
I/flutter ( 8555): #119 RenderObject.layout (package:flutter/src/rendering/object.dart:1777:7)
I/flutter ( 8555): #120 RenderSliverMultiBoxAdaptor.insertAndLayoutLeadingChild (package:flutter/src/rendering/sliver_multi_box_adaptor.dart:457:19)
I/flutter ( 8555): #121 RenderSliverFixedExtentBoxAdaptor.performLayout (package:flutter/src/rendering/sliver_fixed_extent_list.dart:234:32)
I/flutter ( 8555): #122 RenderObject.layout (package:flutter/src/rendering/object.dart:1777:7)
I/flutter ( 8555): #123 RenderSliverEdgeInsetsPadding.performLayout (package:flutter/src/rendering/sliver_padding.dart:132:12)
I/flutter ( 8555): #124 _RenderSliverFractionalPadding.performLayout (package:flutter/src/widgets/sliver_fill.dart:170:11)
I/flutter ( 8555): #125 RenderObject.layout (package:flutter/src/rendering/object.dart:1777:7)
I/flutter ( 8555): #126 RenderViewportBase.layoutChildSequence (package:flutter/src/rendering/viewport.dart:507:13)
I/flutter ( 8555): #127 RenderViewport._attemptLayout (package:flutter/src/rendering/viewport.dart:1561:12)
I/flutter ( 8555): #128 RenderViewport.performLayout (package:flutter/src/rendering/viewport.dart:1470:20)
I/flutter ( 8555): #129 RenderObject._layoutWithoutResize (package:flutter/src/rendering/object.dart:1634:7)
I/flutter ( 8555): #130 PipelineOwner.flushLayout (package:flutter/src/rendering/object.dart:884:18)
I/flutter ( 8555): #131 RendererBinding.drawFrame (package:flutter/src/rendering/binding.dart:436:19)
I/flutter ( 8555): #132 WidgetsBinding.drawFrame (package:flutter/src/widgets/binding.dart:914:13)
I/flutter ( 8555): #133 RendererBinding._handlePersistentFrameCallback (package:flutter/src/rendering/binding.dart:302:5)
I/flutter ( 8555): #134 SchedulerBinding._invokeFrameCallback (package:flutter/src/scheduler/binding.dart:1117:15)
I/flutter ( 8555): #135 SchedulerBinding.handleDrawFrame (package:flutter/src/scheduler/binding.dart:1055:9)
I/flutter ( 8555): #136 SchedulerBinding._handleDrawFrame (package:flutter/src/scheduler/binding.dart:971:5)
I/flutter ( 8555): (elided 3 frames from dart:async)
I/flutter ( 8555):
I/flutter ( 8555): ════════════════════════════════════════════════════════════════════════════════════════════════════
这是我的代码：
import 'dart:convert';
import 'package:Trimlog/app_localizations.dart';
import 'package:Trimlog/models/boat.dart';
import 'package:Trimlog/models/trim.dart';
import 'package:flutter/material.dart';
import 'package:global_configuration/global_configuration.dart';
import 'package:provider/provider.dart';
import 'package:http/http.dart' as http;
import 'package:charts_flutter/flutter.dart' as charts;
Map<String, dynamic> trimOptions = {};
Map<String, dynamic> trimOption = {};
class AnalyticsGraphs extends StatefulWidget {
final Boat boat;
AnalyticsGraphs(this.boat);
@override
_AnalyticsGraphsState createState() => _AnalyticsGraphsState();
}
class _AnalyticsGraphsState extends State<AnalyticsGraphs> {
bool loading = true; // Enable loading
Future getBoatClassTrimTemplate() async {
String boatClassJson = (await http.get(GlobalConfiguration().getValue("static_api")["boatClasses"] + "/" + widget.boat.boatClass)).body;
trimOptions = await json.decode(boatClassJson)["trimTemplate"];
}
@override
void initState() {
super.initState();
getBoatClassTrimTemplate().then((value) {
setState(() {
loading = false;
});
});
} // Execute once on form open
@override
Widget build(BuildContext context) {
final trims = Provider.of<List<Trim>>(context) ?? null;
List<charts.Series<dynamic, num>> series = [
charts.Series(
measureFn: (dynamic trim, _) => trim.weather["windSpeed"],
domainFn: (dynamic trim, _) => trim.trim[trimOption.keys.first],
colorFn: (dynamic trim, _) {
if (trim.satisfaction < 20) {
return charts.ColorUtil.fromDartColor(Colors.red);
} else if (trim.satisfaction < 40) {
return charts.ColorUtil.fromDartColor(Colors.deepOrange);
} else if (trim.satisfaction < 60) {
return charts.ColorUtil.fromDartColor(Colors.orange);
} else if (trim.satisfaction < 80) {
return charts.ColorUtil.fromDartColor(Colors.lightGreen);
} else if (trim.satisfaction <= 100) {
return charts.ColorUtil.fromDartColor(Colors.green);
}
return charts.ColorUtil.fromDartColor(Colors.grey);
},
id: "windSpeed",
data: trims,
),
];
return Column(
children: [
Padding(
padding: const EdgeInsets.fromLTRB(25.0, 10.0, 25.0, 10.0),
child: DropdownButton<String>(
isExpanded: true,
hint: Text(AppLocalizations.of(context).translate("boats.trimOption")),
elevation: 16,
style: Theme.of(context).textTheme.bodyText1,
value: trimOption.isNotEmpty ? trimOption.keys.first : null,
onChanged: (String val) {
setState(() {
trimOption.clear();
trimOption[val] = trimOptions[val];
});
},
items: trimOptions
.map((key, value) {
return MapEntry(
key,
DropdownMenuItem<String>(
value: key,
child: Text(AppLocalizations.of(context).translate(value["labels"]["label"])),
),
);
})
.values
.toList(),
),
),
trimOption.isNotEmpty
? Padding(
padding: const EdgeInsets.fromLTRB(25.0, 10.0, 25.0, 10.0),
child: SizedBox(
height: 400.0,
child: charts.LineChart(
series,
behaviors: [
new charts.ChartTitle(AppLocalizations.of(context).translate(trimOption.values.first["labels"]["label"]),
behaviorPosition: charts.BehaviorPosition.bottom, titleStyleSpec: charts.TextStyleSpec(fontSize: 11), titleOutsideJustification: charts.OutsideJustification.middleDrawArea),
new charts.ChartTitle(AppLocalizations.of(context).translate("weather.windSpeed") + " (" + AppLocalizations.of(context).translate("units.knots") + ")",
behaviorPosition: charts.BehaviorPosition.start, titleStyleSpec: charts.TextStyleSpec(fontSize: 11), titleOutsideJustification: charts.OutsideJustification.middleDrawArea)
],
defaultRenderer: new charts.LineRendererConfig(
includeLine: true,
includePoints: true,
),
animate: false,
animationDuration: Duration(seconds: 0),
defaultInteractions: false,
),
),
)
: Container(),
],
);
}
}
如果我随后切换到另一个页面，我会收到下一个错误，这会使应用程序完全停止工作。
I/flutter ( 8555): Another exception was thrown: 'package:flutter/src/widgets/framework.dart': Failed assertion: line 3427 pos 12: 'child._parent == this': is not true.
I/flutter ( 8555): Another exception was thrown: A RenderViewport expected a child of type RenderSliver but received a child of type RenderErrorBox.
I/flutter ( 8555): Another exception was thrown: 'package:flutter/src/widgets/framework.dart': Failed assertion: line 4345 pos 14: 'owner._debugCurrentBuildTarget == this': is not true.
您的修剪列表为空。所以你不能创建空数据的图表。你也需要检查一下。您的构建方法将如下所示：
@override
Widget build(BuildContext context) {
final trims = Provider.of<List<Trim>>(context) ?? null;
List<charts.Series<dynamic, num>> series = [];
// Here is important!
if (trims != null) {
series = [
charts.Series(
measureFn: (dynamic trim, _) => trim.weather["windSpeed"],
domainFn: (dynamic trim, _) => trim.trim[trimOption.keys.first],
colorFn: (dynamic trim, _) {
if (trim.satisfaction < 20) {
return charts.ColorUtil.fromDartColor(Colors.red);
} else if (trim.satisfaction < 40) {
return charts.ColorUtil.fromDartColor(Colors.deepOrange);
} else if (trim.satisfaction < 60) {
return charts.ColorUtil.fromDartColor(Colors.orange);
} else if (trim.satisfaction < 80) {
return charts.ColorUtil.fromDartColor(Colors.lightGreen);
} else if (trim.satisfaction <= 100) {
return charts.ColorUtil.fromDartColor(Colors.green);
}
return charts.ColorUtil.fromDartColor(Colors.grey);
},
id: "windSpeed",
data: trims,
),
];
}
return Column(
children: [
Padding(
padding: const EdgeInsets.fromLTRB(25.0, 10.0, 25.0, 10.0),
child: DropdownButton<String>(
isExpanded: true,
hint: Text(
AppLocalizations.of(context).translate("boats.trimOption")),
elevation: 16,
style: Theme.of(context).textTheme.bodyText1,
value: trimOption.isNotEmpty ? trimOption.keys.first : null,
onChanged: (String val) {
setState(() {
trimOption.clear();
trimOption[val] = trimOptions[val];
});
},
items: trimOptions
.map((key, value) {
return MapEntry(
key,
DropdownMenuItem<String>(
value: key,
child: Text(AppLocalizations.of(context)
.translate(value["labels"]["label"])),
),
);
})
.values
.toList(),
),
),
trimOption.isNotEmpty && trims != null // Here is important!
? Padding(
padding: const EdgeInsets.fromLTRB(25.0, 10.0, 25.0, 10.0),
child: SizedBox(
height: 400.0,
child: charts.LineChart(
series,
behaviors: [
new charts.ChartTitle(
AppLocalizations.of(context).translate(
trimOption.values.first["labels"]["label"]),
behaviorPosition: charts.BehaviorPosition.bottom,
titleStyleSpec: charts.TextStyleSpec(fontSize: 11),
titleOutsideJustification:
charts.OutsideJustification.middleDrawArea),
new charts.ChartTitle(
AppLocalizations.of(context)
.translate("weather.windSpeed") +
" (" +
AppLocalizations.of(context)
.translate("units.knots") +
")",
behaviorPosition: charts.BehaviorPosition.start,
titleStyleSpec: charts.TextStyleSpec(fontSize: 11),
titleOutsideJustification:
charts.OutsideJustification.middleDrawArea)
],
defaultRenderer: new charts.LineRendererConfig(
includeLine: true,
includePoints: true,
),
animate: false,
animationDuration: Duration(seconds: 0),
defaultInteractions: false,
),
),
)
: Container(),
],
);