我遇到了“Incorrect use of ParentDataWidget”错误。
并且列表第一次显示时不显示项目。
父级数据小部件Expanded（flex：1）希望将FlexParentData类型的父级数据应用于渲染对象，但该渲染对象已设置为接受不兼容的ParentData类型的父级数据。
通常，这意味着Expanded小部件具有错误的祖先RenderObjectWidget。通常，在Flex小部件内直接放置扩展部件。
有问题的扩展部件当前放置在ConstrainedBox小部件中。
@override
Widget build(BuildContext context) {
return Scaffold(
appBar: AppBar(
actions: <Widget>[
IconButton(
icon: Icon(Icons.shopping_cart),
onPressed: () {},
)
],
backgroundColor: Colors.green,
),
drawer: Drawer(
child: AppDrawer(),
),
body: SingleChildScrollView(
child: ConstrainedBox(
constraints: BoxConstraints(),
child: Column(
children: <Widget>[
Container(
height: 200,
width: double.infinity,
child: HomeSlider(),
),
Padding(
padding: EdgeInsets.only(top: 14.0, left: 8.0, right: 8.0),
child: Text(
AppLocalizations.of(context)
.translate('leatest_producrs'),
style: TextStyle(
color: Theme.of(context).accentColor,
fontSize: 18,
fontWeight: FontWeight.w700)),
),
Container(
margin: EdgeInsets.symmetric(vertical: 8.0),
height: 200.0,
child: Expanded(
child: ListView.builder(
shrinkWrap: true,
scrollDirection: Axis.horizontal,
itemCount: cards.length,
itemBuilder: (BuildContext context, int index) => Card(
child: InkWell(
child: Column(
children: [
Flexible(
child: Container(
height: double.infinity,
width: 120,
decoration: BoxDecoration(
image: DecorationImage(
image: NetworkImage(
cards[index].productImg,
),
fit: BoxFit.fitHeight,
)),
),
),
Container(
width: 150,
padding: EdgeInsets.all(10),
child: Text(cards[index].productName,
style: new TextStyle(fontSize: 12),
softWrap: true),
),
],
),
onTap: () {
Fluttertoast.showToast(
msg: cards[index].productName,
toastLength: Toast.LENGTH_SHORT,
gravity: ToastGravity.BOTTOM,
timeInSecForIosWeb: 1,
backgroundColor: Colors.white70,
textColor: Colors.black,
fontSize: 16.0);
},
),
),
),
),
),
Container(
child: Padding(
padding: EdgeInsets.only(top: 6.0, left: 8.0, right: 8.0),
child: Image(
fit: BoxFit.cover,
image: AssetImage('assets/images/banner-1.jpg'),
),
),
),
Row(
mainAxisAlignment: MainAxisAlignment.spaceBetween,
children: <Widget>[
Padding(
padding: EdgeInsets.only(top: 8.0, left: 8.0, right: 8.0),
child: Text('Featured Products',
style: TextStyle(
color: Theme.of(context).accentColor,
fontSize: 18,
fontWeight: FontWeight.w700)),
),
Padding(
padding: const EdgeInsets.only(
right: 8.0, top: 8.0, left: 8.0),
child: RaisedButton(
color: Theme.of(context).primaryColor,
child: Text('View All',
style: TextStyle(color: Colors.white)),
onPressed: () {
Navigator.pushNamed(context, '/categorise');
}),
)
],
),
Container(
child: GridView.count(
shrinkWrap: true,
physics: NeverScrollableScrollPhysics(),
crossAxisCount: 2,
padding:
EdgeInsets.only(top: 8, left: 6, right: 6, bottom: 12),
children: List.generate(cards.length, (index) {
return Container(
child: Card(
clipBehavior: Clip.antiAlias,
child: InkWell(
onTap: () {
print('Card tapped.');
},
child: Column(
crossAxisAlignment: CrossAxisAlignment.start,
children: <Widget>[
Flexible(
child: Container(
height: double.infinity,
width: double.infinity,
decoration: BoxDecoration(
image: DecorationImage(
image: NetworkImage(
cards[index].productImg,
),
fit: BoxFit.fitHeight,
)),
),
),
ListTile(
title: Text(
cards[index].productName,
style: TextStyle(
fontWeight: FontWeight.w700,
fontSize: 12),
)),
],
),
),
),
);
}),
),
),
Container(
child: Padding(
padding: EdgeInsets.only(
top: 6.0, left: 8.0, right: 8.0, bottom: 10),
child: Image(
fit: BoxFit.cover,
image: AssetImage('assets/images/banner-2.jpg'),
),
),
)
],
),
),
));
错误代码是
══╡ EXCEPTION CAUGHT BY WIDGETS LIBRARY ╞═══════════════════════════════════════════════════════════
The following assertion was thrown while applying parent data.:
Incorrect use of ParentDataWidget.
The ParentDataWidget Expanded(flex: 1) wants to apply ParentData of type FlexParentData to a
RenderObject, which has been set up to accept ParentData of incompatible type ParentData.
Usually, this means that the Expanded widget has the wrong ancestor RenderObjectWidget. Typically,
Expanded widgets are placed directly inside Flex widgets.
The offending Expanded is currently placed inside a ConstrainedBox widget.
The ownership chain for the RenderObject that received the incompatible parent data was:
RepaintBoundary ← NotificationListener<ScrollNotification> ← GlowingOverscrollIndicator ←
Scrollable ← ListView ← Expanded ← ConstrainedBox ← Padding ← Container ← Column ← ⋯
When the exception was thrown, this was the stack:
.
.
.
.
(elided 4 frames from class _RawReceivePortImpl, class _Timer, and dart:async-patch)
════════════════════════════════════════════════════════════════════════════════════════════════════
════════ Exception caught by widgets library ═══════════════════════════════════════════════════════
The following assertion was thrown while applying parent data.:
Incorrect use of ParentDataWidget.
The ParentDataWidget Expanded(flex: 1) wants to apply ParentData of type FlexParentData to a RenderObject, which has been set up to accept ParentData of incompatible type ParentData.
Usually, this means that the Expanded widget has the wrong ancestor RenderObjectWidget. Typically, Expanded widgets are placed directly inside Flex widgets.
The offending Expanded is currently placed inside a ConstrainedBox widget.
The ownership chain for the RenderObject that received the incompatible parent data was:
RepaintBoundary ← NotificationListener<ScrollNotification> ← GlowingOverscrollIndicator ← Scrollable ← ListView ← Expanded ← ConstrainedBox ← Padding ← Container ← Column ← ⋯
When the exception was thrown, this was the stack:
#0 RenderObjectElement._updateParentData.<anonymous closure> (package:flutter/src/widgets/framework.dart:5689:11)
#1 RenderObjectElement._updateParentData (package:flutter/src/widgets/framework.dart:5705:6)
#2 ParentDataElement._applyParentData.applyParentDataToChild (package:flutter/src/widgets/framework.dart:4939:15)
#3 ComponentElement.visitChildren (package:flutter/src/widgets/framework.dart:4600:14)
#4 ParentDataElement._applyParentData.applyParentDataToChild (package:flutter/src/widgets/framework.dart:4942:15)
...
════════════════════════════════════════════════════════════════════════════════════════════════════
