In SearchData class any change in result update the UI but any change in history, is not updating the UI, even tho the implemenation of both is same. I'm calling notify for both of em.
Below is the class code
class SearchData<T> {
List<R> copyList<R>(List<R>? list) => List.from(list ?? []);
SearchData(this.notify, this.historyKey) {
_loadHistory();
}
final void Function([VoidCallback? action]) notify;
final String historyKey;
int page = 1;
List<T>? _result;
List<T>? get result => _result;
// search history
List<String> _history = [];
List<String> get history => _history;
void _loadHistory() async {
final data = await DataBox(historyKey).readStringList();
if (kDebugMode) {
print('hello loaded history = $data');
}
if (data != null) notify(() => _history = copyList(data));
}
void updateSearchResult(String query, List<T>? newResult, bool isLoadMore) {
if (newResult == null) return;
notify(() {
if (isLoadMore) {
_result = copyList(result)..addAll(newResult);
} else {
_result = newResult;
}
});
// save local history of search
if (!_history.contains(query)) {
_history.add(query);
DataBox(historyKey).writeStringList(history);
}
}
}
I tried the workoaroud of creating new instance of list, so notify listner could update the UI.
Related
I have a StateNotifierProvider that calls an async function which loads some images from the internal storage and adds them to the AsyncValue data:
//Provider declaration
final paginationImagesProvider = StateNotifierProvider.autoDispose<PaginationNotifier, AsyncValue<List<Uint8List?>>>((ref) {
return PaginationNotifier(folderId: ref.watch(localStorageSelectedFolderProvider), itemsPerBatch: 100, ref: ref);
});
//Actual class with AsyncValue as State
class PaginationNotifier extends StateNotifier<AsyncValue<List<Uint8List?>>> {
final int itemsPerBatch;
final String folderId;
final Ref ref;
int _numberOfItemsInFolder = 0;
bool _alreadyFetching = false;
bool _hasMoreItems = true;
PaginationNotifier({required this.itemsPerBatch, required this.folderId, required this.ref}) : super(const AsyncValue.loading()) {
log("PaginationNotifier created with folderId: $folderId, itemsPerBatch: $itemsPerBatch");
init();
}
final List<Uint8List?> _items = [];
void init() {
if (_items.isEmpty) {
log("fetchingFirstBatch");
_fetchFirstBatch();
}
}
Future<List<Uint8List?>> _fetchNextItems() async {
List<AssetEntity> images = (await (await PhotoManager.getAssetPathList())
.firstWhere((element) => element.id == folderId)
.getAssetListRange(start: _items.length, end: _items.length + itemsPerBatch));
List<Uint8List?> newItems = [];
for (AssetEntity image in images) {
newItems.add(await image.thumbnailData);
}
return newItems;
}
void _updateData(List<Uint8List?> result) {
if (result.isEmpty) {
state = AsyncValue.data(_items);
} else {
state = AsyncValue.data(_items..addAll(result));
}
_hasMoreItems = _numberOfItemsInFolder > _items.length;
}
Future<void> _fetchFirstBatch() async {
try {
_numberOfItemsInFolder = await (await PhotoManager.getAssetPathList()).firstWhere((element) => element.id == folderId).assetCountAsync;
state = const AsyncValue.loading();
final List<Uint8List?> result = await _fetchNextItems();
_updateData(result);
} catch (e, stk) {
state = AsyncValue.error(e, stk);
}
}
Future<void> fetchNextBatch() async {
if (_alreadyFetching || !_hasMoreItems) return;
_alreadyFetching = true;
log("data updated");
state = AsyncValue.data(_items);
try {
final result = await _fetchNextItems();
_updateData(result);
} catch (e, stk) {
state = AsyncValue.error(e, stk);
log("error catched");
}
_alreadyFetching = false;
}
}
Then I use a scroll controller attached to a CustomScrollView in order to call fetchNextBatch() when the scroll position changes:
#override
void initState() {
if (!controller.hasListeners && !controller.hasClients) {
log("listener added");
controller.addListener(() {
double maxScroll = controller.position.maxScrollExtent;
double position = controller.position.pixels;
if ((position > maxScroll * 0.2 || position == 0) && ref.read(paginationImagesProvider.notifier).mounted) {
ref.read(paginationImagesProvider.notifier).fetchNextBatch();
}
});
}
super.initState();
}
The problem is that when the StateNotifierProvider is fetching more data in the async function fetchNextBatch() and I go back on the navigator (like navigator.pop()), Flutter gives me an error:
[ERROR:flutter/runtime/dart_vm_initializer.cc(41)] Unhandled Exception: Bad state: Tried to use PaginationNotifier after dispose was called.
Consider checking mounted.
I think that the async function responsible of loading data completes after I've popped the page from the Stack (which triggers a Provider dispose).
I'm probably missing something and I still haven't found a fix for this error, any help is appreciated.
I have some stream source (from FlutterReactiveBle library) and reflect it to state managed by StateNotifier.
But I can't sure whether it is right way from the following source. I'm especially afraid of _setState invalidates connectionProvider. And it looks like a bit complicated.
How can I improve this?
It may not work because I wrote it just for illustration.
#freezed
class DeviceConnections with _$DeviceConnections {
const DeviceConnections._();
const factory DeviceConnections({
Map<String, StreamSubscription<void>> connectings,
MapEntry<String, StreamSubscription<void>>? connected,
}) = _DeviceConnections;
}
class SimpleStateNotifier<T> extends StateNotifier<T> {
SimpleStateNotifier(super.state);
void update(T newState) {
state = newState;
}
}
StateNotifierProvider<SimpleStateNotifier<T>, T> simpleStateNotifierProvider<T>(
T initialState,
) {
return StateNotifierProvider<SimpleStateNotifier<T>, T>((ref) {
return SimpleStateNotifier(initialState);
});
}
class DeviceConnector {
DeviceConnector({
required FlutterReactiveBle ble,
required DeviceConnections state,
required Function(DeviceConnections) setState,
required Iterable<String> deviceIds,
}) : _ble = ble,
_state = state,
_setState = setState,
_deviceIds = deviceIds;
final FlutterReactiveBle _ble;
final DeviceConnections _state;
final Function(DeviceConnections) _setState;
final Iterable<String> _deviceIds;
void connect() {
final subscriptions = <String, StreamSubscription<void>>{};
for (final id in _deviceIds) {
subscriptions[id] = _connectInterval(id).listen((event) {});
}
_setState(_state.copyWith(connectings: subscriptions));
}
void disconnect() {
for (final subscription in _state.connectings.values) {
subscription.cancel();
}
_state.connected?.value.cancel();
_setState(DeviceConnections());
}
Stream<void> _connectInterval(String id) async* {
while (true) {
final connection = _ble.connectToDevice(
id: id,
connectionTimeout: Duration(seconds: 10),
);
await for (final update in connection) {
switch (update.connectionState) {
case DeviceConnectionState.connected:
final subscription = _state.connectings[id];
if (subscription != null) {
final others =
_state.connectings.entries.where((x) => x.key != id).toList();
for (final connection in others) {
connection.value.cancel();
}
_setState(
DeviceConnections(connected: MapEntry(id, subscription)),
);
}
break;
default:
break;
}
}
}
}
}
final connectionStateProvider = simpleStateNotifierProvider(
DeviceConnections(),
);
final bleProvider = Provider((_) => FlutterReactiveBle());
class AnotherState extends StateNotifier<List<String>> {
AnotherState(super.state);
}
final anotherStateNotifierProvider = StateNotifierProvider<AnotherState, List<String>>((ref) {
return AnotherState([]);
});
final connectionProvider = Provider((ref) {
final ble = ref.watch(bleProvider);
final connectorState = ref.watch(connectionStateProvider);
final connectorNotifier = ref.watch(connectionStateProvider.notifier);
final deviceIds = ref.watch(anotherStateNotifierProvider);
final connector = DeviceConnector(
ble: ble,
deviceIds: deviceIds,
state: connectorState,
setState: connectorNotifier.update,
);
ref.onDispose(connector.disconnect);
return connector;
});
I protected data_service with current user to only display the current user's habits.
data_service.dart:
class DataService {...
late final Database db;
Users? _user;
late final StreamData<Map<int, Habit>> habits;
Future<void> init() async {
db = await HabitsDb.connectToDb();
habits = StreamData(initialValue: await _getAllHabits(), broadcast: true);
}
String get userEmail => AuthService.firebase().currentUser!.email;
Future<Map<int, Habit>> _getAllHabits() async {
getOrCreateUser(email: userEmail); //issue
final habits = await _getAllHabitsFromDb();
final map = Map<int, Habit>();
final currentUser = _user;
print(currentUser);
for (final habit in habits) {
if (currentUser != null) {
print(currentUser.id);
print(habit.userId);
if (habit.userId == currentUser.id) {
map[habit.id] = habit;
}
}
//map[habit.userId] = currentUser?.id;
}
return map;
}
Future<List<Habit>> _getAllHabitsFromDb() async {
final habitsMap = await HabitsDb.getAllHabits(db);
final habitsList = habitsMap.map((e) => Habit.fromDb(e)).toList();
return habitsList;
}
Future<Users> getOrCreateUser({
required String email,
bool setAsCurrentUser = true,
}) async {
try {
//we found the user
final user = await getUser(email: email);
if (setAsCurrentUser) {
_user = user;
}
print(_user?.email);
return user;
} on CouldNotFindUser {
//we didn't find the user
final createdUser = await createUser(email: email);
if (setAsCurrentUser) {
_user = createdUser;
}
return createdUser;
} catch (e) {
rethrow;
}
}
...}
in main class:
void main() async {
WidgetsFlutterBinding.ensureInitialized();
await Firebase.initializeApp();
final dataService = DataService();
await dataService.init();
GetIt.I.registerSingleton(dataService);
... }
StreamData class:
class StreamData<T> {
List<Habit> _notes = [];
User? _user;
late final StreamController<T> _controller;
Stream<T> get stream => _controller.stream;
late T _value;
T get value => _value;
StreamData({required T initialValue, bool broadcast = true}) {
if (broadcast) {
_controller = StreamController<T>.broadcast();
} else {
_controller = StreamController<T>();
}
_value = initialValue;
}
the problem is that the line getOrCreateUser(email: userEmail); is only called once and it does not work when I switch user and I need to Hot Restart to fix it. I think using Futurebuilder will fix it. but if yes, how do I use it when there is a need to call dataService.init at the beginning of the main?
Since your getOrCreateUser function is declared as async, you'll want to use await when you call it in _getAllHabits:
await getOrCreateUser(email: userEmail)
This ensures the getOrCreateUser code has completed before the rest of the code in _getAllHabits (that depends on the result of getOrCreateUser) executes.
I am try to use a StreamProvider from a StateNotifierProvider.
Here is my StreamProvider, which works fine so far.
final productListStreamProvider = StreamProvider.autoDispose<List<ProductModel>>((ref) {
CollectionReference ref = FirebaseFirestore.instance.collection('products');
return ref.snapshots().map((snapshot) {
final list = snapshot.docs
.map((document) => ProductModel.fromSnapshot(document))
.toList();
return list;
});
});
Now I am trying to populate my shopping cart to have all the products in it from scratch.
final cartRiverpodProvider = StateNotifierProvider((ref) =>
new CartRiverpod(ref.watch(productListStreamProvider));
This is my CartRiverPod StateNotifier
class CartRiverpod extends StateNotifier<List<CartItemModel>> {
CartRiverpod([List<CartItemModel> products]) : super(products ?? []);
void add(ProductModel product) {
state = [...state, new CartItemModel(product:product)];
print ("added");
}
void remove(String id) {
state = state.where((product) => product.id != id).toList();
}
}
The simplest way to accomplish this is to accept a Reader as a parameter to your StateNotifier.
For example:
class CartRiverpod extends StateNotifier<List<CartItemModel>> {
CartRiverpod(this._read, [List<CartItemModel> products]) : super(products ?? []) {
// use _read anywhere in your StateNotifier to access any providers.
// e.g. _read(productListStreamProvider);
}
final Reader _read;
void add(ProductModel product) {
state = [...state, new CartItemModel(product: product)];
print("added");
}
void remove(String id) {
state = state.where((product) => product.id != id).toList();
}
}
final cartRiverpodProvider = StateNotifierProvider<CartRiverpod>((ref) => CartRiverpod(ref.read, []));
i have been trying to get all my data from a sqflite database, when i try to get a single data, this works totally fine:
Future<dynamic> getUser() async {
final db = await database;
var res = await db.query("files");
if (res.length == 0) {
return null;
} else {
var resMap = res[0];
return resMap;
}
}
but when i try to get all data using a for loop like the example below, i get an error
Future<dynamic> getUser() async {
final db = await database;
var res = await db.query("files");
var resMap;
var count = res.length;
if (count != 0) {
for (int i = 0; i < count; i++) {
resMap.add(res[i]);
}
}
return resMap;
}
the error says:
The method 'forEach' was called on null.
Receiver: null
Tried calling: forEach(Closure: (dynamic, dynamic) => Null)
i understand that it says that I've got no data,
and i also tried to remove the if statement, but still no luck!
change this method:
EDIT
Future<List<Map>> getUser() async {
final db = await database;
var res = await db.query("files");
List<Map> resMap = [];
if (res != null res.length > 0) {
for (int i = 0; i < count; i++) {
resMap.add(res[i]);
}
return resMap;
} else
{
return null;
}
}
try this in you widget
List<Map> newUser = [];
#override
void initState() {
super.initState();
getUser();
}
getUser() async {
final _userData = await DBProvider.db.getUser();
if(_userData != null ){
setState(() {
newUser = _userData;
});
} else{
setState(() {
newUser =[];
});
}
}