ReorderableListView：异常：BoxConstraints 强制无限高度

Question

TL;DR - 如何在ReorderableListView 中实现shrinkWrap = true？

我试图以Column<-Container 作为父级创建ReoderableListView，发生了这个错误。

I/flutter (32618): The following assertion was thrown during performLayout():
I/flutter (32618): BoxConstraints forces an infinite height.


I/flutter (32618): The following RenderObject was being processed when the exception was fired: RenderStack#23840 relayoutBoundary=up17 NEEDS-LAYOUT NEEDS-PAINT NEEDS-COMPOSITING-BITS-UPDATE:
I/flutter (32618):   creator: Stack ← _Theatre ← Overlay-[GlobalKey#dc153 ReorderableListView overlay key] ←
I/flutter (32618):     ReorderableListView ← StreamBuilder<QuerySnapshot> ← Column ← Padding ← Padding ← Container ←
I/flutter (32618):     BoardCard ← Column ← _SingleChildViewport ← ⋯
I/flutter (32618):   parentData: not positioned; offset=Offset(0.0, 0.0) (can use size)
I/flutter (32618):   constraints: BoxConstraints(0.0<=w<=328.0, 0.0<=h<=Infinity)
I/flutter (32618):   size: MISSING
I/flutter (32618):   alignment: AlignmentDirectional.topStart
I/flutter (32618):   textDirection: ltr
I/flutter (32618):   fit: expand
I/flutter (32618):   overflow: clip
I/flutter (32618): This This RenderObject had the following child:
I/flutter (32618):     child 1: _RenderLayoutBuilder#55d3d NEEDS-LAYOUT NEEDS-PAINT

如果它是ListView，使用shrinkWrap = true 很容易解决此问题，但ReorderableListView 没有此属性。

这里是代码

@override
  Widget build(BuildContext context) {
    final _listTitleStyle =
        TextStyle(fontSize: 20, fontWeight: FontWeight.w500);
    final _listSubTitleStyle = TextStyle(
      fontSize: 14,
      fontWeight: FontWeight.w400,
      color: Color(0xff7D7373),
    );
    return Container(
      padding: EdgeInsets.all(8),
      margin: EdgeInsets.all(8),
      child: Column(
        children: <Widget>[
          Container(
            child: Row(
              children: <Widget>[
                Expanded(
                  child: Row(
                    textBaseline: TextBaseline.alphabetic,
                    crossAxisAlignment: CrossAxisAlignment.baseline,
                    children: <Widget>[
                      Text(
                        widget.cardTitle,
                        style: _listTitleStyle,
                      ),
                      SizedBox(
                        width: 2,
                      ),
                      Text(
                        widget.cardSubTitle,
                        style: _listSubTitleStyle,
                      ),
                    ],
                  ),
                ),
                Icon(Icons.keyboard_arrow_down),
              ],
            ),
          ),
          SizedBox(
            height: 8,
          ),
          StreamBuilder<QuerySnapshot>(
              stream: widget.query,
              builder: (context, snapshot) {
                if (!snapshot.hasData) return LinearProgressIndicator();
                return _buildList(context, snapshot.data.documents);
              }),
        ],
      ),
    );
  }

  Widget _buildList(BuildContext context, List<DocumentSnapshot> snapshot) {
    snapshot.forEach((snap) {
      print("debug 1 ${snap.data}");
      print(TodoItem.fromSnapshot(snap, snap.reference).toString());
    });
    return ReorderableListView(
      onReorder: (oldIndex, newIndex){},
      children: snapshot
          .map((data) => TodoTile(TodoItem.fromSnapshot(data, data.reference), key: UniqueKey(),))
          .toList(),
    );
  }

Answer 1

我已经通过用包flutter_reorderable_list 替换ReorderableListView 解决了这个问题，它接受一个孩子（Widget），不像ReorderableListView 接受孩子（列表）

它的实现有点复杂。您可以查看example 以了解正确实现它。

Answer 2

我同意 Abdulrahman Falyoun 的观点。您只需要动态调整高度并根据列表中的项目数进行调整。

 Container(
      height: (list.length * 40).toDouble(),
      padding: const EdgeInsets.all(10),
      child: ReorderableListView(
        children: list.map((item) {
          return getItem(item);
        }).toList(),
        onReorder: _onReorder,
      ),
    )

或者如果它在一个列中，那么用Expanded()包裹它

Answer 3

使用 Columnto listview 并应用 shrinkWrap = true

@override
  Widget build(BuildContext context) {
    final _listTitleStyle =
        TextStyle(fontSize: 20, fontWeight: FontWeight.w500);
    final _listSubTitleStyle = TextStyle(
      fontSize: 14,
      fontWeight: FontWeight.w400,
      color: Color(0xff7D7373),
    );
    return Container(
      padding: EdgeInsets.all(8),
      margin: EdgeInsets.all(8),
      child: Listview(
        shrinkWrap = true
        children: <Widget>[
          Container(
            child: Row(
              children: <Widget>[
                Expanded(
                  child: Row(
                    textBaseline: TextBaseline.alphabetic,
                    crossAxisAlignment: CrossAxisAlignment.baseline,
                    children: <Widget>[
                      Text(
                        widget.cardTitle,
                        style: _listTitleStyle,
                      ),
                      SizedBox(
                        width: 2,
                      ),
                      Text(
                        widget.cardSubTitle,
                        style: _listSubTitleStyle,
                      ),
                    ],
                  ),
                ),
                Icon(Icons.keyboard_arrow_down),
              ],
            ),
          ),
          SizedBox(
            height: 8,
          ),
          StreamBuilder<QuerySnapshot>(
              stream: widget.query,
              builder: (context, snapshot) {
                if (!snapshot.hasData) return LinearProgressIndicator();
                return _buildList(context, snapshot.data.documents);
              }),
        ],
      ),
    );
  }

  Widget _buildList(BuildContext context, List<DocumentSnapshot> snapshot) {
    snapshot.forEach((snap) {
      print("debug 1 ${snap.data}");
      print(TodoItem.fromSnapshot(snap, snap.reference).toString());
    });
    return ReorderableListView(
      onReorder: (oldIndex, newIndex){},
      children: snapshot
          .map((data) => TodoTile(TodoItem.fromSnapshot(data, data.reference), key: UniqueKey(),))
          .toList(),
    );
  }