I wrote a StreamProvider that I listen to right after startup to get all the information about a potentially logged in user. If there is no user, so the outcome would be null, the listener stays in loading state, so I decided to send back a default value of an empty user to let me know that the loading is done.
I had to do this, because Hive's watch() method is only triggered when data changes, which it does not at startup.
So after that, I want the watch() method to do its job, but the problem with that, are the following scenarios:
At startup: No user - Inserting a user -> watch method is triggered -> I get the inserted users data -> Deleting the logged in user -> watch method is not triggered.
At startup: Full user - Deleting the user -> watch method is triggered -> I get an empty user -> Inserting a user -> watch method is not triggered.
After some time I found out that I can make use of all CRUD operations as often as I want to and the Hive's box does what it should do, but the watch() method is not triggered anymore after it got triggered once.
The Streamprovider(s):
final localUsersBoxFutureProvider = FutureProvider<Box>((ref) async {
final usersBox = await Hive.openBox('users');
return usersBox;
});
final localUserStreamProvider = StreamProvider<User>((ref) async* {
final usersBox = await ref.watch(localUsersBoxFutureProvider.future);
yield* Stream.value(usersBox.get(0, defaultValue: User()));
yield* usersBox.watch(key: 0).map((usersBoxEvent) {
return usersBoxEvent.value == null ? User() : usersBoxEvent.value as User;
});
});
The Listener:
return localUserStream.when(
data: (data) {
if (data.name == null) {
print('Emitted data is an empty user');
} else {
print('Emitted data is a full user');
}
return Container(color: Colors.blue, child: Center(child: Row(children: [
RawMaterialButton(
onPressed: () async {
final globalResponse = await globalDatabaseService.signup({
'email' : '[email protected]',
'password' : 'password',
'name' : 'My Name'
});
Map<String, dynamic> jsonString = jsonDecode(globalResponse.bodyString);
await localDatabaseService.insertUser(User.fromJSON(jsonString));
},
child: Text('Insert'),
),
RawMaterialButton(
onPressed: () async {
await localDatabaseService.removeUser();
},
child: Text('Delete'),
)
])));
},
loading: () {
return Container(color: Colors.yellow);
},
error: (e, s) {
return Container(color: Colors.red);
}
);
The CRUD methods:
Future<void> insertUser(User user) async {
Box usersBox = await Hive.openBox('users');
await usersBox.put(0, user);
await usersBox.close();
}
Future<User> readUser() async {
Box usersBox = await Hive.openBox('users');
User user = usersBox.get(0) as User;
await usersBox.close();
return user;
}
Future<void> removeUser() async {
Box usersBox = await Hive.openBox('users');
await usersBox.delete(0);
await usersBox.close();
}
Any idea how I can tell the StreamProvider that the watch() method should be kept alive, even if one value already got emitted?
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