The box "contacts" is already open and of type Box<Contact> when trying to access Hive database in flutter

Question

I initialized box database in main as follow

void main() async {
    WidgetsFlutterBinding.ensureInitialized();
    final appDocumentDirectory = await path_provider.getApplicationDocumentsDirectory();
    Hive.init(appDocumentDirectory.path);
    Hive.registerAdapter(ContactAdapter());
    runApp(MyApp());
}

then I open box in the material app by using FutureBuilder plugin as follows:

  FutureBuilder(
      future: Hive.openBox<Contact>('contacts'),
      builder: (context, snapshot) {
        if(snapshot.connectionState == ConnectionState.done){
          if(snapshot.hasError){
            return Text(snapshot.error.toString() );
          }
          return ContactPage();
        } else {
          return Scaffold();
        }
      }
    ),

and inside ContactPage()

I create this:-

  ValueListenableBuilder(
                valueListenable: Hive.box<Contact>('contacts').listenable(),
                builder: (context,Box<Contact> box,_){
                  if(box.values.isEmpty){
                    return Text('data is empty');
                  } else {
                    return ListView.builder(
                      itemCount: box.values.length,
                      itemBuilder: (context,index){
                        var contact = box.getAt(index);
                        return ListTile(
                          title: Text(contact.name),
                          subtitle: Text(contact.age.toString()),
                        );
                      },
                    );
                  }
                },
               )

when I run the application I get the following error

The following HiveError was thrown while handling a gesture:
The box "contacts" is already open and of type Box<Contact>.

and when I tried to use the box without opening it, I got error mean the box is not open.

Do I have to use box without opening it inside ValueListenableBuilder? But then I have to open same box again in the different widget to add data on it.

Answer 1

I'm jumping on this thread because I had a hard time trying to figure out how to deal with the deprecated WatchBoxBuilder while using the resocoder's Hive tutorial, and a google search led me here.

This is what I ended up using:

main.dart:

void main() async {
  if (!kIsWeb) { // <-- I put this here so that I could use Hive in Flutter Web
    final dynamic appDocumentDirectory =
        await path_provider.getApplicationDocumentsDirectory();
    Hive.init(appDocumentDirectory.path as String);
  }
  Hive.registerAdapter(ContactAdapter());

  runApp(child: MyApp());
}

and then ContactPage() (note: it's the same as OP's):

Widget _buildListView() {
  return ValueListenableBuilder(
    valueListenable: Hive.box<Contact>('contacts').listenable(),
    builder: (context, Box<Contact> box, _) {
      if (box.values.isEmpty) {
        return Text('data is empty');
      } else {
        return ListView.builder(
          itemCount: box.values.length,
          itemBuilder: (context, index) {
            var contact = box.getAt(index);
            return ListTile(
              title: Text(contact.name),
              subtitle: Text(contact.age.toString()),
            );
          },
        );
      }
    },
  );
}

Answer 2

Its a simple explanation actually:
1. It only occurs when your box has a generic type like
Hive.openBox<User>('users')

2. So once you call Hive.box('users') without specifying the generic type this error occurs.

THATS EVERYTHING.

SOLUTION
Hive.box<User>('users') at each call :)