How to open EndDrawer-CodePudding

I'm trying to adapt flutter source code to create a side panel. My code is this :



class _MyHomePageState extends State<MyHomePage> {
  final GlobalKey<ScaffoldState> _scaffoldKey = GlobalKey<ScaffoldState>();
  void _openEndDrawer(){
    _scaffoldKey.currentState!.openEndDrawer();
  }
  void _closeEndDrawer(){
    Navigator.of(context).pop();
  }
  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: HEADER(appBar:new AppBar()),
      drawer:LeftPanel(drawer: new Drawer()),
      endDrawer:  Drawer(
        child: Center(
          child: Column(
            mainAxisAlignment: MainAxisAlignment.center,
            children: <Widget>[
              const Text('This is the Drawer'),
              ElevatedButton(
                onPressed: _closeEndDrawer,
                child: const Text('Close Drawer'),
     ...
      body: Column(
        children: [
          Row(
            mainAxisAlignment: MainAxisAlignment.center,
            children: [
              SectionTitle(title: "Historial"),
              Padding(
                padding: EdgeInsets.fromLTRB(10, 30, 0, 0),
                child: IconButton (
                  icon: Icon(Icons.filter_alt),
                  onPressed: _openEndDrawer,

......

when i click on the button flutter throws this error :

======== Exception caught by gesture ===============================================================
The following _CastError was thrown while handling a gesture:
Null check operator used on a null value

At this point I don't know what to do ..., Im new codding with flutter

CodePudding user response：

You have missed to attach the scaffold key to the scaffold. Due to that accessing currentState giving the error. so make sure to attach the key using key: _scaffoldKey

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      key: _scaffoldKey,
      appBar: AppBar(title: const Text('Drawer Demo')),
      body: (..)
    );
  }

CodePudding user response：

You got an error because your Scaffold key is null

Scaffold( key: _scaffoldKey,...