在dispose（）方法内部调用带有Provider.of（context）的方法会导致“查找已停用的小部件的祖先是不安全的。”

Posted 2023-01-14

当我尝试在State的dispose方法内部调用如下方法时。

  @override
  void dispose() 
    Provider.of<AppProvider>(context, listen: false).close();
    super.dispose();
  

我知道了。

The following assertion was thrown while finalizing the widget tree:
Looking up a deactivated widget's ancestor is unsafe.

At this point the state of the widget's element tree is no longer stable.

To safely refer to a widget's ancestor in its dispose() method, save a reference to the ancestor by calling dependOnInheritedWidgetOfExactType() in the widget's didChangeDependencies() method.

When the exception was thrown, this was the stack
#0      Element._debugCheckStateIsActiveForAncestorLookup.<anonymous closure> 
package:flutter/…/widgets/framework.dart:3508
#1      Element._debugCheckStateIsActiveForAncestorLookup 
package:flutter/…/widgets/framework.dart:3522
#2      Element.getElementForInheritedWidgetOfExactType 
package:flutter/…/widgets/framework.dart:3588
#3      Provider.of 
package:provider/src/provider.dart:219
#4      _MySecondPageState.dispose 
package:test_space/main.dart:138
...

我不确定如何执行此操作To safely refer to a widget's ancestor in its dispose() method, save a reference to the ancestor by calling dependOnInheritedWidgetOfExactType() in the widget's didChangeDependencies() method.我目前正在使用provider: ^4.0.2。

我以前也一样，在dispose（）中使用Provider.of（context），但之前没有此异常。这是因为新的Flutter版本吗？另外，我意识到这里有deactivate（）方法，我应该使用deactivate（）方法而不是dispose（）方法吗？

答案

似乎您正在尝试关闭AppProvider类中定义的内容。如果AppProvider类扩展了ChangeNotifier，则更改通知程序类提供了dispose方法，您可以重写它，然后仅在AppProvider类内调用close函数。