Flutter - 渲染库捕获异常

问题描述 投票：0回答：1

当我尝试单击 ExpansionTile 时，出现此异常。

我正在从 firestore 获取数据。

每个大类中只有几个小类。

那么错误是什么？

除了在 

SubCategoryWidget
中的 
ExpansionTile
添加 
MainCategoryWidget
之外，我还添加了一些文字。

并且工作正常。

请帮我解决这个问题。

这是我的应用程序的屏幕截图。

https://ibb.co/sJ4dVv9

══╡ EXCEPTION CAUGHT BY RENDERING LIBRARY ╞═════════════════════════════════════════════════════════
The following assertion was thrown during performLayout():
RenderFlex children have non-zero flex but incoming height constraints are unbounded.
When a column is in a parent that does not provide a finite height constraint, for example if it is
in a vertical scrollable, it will try to shrink-wrap its children along the vertical axis. Setting a
flex on a child (e.g. using Expanded) indicates that the child is to expand to fill the remaining
space in the vertical direction.
These two directives are mutually exclusive. If a parent is to shrink-wrap its child, the child
cannot simultaneously expand to fit its parent.
Consider setting mainAxisSize to MainAxisSize.min and using FlexFit.loose fits for the flexible
children (using Flexible rather than Expanded). This will allow the flexible children to size
themselves to less than the infinite remaining space they would otherwise be forced to take, and
then will cause the RenderFlex to shrink-wrap the children rather than expanding to fit the maximum
constraints provided by the parent.
If this message did not help you determine the problem, consider using debugDumpRenderTree():
  https://flutter.dev/debugging/#rendering-layer
  http://api.flutter.dev/flutter/rendering/debugDumpRenderTree.html
The affected RenderFlex is:
  RenderFlex#f821c relayoutBoundary=up12 NEEDS-LAYOUT NEEDS-PAINT NEEDS-COMPOSITING-BITS-UPDATE(creator: Column ← Padding ←
  _EffectiveTickerMode ← TickerMode ← Offstage ← Align ← ClipRect ← Column ← Padding ← DecoratedBox ← Container ← AnimatedBuilder ← ⋯, 
  parentData: offset=Offset(0.0, 0.0) (can use size), constraints: BoxConstraints(0.0<=w<=292.7, 0.0<=h<=Infinity), size: MISSING,     
  direction: vertical, mainAxisAlignment: start, mainAxisSize: max, crossAxisAlignment: center, verticalDirection: down)
The creator information is set to:
  Column ← Padding ← _EffectiveTickerMode ← TickerMode ← Offstage ← Align ← ClipRect ← Column ←
  Padding ← DecoratedBox ← Container ← AnimatedBuilder ← ⋯
See also: https://flutter.dev/layout/
If none of the above helps enough to fix this problem, please don't hesitate to file a bug:
  https://github.com/flutter/flutter/issues/new?template=2_bug.md

The relevant error-causing widget was:
  ExpansionTile
  ExpansionTile:file:///E:/Kvu/StudioProjects/shop_app/lib/widgets/category/main_category_widget.dart:28:18

When the exception was thrown, this was the stack:
#0      RenderFlex.performLayout.<anonymous closure> (package:flutter/src/rendering/flex.dart:926:9)
#1      RenderFlex.performLayout (package:flutter/src/rendering/flex.dart:929:6)
#2      RenderObject.layout (package:flutter/src/rendering/object.dart:1915:7)
#3      RenderPadding.performLayout (package:flutter/src/rendering/shifted_box.dart:233:12)
#4      RenderObject.layout (package:flutter/src/rendering/object.dart:1915:7)
#5      RenderProxyBoxMixin.performLayout (package:flutter/src/rendering/proxy_box.dart:116:14)
#6      RenderOffstage.performLayout (package:flutter/src/rendering/proxy_box.dart:3462:13)
#7      RenderObject.layout (package:flutter/src/rendering/object.dart:1915:7)
#8      RenderPositionedBox.performLayout (package:flutter/src/rendering/shifted_box.dart:437:14)
#9      RenderObject.layout (package:flutter/src/rendering/object.dart:1915:7)
#10     RenderProxyBoxMixin.performLayout (package:flutter/src/rendering/proxy_box.dart:116:14)
#11     _RenderCustomClip.performLayout (package:flutter/src/rendering/proxy_box.dart:1376:11)
#12     RenderObject.layout (package:flutter/src/rendering/object.dart:1915:7)
#13     ChildLayoutHelper.layoutChild (package:flutter/src/rendering/layout_helper.dart:56:11)
#14     RenderFlex._computeSizes (package:flutter/src/rendering/flex.dart:829:43)
#15     RenderFlex.performLayout (package:flutter/src/rendering/flex.dart:931:32)
#16     RenderObject.layout (package:flutter/src/rendering/object.dart:1915:7)
#17     RenderPadding.performLayout (package:flutter/src/rendering/shifted_box.dart:233:12)
#18     RenderObject.layout (package:flutter/src/rendering/object.dart:1915:7)
#19     RenderProxyBoxMixin.performLayout (package:flutter/src/rendering/proxy_box.dart:116:14)
#20     RenderObject.layout (package:flutter/src/rendering/object.dart:1915:7)
#21     RenderProxyBoxMixin.performLayout (package:flutter/src/rendering/proxy_box.dart:116:14)
#22     RenderObject.layout (package:flutter/src/rendering/object.dart:1915:7)
#23     RenderProxyBoxMixin.performLayout (package:flutter/src/rendering/proxy_box.dart:116:14)
#24     RenderObject.layout (package:flutter/src/rendering/object.dart:1915:7)
#25     RenderSliverList.performLayout (package:flutter/src/rendering/sliver_list.dart:213:28)
#26     RenderObject.layout (package:flutter/src/rendering/object.dart:1915:7)
#27     RenderSliverEdgeInsetsPadding.performLayout (package:flutter/src/rendering/sliver_padding.dart:137:12)
#28     RenderSliverPadding.performLayout (package:flutter/src/rendering/sliver_padding.dart:371:11)
#29     RenderObject.layout (package:flutter/src/rendering/object.dart:1915:7)
#30     RenderViewportBase.layoutChildSequence (package:flutter/src/rendering/viewport.dart:510:13)
#31     RenderViewport._attemptLayout (package:flutter/src/rendering/viewport.dart:1580:12)
#32     RenderViewport.performLayout (package:flutter/src/rendering/viewport.dart:1489:20)
#33     RenderObject._layoutWithoutResize (package:flutter/src/rendering/object.dart:1757:7)
#34     PipelineOwner.flushLayout (package:flutter/src/rendering/object.dart:887:18)
#35     RendererBinding.drawFrame (package:flutter/src/rendering/binding.dart:504:19)
#36     WidgetsBinding.drawFrame (package:flutter/src/widgets/binding.dart:892:13)
#37     RendererBinding._handlePersistentFrameCallback (package:flutter/src/rendering/binding.dart:370:5)
#38     SchedulerBinding._invokeFrameCallback (package:flutter/src/scheduler/binding.dart:1146:15)
#39     SchedulerBinding.handleDrawFrame (package:flutter/src/scheduler/binding.dart:1083:9)
#40     SchedulerBinding._handleDrawFrame (package:flutter/src/scheduler/binding.dart:997:5)
#44     _invoke (dart:ui/hooks.dart:151:10)
#45     PlatformDispatcher._drawFrame (dart:ui/platform_dispatcher.dart:308:5)
#46     _drawFrame (dart:ui/hooks.dart:115:31)
(elided 3 frames from dart:async)

The following RenderObject was being processed when the exception was fired: RenderFlex#f821c relayoutBoundary=up12 NEEDS-LAYOUT       
NEEDS-PAINT NEEDS-COMPOSITING-BITS-UPDATE:
  creator: Column ← Padding ← _EffectiveTickerMode ← TickerMode ← Offstage ← Align ← ClipRect ← Column
    ← Padding ← DecoratedBox ← Container ← AnimatedBuilder ← ⋯
  parentData: offset=Offset(0.0, 0.0) (can use size)
  constraints: BoxConstraints(0.0<=w<=292.7, 0.0<=h<=Infinity)
  size: MISSING
  direction: vertical
  mainAxisAlignment: start
  mainAxisSize: max
  crossAxisAlignment: center
  verticalDirection: down
This RenderObject had the following descendants (showing up to depth 5):
    child 1: RenderPositionedBox#34444 NEEDS-LAYOUT NEEDS-PAINT NEEDS-COMPOSITING-BITS-UPDATE
      child: RenderSemanticsAnnotations#32acb NEEDS-LAYOUT NEEDS-PAINT NEEDS-COMPOSITING-BITS-UPDATE
        child: RenderConstrainedBox#b0b19 NEEDS-LAYOUT NEEDS-PAINT NEEDS-COMPOSITING-BITS-UPDATE
          child: RenderCustomPaint#b59a9 NEEDS-LAYOUT NEEDS-PAINT
════════════════════════════════════════════════════════════════════════════════════════════════════

Another exception was thrown: RenderBox was not laid out: RenderFlex#f821c relayoutBoundary=up12 NEEDS-PAINT
NEEDS-COMPOSITING-BITS-UPDATE

Another exception was thrown: RenderBox was not laid out: RenderPadding#92988 relayoutBoundary=up11 NEEDS-PAINT
NEEDS-COMPOSITING-BITS-UPDATE

Another exception was thrown: RenderBox was not laid out: RenderOffstage#ccb35 relayoutBoundary=up10 NEEDS-PAINT
NEEDS-COMPOSITING-BITS-UPDATE

Another exception was thrown: RenderBox was not laid out: RenderOffstage#ccb35 relayoutBoundary=up10

Another exception was thrown: 'package:flutter/src/rendering/object.dart': Failed assertion: line 1840 pos 12:
'!_debugDoingThisLayout': is not true.

这是我的代码。

main_category_widget.dart

class MainCategoryWidget extends StatefulWidget {
  final String? selectedCategory;

  const MainCategoryWidget({
    Key? key,
    this.selectedCategory,
  }) : super(key: key);

  @override
  State<MainCategoryWidget> createState() => _MainCategoryWidgetState();
}

class _MainCategoryWidgetState extends State<MainCategoryWidget> {
  @override
  Widget build(BuildContext context) {
    return Expanded(
      child: FirestoreListView<MainCategoryModel>(
        query: mainCategoryCollection(widget.selectedCategory),
        itemBuilder: (context, snapshot) {
          MainCategoryModel mainCategory = snapshot.data();
          return ExpansionTile(
            title: Text(mainCategory.mainCategory),
            children: [
              SubCategoryWidget(
                selectedSubCategory: mainCategory.category,
              ),
            ],
          );
        },
      ),
    );
  }
}

main_category_model.dart

class MainCategoryModel {
  MainCategoryModel({required this.category, required this.mainCategory});

  MainCategoryModel.fromJson(Map<String, Object?> json)
      : this(
          category: json['category']! as String,
          mainCategory: json['mainCategory']! as String,
        );

  final String category;
  final String mainCategory;

  Map<String, Object?> toJson() {
    return {
      'category': category,
      'mainCategory': mainCategory,
    };
  }
}

FirebaseServices _service = FirebaseServices();

mainCategoryCollection(selectedCategory) {
  return _service.mainCategory
      .where('approved', isEqualTo: true)
      .where('category', isEqualTo: selectedCategory)
      .withConverter<MainCategoryModel>(
        fromFirestore: (snapshot, _) =>
            MainCategoryModel.fromJson(snapshot.data()!),
        toFirestore: (movie, _) => movie.toJson(),
      );
}

sub_category_widget.dart

class SubCategoryWidget extends StatelessWidget {
  final String? selectedSubCategory;

  const SubCategoryWidget({
    Key? key,
    this.selectedSubCategory,
  }) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return Expanded(
      child: FirestoreQueryBuilder<SubCategoryModel>(
        query: subCategoryCollection(
          selectedSubCategory: selectedSubCategory,
        ),
        builder: (context, snapshot, _) {
          if (snapshot.isFetching) {
            return const Center(child: CircularProgressIndicator());
          }
          if (snapshot.hasError) {
            return Text('error ${snapshot.error}');
          }

          return GridView.builder(
            shrinkWrap: true,
            itemCount: snapshot.docs.length,
            gridDelegate: const SliverGridDelegateWithFixedCrossAxisCount(
              crossAxisCount: 3,
              childAspectRatio: 1 / 1.1,
            ),
            itemBuilder: (context, index) {
              SubCategoryModel subCategory = snapshot.docs[index].data();
              return Column(
                children: [
                  FittedBox(
                    fit: BoxFit.fill,
                    child: Image.network(subCategory.image),
                  ),
                  Text(subCategory.subCategoryName),
                ],
              );
            },
          );
        },
      ),
    );
  }
}

sub_category_model.dart

class SubCategoryModel {
  SubCategoryModel({
    required this.mainCategoryName,
    required this.subCategoryName,
    required this.image,
  });

  SubCategoryModel.fromJson(Map<String, Object?> json)
      : this(
          mainCategoryName: json['mainCategoryName']! as String,
          subCategoryName: json['subCategoryName']! as String,
          image: json['image']! as String,
        );

  final String mainCategoryName;
  final String subCategoryName;
  final String image;

  Map<String, Object?> toJson() {
    return {
      'mainCategoryName': mainCategoryName,
      'subCategoryName': subCategoryName,
      'image': image,
    };
  }
}

FirebaseServices _service = FirebaseServices();

subCategoryCollection({selectedSubCategory}) {
  return _service.subCategory
      .where('active', isEqualTo: true)
      .where('subCategoryName', isEqualTo: selectedSubCategory)
      .withConverter<SubCategoryModel>(
        fromFirestore: (snapshot, _) =>
            SubCategoryModel.fromJson(snapshot.data()!),
        toFirestore: (movie, _) => movie.toJson(),
      );
}
flutter google-cloud-firestore
1个回答
0
投票

错误的原因是您没有在

sub_category_widget.dart
文件中定义列的高度。

像这样包裹你的专栏

Expanded(
  child: Column(...))

或使用 

SizedBox
或高度如下的容器包裹列

SizedBox(
  height: 100, // preferred height
  child: Column(...),
)
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