未为类型“_WebViewTabState”定义方法“_requestDownload”

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I am trying to use flutter_downloader for downloads within InAppWebView. I am trying to use onDownloadStartRequest function of InAppWebViewController to access flutter_downloader download task function, _requestDownload from another file. But I'm getting this error

The method '_requestDownload' isn't defined for the type '_WebViewTabState'. (Documentation) Try correcting the name to the name of an existing method, or defining a method named '_requestDownload'.

How can I use global key to access that method from _WebViewTabState?

webview_tab.dart where I'am trying to access _requestDownload function:

@override
  Widget build(BuildContext context) {
    return Container(
      color: Colors.white,
      child: _buildWebView(),
    );
  }
InAppWebView _buildWebView() {
    var browserModel = Provider.of<BrowserModel>(context, listen: true);
    var settings = browserModel.getSettings();
    var currentWebViewModel = Provider.of<WebViewModel>(context, listen: true);

    if (Util.isAndroid()) {
      InAppWebViewController.setWebContentsDebuggingEnabled(
          settings.debuggingEnabled);
    }
    //----Other code---
    return InAppWebView(
       key: webViewTabStateKey,
      initialUrlRequest: URLRequest(url: widget.webViewModel.url),
      initialSettings: initialSettings,
      onWebViewCreated: (controller) async {//--code}

      onDownloadStartRequest: (controller, downloadStartRequest) async {
        await _requestDownload(TaskInfo()); //ERROR HERE
      },
    ),
}

downloads_page.dart where _requestDownload() function is defined.

class _DownloadsPageState extends State<DownloadsPage> {
  List<TaskInfo>? _tasks;
  late List<ItemHolder> _items;
  late bool _showContent;
  late bool _permissionReady;
  late bool _saveInPublicStorage;
  late String _localPath;
  final ReceivePort _port = ReceivePort();
  //Isolate Code

  //Download Request
  Future<void> _requestDownload(TaskInfo task) async {
    var hasStoragePermission = await Permission.storage.isGranted;
    if (!hasStoragePermission) {
      final status = await Permission.storage.request();
      hasStoragePermission = status.isGranted;
    }
    if (hasStoragePermission) {
      task.taskId = await FlutterDownloader.enqueue(
        url: task.link!,
        headers: {'auth': 'test_for_sql_encoding'},
        savedDir: _localPath,
        saveInPublicStorage: _saveInPublicStorage,
      );
    }
  }
  @override
  Widget build(BuildContext context) {
  }
}
  

Answer 1

It seems you are trying to call a Private method from outside the library where it is defined.

Let's fix that!

---

First remove the prefix _ from the method name that is supposed to be accessed from outside the library where it is defined.

I mean, instead of declaring:

Future<void> _requestDownload(TaskInfo task) async {
...

if you want to be able to call that method from outside you have to define it as:

Future<void> requestDownload(TaskInfo task) async {
...

In Flutter , the prefix _ declares a method as Private , which means you can not access it from outside the library that defines it!

Additionally, to call requestDownload from another library you will have to declare it outside of _DownloadsPageState (at the root level) because _DownloadsPageState is Private itself!

class _DownloadsPageState extends State<DownloadsPage> {
...
}

Future<void> requestDownload(TaskInfo task) async {
...
}

Finally you will need to import the file where the method is defined in the library you want to use it. So, in order to use requestDownload in webview_tab.dart , there you will need to import downloads_page.dart .

---

To learn more on this topic, please visit the Dart's Language tour .