键盘打开时关闭EndDrawer抛出Widget已卸载异常求助

当键盘处于打开状态时关闭EndDrawer会触发如下断言异常，键盘未聚焦时无此问题。抽屉内包含SearchField组件，本不应出现该错误。

异常信息 #

======== Exception caught by widgets library =======================================================
The following assertion was thrown building StreamBuilder<List<SearchFieldListItem<dynamic>?>?>(dirty, state: _StreamBuilderBaseState<List<SearchFieldListItem<dynamic>?>?, AsyncSnapshot<List<SearchFieldListItem<dynamic>?>?>>#75ea8):
This widget has been unmounted, so the State no longer has a context (and should be considered defunct). 

相关代码 #

appBar: AppBar(title: Text('XYZ')),
endDrawer: Drawer(
  child: ListView(
    children: [
      Padding(
        padding: EdgeInsets.all(10),
        child: SizedBox(
          child: const DrawerHeader(
            child: Text('Filter'),
          ),
        ),
      ),
      Padding(
        padding: EdgeInsets.all(10),
        child: Container(
          child: SearchField<Model>(
            onSuggestionTap: (buyerValue) {},
          ),
        ),
      ),
    ],
  ),
),
body: Container(),

解决方案 #

方法1：主动取消SearchField的焦点 #

通过给SearchField绑定FocusNode，在抽屉关闭时主动取消焦点，避免键盘未收起导致组件状态异常更新：

1. 定义FocusNode：

   final FocusNode _searchFocusNode = FocusNode();
   

2. 给SearchField绑定FocusNode：

   SearchField<Model>(
     focusNode: _searchFocusNode,
     onSuggestionTap: (buyerValue) {},
   ),
   

3. 在Scaffold中监听抽屉状态，关闭时取消焦点：

   Scaffold(
     // ...其他配置项
     onEndDrawerChanged: (isOpen) {
       if (!isOpen) {
         _searchFocusNode.unfocus();
       }
     },
     endDrawer: // ...你的抽屉代码
   )
   

方法2：在StreamBuilder中判断组件挂载状态 #

如果可以修改SearchField内部的StreamBuilder逻辑，在构建UI前先判断组件是否仍处于挂载状态，避免卸载后触发状态更新：

StreamBuilder<List<SearchFieldListItem<dynamic>?>?>(
  stream: // 原数据流配置
  builder: (context, snapshot) {
    // 先校验组件挂载状态
    if (!context.mounted) return const SizedBox.shrink();
    // 原有的UI构建逻辑
  },
)

方法3：关闭抽屉前强制隐藏键盘 #

在触发抽屉关闭的操作前，先主动隐藏键盘，确保组件状态稳定后再关闭抽屉：

// 示例：关闭按钮的点击事件
onPressed: () {
  FocusManager.instance.primaryFocus?.unfocus();
  Navigator.of(context).pop();
}

内容的提问来源于stack exchange，提问作者Neev Shah