Question

要在其dispose()方法中安全地引用窗口小部件的祖先，请通过在窗口小部件的dependOnInheritedWidgetOfExactType()方法中调用didChangeDependencies()来保存对祖先的引用。

我如何保存参考，我不知道，我是新手。

这是我的示例代码：图像井井有条 First

  class QuestionFeed extends StatefulWidget {
 final  FirebaseUser loggedInUser;
QuestionFeed({    this.loggedInUser   });

 @override
 _QuestionFeedState createState() => _QuestionFeedState();
}

  class _QuestionFeedState extends State<QuestionFeed> {
    List<Widget> questions;
    List<String> followingsList=[];
   bool x;
   final _scaffoldKey=GlobalKey<ScaffoldState>();

retrieveTimeLine()async{
QuerySnapshot querySnapshot =await 
questionsFeedReference.orderBy("timeStamp",descending: 
true).getDocuments();
setState(() {
  List<Widget> allQuestions=querySnapshot.documents.where((element) {
    if(element["type"]=="question" ){
      x=true;
      return true;
    }
    else if(element["type"]=="answer"){
      x=false;
      return true;
    }
    else{
      return false;
    }
  }).map((document)=>x?Question.fromDocument(document):
  StreamBuilder<DocumentSnapshot>(
    stream: answersReference.document("038281b3-3842-4ea9-b4d8- 
 3155a571826e").snapshots(),
    builder: (context, snapshot) {
      if (!snapshot.hasData) {
        return Center(
          child: CircularProgressIndicator(
            backgroundColor: Colors.lightBlueAccent,
          ),
        );
      }
      NotusDocument _document;
      ZefyrController _zefyrController;
      FocusNode _focusNode;
      final messages = snapshot.data;
      final messageText = messages.data['answer'];
      _document =NotusDocument.fromJson( jsonDecode(messageText));
      _zefyrController = ZefyrController(_document);
      _focusNode=FocusNode();
      return  Container(
        height: 400,
        child: ZefyrScaffold(

          child: ZefyrEditor(
            padding: EdgeInsets.all(16),
            controller: _zefyrController,
            mode: ZefyrMode.view,
            focusNode: _focusNode,
            imageDelegate: MyAppZefyrImageDelegate(),
            physics: NeverScrollableScrollPhysics(),
          ),
        ),
      );

    },
  )

  ).toList();
  this.questions=allQuestions;
});
}
 @override
 void initState() {
// TODO: implement initState
super.initState();
retrieveTimeLine();

 }

  createUserTimeLine(){
   retrieveTimeLine();
  if(questions==null){
  return circularProgress();
 }
else{
  return ListView(children: questions,);
}
}

@override
Widget build(context) {
return Scaffold(
  key: _scaffoldKey,
  appBar: header(
    context,
    isAppTitle: true,
  ),
  body: RefreshIndicator(
  child: createUserTimeLine(),onRefresh()=>retrieveTimeLine(),),
   );
}
}

我正在使用Zefyr Editor，然后检索其数据并将其显示在Container中

查找停用的窗口小部件的祖先是不安全的。如何保存参考？

0 个答案: