Getting Incorrect use of ParentDataWidget error when I use ListView

user_1830228 0
Viewed 14045

In this part of my application I have ListView, when I run app I get this error and I can't resolve that:

Scaffold(
  body: Directionality(
textDirection: TextDirection.rtl,
child: Container(
  child: StreamBuilder(
    stream: globals.database.ticketsDao.getTicketsStream(),
    builder: (BuildContext context, AsyncSnapshot<List<Tickets>> snapshot) {
      if (snapshot.hasData) {
        return Column(
          children: <Widget>[
            Expanded(
              child: ListView.separated(
                  itemBuilder: (context, index) {
                    return ListTile(
                      title: Flexible(
                        child: Text(
                          snapshot.data[index].subject,
                          style: Theme.of(context).textTheme.caption.copyWith(fontFamily: 'IranSansBold'),
                        ),
                      ),
                      subtitle: Text(
                        snapshot.data[index].description,
                        style: Theme.of(context).textTheme.caption.copyWith(fontFamily: 'IranSansLight'),
                      ),
                    );
                  },
                  separatorBuilder: (context, index) {
                    return Divider();
                  },
                  itemCount:  snapshot.data.length),
            ),
          ],
        );
      } else {
        return Container(
            child: Center(
          child: Text(
            Strings.notAnyTickets,),
          ),
        ));
      }
    },
  ),
),
));

error:

══╡ EXCEPTION CAUGHT BY WIDGETS LIBRARY ╞═══════════════════════════════════════════════════════════  
The following assertion was thrown building DefaultTextStyle(debugLabel:
((englishLike subhead  2014).merge(blackMountainView

subhead)).copyWith, inherit: false, color: Color(0xdd000000), family:
Roboto, size: 16.0, weight: 400, baseline: alphabetic, decoration:
TextDecoration.none, softWrap:  wrapping at box width, overflow:
clip):  Incorrect use of ParentDataWidget.

Flexible widgets must be
placed directly inside Flex widgets.  Flexible(no depth, flex: 1,
dirty) has a Flex ancestor, but there are other widgets between them:
 - _ListTile

 - Padding(padding: EdgeInsets(16.0, 0.0, 16.0, 0.0))
 - Semantics(container: false, properties: SemanticsProperties, selected: false, label: null, value:  null, hint: null, hintOverrides:
null)

 - Listener(listeners: [down], behavior: opaque)
 - _GestureSemantics
 - Listener(listeners: <none behavior: translucent)
 - RepaintBoundary
 - IndexedSemantics(index: 0)
 - KeepAlive(keepAlive: false)
 - SliverList(delegate: SliverChildBuilderDelegate#6802e(estimated child count: 19))

 - SliverPadding(padding: EdgeInsets(0.0, 0.0, 0.0, 50.0))
 - Viewport(axisDirection: down, anchor: 0.0, offset: ScrollPositionWithSingleContext#c95ba(offset:
 0.0, range: null..null, viewport: 335.0, ScrollableState, AlwaysScrollableScrollPhysics - ClampingScrollPhysics,
IdleScrollActivity#05a39, ScrollDirection.idle))
 - IgnorePointer-[GlobalKey#a3d1a](ignoring: false, ignoringSemantics: false)

 - Semantics(container: false, properties: SemanticsProperties, label: null, value: null, hint: null,  hintOverrides: null)
 - Listener(listeners: [down], behavior: opaque)
 - _GestureSemantics

 - Listener(listeners: [signal], behavior: deferToChild)
 - _ScrollSemantics-[GlobalKey#7cd1b]
 - RepaintBoundary
 - CustomPaint
 - RepaintBoundary
 - Expanded(flex: 1)  These widgets cannot come between a Flexible and its Flex.  The ownership chain for the parent of the offending
Flexible was:    DefaultTextStyle ← AnimatedDefaultTextStyle ←
_ListTile ← MediaQuery ← Padding ← SafeArea ←  Semantics ← Listener ← _GestureSemantics ← RawGestureDetector ← ⋯
flutter-listview flutter-layout dart flutter
3 Answers

Flexible Widgets must be the direct child of an Expanded or Flex Widget.

In your case, you are using Flexible as a part of a ListTile widget, which is not a suitable parent.

Flexible widgets must be placed directly inside Flex widgets.

Flexible has a Flex ancestor, but there are other widgets between them: - _ListTile

user_121566370

Flexible and Expanded can have row, column or flex as child, but not ListView related widgets.

If you still want the same feel of expanded properties in your widgets, use ConstrainedBox

Ex:

ConstrainedBox(
  constraints: BoxConstraints(minHeight: 50, maxHeight: 500),
  child: ListView.separated(...),
)
user_135777650

For me the issue was using Expanded as a parent widget. I have unknowingly added an Expanded as:

 child: Expanded(
              child: Row(
                children: [
                  const SizedBox(
                    width: 15,
                  ),
                  Expanded().....
                  ])
                )

Then I removed the first Expanded

 child:  Row(
                children: [
                  const SizedBox(
                    width: 15,
                  ),
                  Expanded().....
                  ]
                )

and prob solved!!!
user_154169820
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