Question

所以我有一个问题，我从列表中删除了一个项目，这给了我一个超出范围的错误，它告诉我在尝试构建我的名片视图时会发生
在手机屏幕上：

 RangeError (index): Invalid value: Not in range 0..1, inclusive: 2

在调试控制台上：

════════ Exception caught by widgets library ═══════════════════════════════════
The following RangeError was thrown building ListViewCard-[<'2'>](dirty, state: _ListViewCard#e102b):
RangeError (index): Invalid value: Not in range 0..1, inclusive: 2

The relevant error-causing widget was
    ListViewCard-[<'2'>] 
package:my_todo_app/main.dart:128
When the exception was thrown, this was the stack
#0      List.[]  (dart:core-patch/growable_array.dart:146:60)
#1      _ListViewCard.build 
package:my_todo_app/main.dart:64
#2      StatefulElement.build 
package:flutter/…/widgets/framework.dart:4619
#3      ComponentElement.performRebuild 
package:flutter/…/widgets/framework.dart:4502
#4      StatefulElement.performRebuild

我不知道我做错了什么，添加项目时，列表可以很好地更新，
这是我的代言人：
一个简单的列表：

List<Todo> todos = [
  Todo("Learn Flutter"),
  Todo("Make Todo App List"),
  Todo("Search for out of range error"),
];

我的列表的卡片视图：

class ListViewCard extends StatefulWidget {
  final int index;
  final Key key;
  final List<Todo> todoList;

  ListViewCard(this.index, this.key, this.todoList);
  @override
  _ListViewCard createState() => _ListViewCard();
}


class _ListViewCard extends State<ListViewCard> {
  @override
  Widget build(BuildContext context) {
    return Card(
        child: ListTile(
        title: Text(widget.todoList[widget.index].text),
        trailing: IconButton(
         icon: Icon(Icons.delete),
          onPressed: () {
            setState(() {
              todos.removeAt(widget.index);
            });
          },
        ),
        onTap: () {},
      ),
     );
  }
}

主场游戏：

class MyHomePage extends StatefulWidget {
  MyHomePage({Key key, this.title}) : super(key: key);
  final String title;
  @override
  _MyHomePageState createState() => _MyHomePageState();
}

class _MyHomePageState extends State<MyHomePage> {
  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text("Todo),
      ),
      body: ReorderableListView(
        onReorder: () {},
        children: List.generate(todos.length, (index) {
          return ListViewCard(index, Key('$index'), todos);
        }),
      ),
      floatingActionButton: FloatingActionButton(
        onPressed: () {
          setState(() {
            todos.insert(todos.length, Todo("New Todo"));
           });
        },
        child: Icon(Icons.add),
      ),
    );
  }
}

Answer 1

您可以在下面复制粘贴运行完整代码
您可以将class MyModel(models.Model): ... def create_zip(self, user, jsondata): filename = "data" + ".zip" with gzip.GzipFile(filename, "w") as fout: fout.write(jsondata.encode("utf-8")) my_model = MyModel.objects.create( user=user, animation_file=filename ) callback传递给refresh()，而ListViewCard会refresh()
代码段

setState

工作演示

完整代码

class _MyHomePageState extends State<MyHomePage> {
...
    void refresh() {
        setState(() {});
      }

class ListViewCard extends StatefulWidget {
  final int index;
  final Key key;
  final List<Todo> todoList;
  VoidCallback callback;

  ListViewCard(this.index, this.key, this.todoList, this.callback);
...  
    onPressed: () {
                todos.removeAt(widget.index);
                widget.callback();

当我尝试从列表中删除项目时，颤振，索引超出范围

1 个答案: