Question

我无法从孩子那里更新父状态。子窗口小部件具有名为“ onDragEnd”的回调，一旦完成对网格单元的拖放操作，就会调用该回调。这时，父级（网格）应根据新排序项重建UI，但是什么也没有发生。如果我在'setState（）'之前设置断点，则'elems'属性包含正确排序的正确项目。即使替换整个列表，UI也不会更新。有什么建议么？我想念什么？

class _CustomGridState extends State<CustomGrid> { 

    List<Pack> elems;

    _CustomGridState(this.elems);

    @override
    Widget build(BuildContext context) {
         return GridView.count(
                crossAxisCount: 3,
                children: this
                  .elems
                  .map((pack) => PackFingernail(pack: pack,

                       onDragEnd: (Pack source, Pack target) {

                            var sourceIndex = this.elems.indexWhere((p) => p.id == source.id);
                            var targetIndex = this.elems.indexWhere((p) => p.id == target.id);

                            this.elems.removeAt(sourceIndex);
                            this.elems.insert(targetIndex, source);

                            setState(() {}); // Not working <-----
                       })

                   ).toList()
               );
   }
 }

Answer 1

尝试为您的public function index() { $users = DB::select('SELECT * FROM users'); dd($users); }添加密钥

PackFingernail

// constructor PackFingernail(..., {Key key}): super(key:key) // in gridview .map((pack) => PackFingernail(pack: pack, onDragEnd: (Pack source, Pack target) { ... }, key: Key(pack.id.toString())) ).toList()可以帮助重建Key

Flutter-从孩子更新父状态

1 个答案: