最佳答案
Flutter: “ RenderFlex 子元素具有非零的 Flex，但是传入的高度约束是无限的”
我想有一个 ListView内的另一个小部件时，我在一个 Column包装 FutureBuilder，以便有一个简单的 Row。我得到了这个错误:
The following assertion was thrown during performLayout():
I/flutter (13816): RenderFlex children have non-zero flex but incoming height constraints are unbounded.
I/flutter (13816): When a column is in a parent that does not provide a finite height constraint, for example, if it is
I/flutter (13816): in a vertical scrollable, it will try to shrink-wrap its children along the vertical axis. Setting a
I/flutter (13816): flex on a child (e.g. using Expanded) indicates that the child is to expand to fill the remaining
I/flutter (13816): space in the vertical direction.
I/flutter (13816): These two directives are mutually exclusive. If a parent is to shrink-wrap its child, the child
I/flutter (13816): cannot simultaneously expand to fit its parent.
I/flutter (13816): Consider setting mainAxisSize to MainAxisSize.min and using FlexFit.loose fits for the flexible
I/flutter (13816): children (using Flexible rather than Expanded). This will allow the flexible children to size
I/flutter (13816): themselves to less than the infinite remaining space they would otherwise be forced to take, and
I/flutter (13816): then will cause the RenderFlex to shrink-wrap the children rather than expanding to fit the maximum
I/flutter (13816): constraints provided by the parent.
I/flutter (13816): If this message did not help you determine the problem, consider using debugDumpRenderTree():
我的代码:
class ActivityShowTicketReplies extends StatefulWidget {
final Map<String, dynamic> ticketData;
ActivityShowTicketReplies({@required this.ticketData});
@override
State<StatefulWidget> createState() => ActivityShowTicketRepliesState();
}
class ActivityShowTicketRepliesState extends State<ActivityShowTicketReplies> {
TicketsTableData get _ticket => TicketsTableData.fromJson(json.decode(widget.ticketData.values.toList()[0][0].toString()));
@override
Widget build(BuildContext context) {
return ScopedModel(
model: CounterModel(),
child: Directionality(
textDirection: TextDirection.rtl,
child: Scaffold(
body: Column(
children: <Widget>[
Row(
mainAxisAlignment: MainAxisAlignment.center,
crossAxisAlignment: CrossAxisAlignment.center,
children: <Widget>[
Padding(
padding: const EdgeInsets.symmetric(vertical: 20.0),
child: RaisedButton(
color: Colors.indigo,
onPressed: () => BlocProvider.of<AppPagesBloc>(context).dispatch(FragmentNavigateEvent(routeName: FRAGMENT_NEW_TICKET)),
shape: RoundedRectangleBorder(borderRadius: BorderRadius.circular(50.0)),
child: Container(
child: Text(
'new ticket',
style: AppTheme(context).caption().copyWith(color: Colors.white),
),
),
),
),
],
),
FutureBuilder(
future: Provider.of<TicketRepliesTableDao>(context).find(ticketId: _ticket.id),
builder: (context, snapshot) {
if (snapshot.connectionState == ConnectionState.done) {
if (snapshot.hasData) {
final List<TicketRepliesTableData> ticketReplies = snapshot.data;
if (ticketReplies.isNotEmpty) {
return Column(
children: <Widget>[
Card(
clipBehavior: Clip.antiAlias,
color: Colors.grey[50],
margin: EdgeInsets.all(10.0),
child: InkWell(
child: Stack(
children: <Widget>[
Column(
children: <Widget>[
Padding(
padding: const EdgeInsets.symmetric(vertical: 12.0),
child: ListTile(
title: Padding(
padding: const EdgeInsets.symmetric(vertical: 5.0),
child: Text(
'subject',
style: AppTheme(context).caption().copyWith(fontFamily: 'ShabnamBold'),
),
),
subtitle: Text(
_ticket.subject,
style: AppTheme(context).caption(),
),
),
),
Container(
height: 30.0,
margin: EdgeInsets.zero,
width: double.infinity,
color: Colors.grey[200],
child: Row(
mainAxisAlignment: MainAxisAlignment.center,
children: <Widget>[
],
),
),
],
),
Align(
alignment: Alignment.topLeft,
child: Container(
margin: EdgeInsets.only(top: 10.0),
constraints: BoxConstraints(
minWidth: 70.0,
),
height: 20.0,
width: 70.0,
decoration: BoxDecoration(
color: Colors.green[200],
borderRadius: BorderRadius.only(
topRight: Radius.circular(5.0),
bottomRight: Radius.circular(5.0),
)),
child: Center(
child: Text(
'status',
style: AppTheme(context).overLine().copyWith(fontFamily: 'ShabnamBold', color: Colors.black),
),
)),
),
],
),
onTap: () {},
),
),
Expanded(
child: ListView.builder(
itemBuilder: (context, index) {
return Card(
clipBehavior: Clip.antiAlias,
child: Padding(
padding: const EdgeInsets.all(20.0),
child: Column(
mainAxisAlignment: MainAxisAlignment.start,
crossAxisAlignment: CrossAxisAlignment.start,
children: <Widget>[
Row(
children: <Widget>[
Text(
ticketReplies[index].createdAt,
style: AppTheme(context).caption().copyWith(fontFamily: 'ShabnamLight'),
),
],
),
ListTile(
title: Text(ticketReplies[index].reply),
),
],
),
),
);
},
itemCount: ticketReplies.length,
),
),
],
);
} else {
return Center(
child: Text(
'there isn't any reply message',
style: AppTheme(context).caption(),
),
);
}
} else {
return _loader(context, 'no reply');
}
} else
return _loader(context, Strings.pleaseWait);
},
),
],
),
),
),
);
}
Widget _loader(BuildContext context,String message) {
return Center(
child: Column(
mainAxisAlignment: MainAxisAlignment.center,
crossAxisAlignment: CrossAxisAlignment.center,
children: <Widget>[
ColorLoader3(
radius: 25.0,
dotRadius: 5.0,
),
Padding(
padding: const EdgeInsets.all(3.0),
child: Text(
Strings.pleaseWait,
style: AppTheme(context).caption().copyWith(color: Colors.red[900]),
),
),
],
));
}
}
