Need Help getting the list of files in a directory and updating it.

[Jake Rener]

I need to get a list of all the files in a particular directory in /sdcard/ and display them on my app. The list needs to updated when a new file is added or deleted from the folder.

I have tried using the Directory method Directory.list() to get a stream of files and used the stream in a StreamBuilder widget but I only get one file repeatedly in the stream.

Here's the code: 

class HomeScreen extends StatefulWidget {
  @override
  _HomeScreenState createState() => _HomeScreenState();
}


class _HomeScreenState extends State<HomeScreen> {
  final booksDir = new Directory('/sdcard/Genesis Reader');
  bool isDirectoryExistent = false;
  List<String> bookPaths = [];
  Stream fileStream;


  final RegExp re = RegExp(r'(?<=Reader\/)(.*)(?=\.epub)');


  @override
  void initState() {
    super.initState();
    getDirStatus();
    // EpubKitty.setConfig("book", "#232931", "vertical", true);
  }


  void getDirStatus() async {
    await booksDir.exists().then((isThere) {
      if (isThere) {
        setState(() {
          isDirectoryExistent = true;
        });
        fileStream = booksDir.list();
      }
    });
  }


  @override
  Widget build(BuildContext context) {
    // print(bookPaths);
    return BaseScaffold(
      subHeading: 'Downloaded Books',
      searchWidget: SearchBar(),
      mainWidget: isDirectoryExistent
          ? StreamBuilder(
              stream: fileStream,
              builder: (context, snapshot) {
                if (snapshot.hasData) {
                  print('from print: ${snapshot.data}');
                  // return Text(snapshot.data.path);
                }
                return CircularProgressIndicator();
              })
          : NoBooks(),
    );
  }
}

What I need is to be able get a stream of files and then use StreamBuilder to list all the files in that directory

[Suzuki Tomohiro]

You may want to use watch rather than list. List cannot handle changes.

https://api.dart.dev/stable/2.7.2/dart-io/FileSystemEntity/watch.html

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[Jake Rener]

Using FileSystemEntity.watch causes : 

ERROR:flutter/lib/ui/ui_dart_state.cc(157)] Unhandled Exception: FileSystemException: File system watching is not supported on this platform, path = ''

I tried this: 

String path = 'path/to/directory';
Directory dir = Directory(path);    
var stream = dir.watch(events: FileSystemEvent.all);
stream.listen((data){
  print(data.path);
});

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[Suzuki Tomohiro]

And your platform is?

> The implementation uses platform-dependent event-based APIs for receiving file-system notifications, thus behavior depends on the platform.

• Windows: Uses ReadDirectoryChangesW. The implementation only supports watching directories. Recursive watching is supported.
• Linux: Uses inotify. The implementation supports watching both files and directories. Recursive watching is not supported. Note: When watching files directly, delete events might not happen as expected.
• OS X: Uses FSEvents. The implementation supports watching both files and directories. Recursive watching is supported.

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[Jake Rener]

My platform is Linux. I am using Kubuntu 18.04 LTS. Just wondering, how is platform relevant to the android emulator or in my case android phone connected externally?

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[Suzuki Tomohiro]

I have zero idea why it does not work. You can use debugger and breakpoint to see what platform your dart VM recognizes the environment before throwing the “watching is not supported” error.

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