如何在扑朔迷离中重建所有网格项目? [英] How to rebuild all grid items in flutter?
问题描述
我有一个 dashboard (以网格表示),应该在长按事件中删除项目(使用 flutter_bloc ),但它会删除最后一项而不是选中项.所有调试打印均显示,该所需元素实际上已从列表中删除,但视图层仍保留该元素.
I have a dashboard, represented by grid, that supposed to delete item on long press event (using flutter_bloc), but it deletes last item instead of selected. All debug prints show, that needed element actually removed from list, but view layer still keeps it.
我的构建功能代码:
Widget build(BuildContext context) {
double pyxelRatio = MediaQuery.of(context).devicePixelRatio;
double width = MediaQuery.of(context).size.width * pyxelRatio;
return BlocProvider(
bloc: _bloc,
child: BlocBuilder<Request, DataState>(
bloc: _bloc,
builder: (context, state) {
if (state is EmptyDataState) {
print("Uninit");
return Center(
child: CircularProgressIndicator(),
);
}
if (state is ErrorDataState) {
print("Error");
return Center(
child: Text('Something went wrong..'),
);
}
if (state is LoadedDataState) {
print("empty: ${state.contracts.isEmpty}");
if (state.contracts.isEmpty) {
return Center(
child: Text('Nothing here!'),
);
} else{
print("items count: ${state.contracts.length}");
print("-------");
for(int i = 0; i < state.contracts.length; i++){
if(state.contracts[i].isFavorite)print("fut:${state.contracts[i].name} id:${state.contracts[i].id}");
}
print("--------");
List<Widget> testList = new List<Widget>();
for(int i = 0; i < state.contracts.length; i++){
if(state.contracts[i].isFavorite) testList.add(
InkResponse(
enableFeedback: true,
onLongPress: (){
showShortToast();
DashBLOC dashBloc = BlocProvider.of<DashBLOC>(context);
dashBloc.dispatch(new UnfavRequest(state.contracts[i].id));
},
onTap: onTap,
child:DashboardCardWidget(state.contracts[i])
)
);
}
return GridView.count(
crossAxisCount: width >= 900 ? 2 : 1,
padding: const EdgeInsets.all(2.0),
children: testList
);
}
}
})
);
}
看起来像网格会自行重建,但不重建其磁贴.如何使用其所有子组件完全更新网格小部件?
Looks like grid rebuilds itself, but don't rebuild its tiles. How can I completely update grid widget with all its subwidgets?
附言:我花了两天时间对其进行修复,请帮助
p.s i've spent two days fixing it, pls help
推荐答案
我认为您应该使用 GridView.builder
构造函数来指定一个生成函数,该函数将根据项目列表中的更改而更新,因此,当您的数据中发生任何更新时, BlocBuilder
将触发您的 GridView
内部的构建功能.
I think you should use a GridView.builder
constructor to specify a build function which will update upon changes in the list of items, so when any update occur in your data the BlocBuilder
will trigger the build function inside yourGridView
.
我希望这个例子更加清楚.
I hope this example makes it more clear.
import 'package:flutter/material.dart';
void main() => runApp(MyApp());
class MyApp extends StatelessWidget {
@override
Widget build(BuildContext context) {
return MaterialApp(
theme: ThemeData(
primarySwatch: Colors.blue,
),
home: Test(),
);
}
}
class Test extends StatefulWidget {
@override
_TestState createState() => _TestState();
}
class _TestState extends State<Test> {
List<int> testList = List<int>();
@override
void initState() {
for (int i = 0; i < 20; i++) {
testList.add(i);
}
super.initState();
}
@override
Widget build(BuildContext context) {
return Scaffold(
appBar: AppBar(),
floatingActionButton: FloatingActionButton(
//Here we can remove an item from the list and using setState
//or BlocBuilder will rebuild the grid with the new list data
onPressed: () => setState(() {testList.removeLast();})
),
body: GridView.builder(
// You must specify the items count of your grid
itemCount: testList.length,
// You must use the GridDelegate to specify row item count
// and spacing between items
gridDelegate: SliverGridDelegateWithFixedCrossAxisCount(
crossAxisCount: 5,
childAspectRatio: 1.0,
crossAxisSpacing: 1.0,
mainAxisSpacing: 1.0,
),
// Here you can build your desired widget which will rebuild
// upon changes using setState or BlocBuilder
itemBuilder: (BuildContext context, int index) {
return Text(
testList[index].toString(),
textScaleFactor: 1.3,
);
},
),
);
}
}
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