嵌套可重新排序的列表？

Posted 2023-02-23

【中文标题】嵌套可重新排序的列表？

【英文标题】：Nesting reorderable lists?

【发布时间】：2019-11-05 15:42:08

【问题描述】：

我有一个由ListTiles 和ExpansionTiles 组成的ReorderableList，并且希望ExpansionTiles 的子代可以重新排序。孩子是递归的，因为它们也是ListTiles 和ExpansionTiles 的混合体。这是我当前的代码：

Widget _buildList() 
  return Scrollbar(
    child: ReorderableListView(
      padding: const EdgeInsets.all(25),
      children: topLevelOrder.map<Widget>(_buildItem).toList(),
      onReorder: (oldIndex, newIndex) 
      // ...
      ,
    ),
  );


Widget _buildItem(String id) 
  Map item = data[id];
  List children = item["children"];
  if (children.length > 0) 
    List<Widget> childWidgets = [];
    for (var child in children)
      childWidgets.add(_buildItem(child));
    return ExpansionTile(
      key: Key(id),
      initiallyExpanded: true,
      title: Text(id),
      children: [
        ReorderableListView(
          children: childWidgets,
          onReorder: (oldIndex, newIndex) 
            // ...
          ,
        )
      ],
    );
  
  return ListTile(
    key: Key(id),
    title: Text(id)
  );

其中data 是测试数据的硬编码字典（只有两层深）。但是，这会引发 BoxConstraints forces an infinite height 错误。如何解决此问题或以其他方式实现嵌套的可重新排序列表？

【问题讨论】：

这个有什么更新吗？

【参考方案1】：

我尝试过类似的事情，但我只是没有看到它以这种方式工作，（也许它工作，我不确定），相反，我提供了多个 ReorderableListView（也可以是 ReorderableListView.builder）小部件的解决方案嵌套在 SingleChildScrollView 小部件中，也可以嵌套在其他小部件中，如您从示例中看到的那样。在我看来，这也适用于操作问题

玩得开心飞来飞去

导入'package:flutter/material.dart';

/// This is the main application widget.

/// This is the stateful widget that the main application instantiates.
class MyStatefulWidget extends StatefulWidget 
  const MyStatefulWidget(Key? key) : super(key: key);

  @override
  State<MyStatefulWidget> createState() => _MyStatefulWidgetState();


/// This is the private State class that goes with MyStatefulWidget.
class _MyStatefulWidgetState extends State<MyStatefulWidget> 
  final List<int> _items = List<int>.generate(10, (int index) => index);
  final List<int> _items2 = List<int>.generate(15, (int index2) => index2);

  @override
  Widget build(BuildContext context) 
    final ColorScheme colorScheme = Theme.of(context).colorScheme;
    final Color oddItemColor = colorScheme.primary.withOpacity(0.05);
    final Color evenItemColor = colorScheme.primary.withOpacity(0.15);
    int index = 0;
    int index2 = 0;

    return Scaffold(
      appBar: AppBar(
        title: Text('Example'),
      ),
      body: SingleChildScrollView(
        child: Column(
          children: <Widget>[
            ListTile(title: Text('test 1')),
            ListTile(title: Text('test 2')),
            ReorderableListView(
              physics: ClampingScrollPhysics(),
              shrinkWrap: true,
              padding: const EdgeInsets.symmetric(horizontal: 40),
              children: <Widget>[
                for (index = 0; index < _items.length; index++)
                  ListTile(
                    key: Key('$index'),
                    tileColor:
                        _items[index].isOdd ? oddItemColor : evenItemColor,
                    title: Text('Item $_items[index]'),
                  ),
              ],
              onReorder: (int oldIndex, int newIndex) 
                setState(() 
                  if (oldIndex < newIndex) 
                    newIndex -= 1;
                  
                  final int item = _items.removeAt(oldIndex);
                  _items.insert(newIndex, item);
                );
              ,
            ),
            ListTile(title: Text('test 3')),
            ListTile(title: Text('test 4')),
            ReorderableListView(
              physics: ClampingScrollPhysics(),
              shrinkWrap: true,
              padding: const EdgeInsets.symmetric(horizontal: 40),
              children: <Widget>[
                for (index2 = 0; index2 < _items2.length; index2++)
                  ListTile(
                    key: Key('$index2'),
                    tileColor:
                        _items2[index2].isOdd ? oddItemColor : evenItemColor,
                    title: Text('Item $_items2[index2]'),
                  ),
              ],
              onReorder: (int oldIndex2, int newIndex2) 
                setState(() 
                  if (oldIndex2 < newIndex2) 
                    newIndex2 -= 1;
                  
                  final int item = _items2.removeAt(oldIndex2);
                  _items2.insert(newIndex2, item);
                );
              ,
            ),
            ListTile(title: Text('test 5')),
            ListTile(title: Text('test 6')),
          ],
        ),
      ),
    );