有多个英雄在子树中共享相同的标记

Question

我试图通过路线从一个屏幕导航到另一个屏幕.当我点击页面按钮移动到提供的路线时,我收到错误

I/flutter ( 8790): Another exception was thrown: There are multiple heroes that share the same tag within a subtree.

这是代码:

路线:

 <String, WidgetBuilder>{
    '/first':(BuildContext context) =>NavigatorOne() ,
    '/second':(BuildContext context) =>NavigatorTwo(),
    '/third':(BuildContext context) =>NavigatorThree(),

  },

Navigator.of(context).pushNamed('/first');
Navigator.of(context).pushNamed('/second');
Navigator.of(context).pushNamed('/third');

class NavigatorOne extends StatefulWidget {
  @override
  _NavigatorOneState createState() =>  _NavigatorOneState();
}

class _NavigatorOneState extends State<NavigatorOne> {
  @override
  Widget build(BuildContext context) {
    return Scaffold(

      appBar: AppBar(),
      body: Container(
      color: Colors.green,
      child: RaisedButton(child: Text(' one 1'),onPressed: (){
        Navigator.of(context).pushNamed('/second');
      },),
    ),
    ); 
  }
}

而错误:

??? EXCEPTION CAUGHT BY SCHEDULER LIBRARY ?????????????????????????????????????????????????????????? I/flutter (21786): The following assertion was thrown during a scheduler callback: I/flutter (21786): There are multiple heroes that share the same tag within a subtree. I/flutter (21786): Within each subtree for which heroes are to be animated (typically a PageRoute subtree), each Hero I/flutter (21786): must have a unique non-null tag. I/flutter (21786): In this case, multiple heroes had the following tag: <default FloatingActionButton tag>

我该如何解决这个问题？

Answer 1

之前我遇到过这个问题,因为我在一个屏幕上有两个FloatingAction按钮,我必须为每个FLoatingActionButton添加一个heroTag属性+值,以便错误消失.

例:

new FloatingActionButton(
    heroTag: "btn1",
    ...
)

new FloatingActionButton(
    heroTag: "btn2",
    ...
)

从您提供的示例代码看来,您似乎没有FloatingActionButton,但从错误中它似乎引用它:

I/flutter(21786):在这种情况下,多个英雄有以下标记:默认FloatingActionButton标记

也许您在导航到的页面上使用它然后触发了错误.

无论如何,希望能帮到某个人.

Answer 2

你可以设置一个唯一的 id 或者只设置 null：

new FloatingActionButton(
heroTag: null,
...
)

Answer 3

只为未来的读者：

在欣赏到@ m.vincent评论，什么导致这个错误对我来说，我用英雄里面SliverChildBuilderDelegate哪些（显然）有一个索引，所以我用的指标有像标签'tag$index'这样

SliverChildBuilderDelegate(
    (BuildContext context, int index) {
      return Column(
          mainAxisSize: MainAxisSize.min,
          children: <Widget>[
            Hero(
              tag: 'tagImage$index',
              child: Image.asset(
                'image source here',
              ),
            ),

注意：这可能发生在任何具有索引创建子项的小部件上，例如 ListView.Builder

Answer 4

还有另一种方法：

FloatingActionButton(
    heroTag: UniqueKey(),
    ....  
)

https://api.flutter.dev/flutter/foundation/UniqueKey-class.html

UniqueKey() 创建一个仅等于其自身的密钥。

Answer 5

对我来说，仅仅添加一个 uniqueheroTag到 myFloatingActionButtons是行不通的。我最终将其包装heroTag在一个Text小部件中，这为我解决了问题。

new FloatingActionButton(
    heroTag: Text("btn1"),
    ...
)

new FloatingActionButton(
    heroTag: Text("btn2"),
    ...
)