Looking for an alternative to
#override
Widget build(BuildContext context) {
final _user = useProvider(MyUserProvider);
...
return _user.when(data: data, loading: loading, error: error)
for most of my components
I want to use sth like
final _user = useProvider(MyUserProvider);
// then
return Text(_user.name)
directly because the firebase user data stream is already in the tree and can never be null or have an error.
Can I use a ChangeNotifier to achieve this ?
How else can I achieve this ?
Something like this may work for you:
final authStream = StreamProvider<User?>((ref) => ref.watch(FirebaseAuth.instance).authStateChanges());
final user = Provider<User?>((ref) => ref.watch(authStream).data?.value);
Then:
final _user = useProvider(user);
return Text(_user?.name ?? '');
// or if you're sure the value is not null or your app relies on it being not null
return Text(_user!.name);
You can create a new provider which will depend from the precedent :
final connectedUserProvider = Provider<User>((ref) {
final userState = ref.watch(MyUserProvider.state);
return userState.maybeWhen(data: (User user) => user, orElse: () => throw "you should not be there");
});
Related
(Update at the end of the post) I want to add my normal firebase auth with additional user information. In this example, name and goal calories. For that, I created this register function:
Future<void> signUpWithEmailAndPassword(String email, String password, BuildContext context, WidgetRef ref, widget) async {
FocusManager.instance.primaryFocus?.unfocus();
try {
await auth.createUserWithEmailAndPassword(email: email, password: password);
ref.read(isUp.notifier).state = false;
ref.read(writeItemViewModelProvider).setInitValue();
} on FirebaseAuthException catch (e) {
the function setInitValue() looks like this:
class FirestoreDb extends ChangeNotifier {
Future<void> setInitValue() async {
await firebaseFirestore.collection('/users/${auth.currentUser!.uid}/UserInfo').doc(auth.currentUser!.uid).set({
'name': null,
'calories': null,
});
}
}
Here seems to work everything fine. Inside firestore a file gets created and my user also. Without this additional user infos my auth works also fine. So I think there is a problem with my stream of the user information. Because: I have to check if the registert user has already added information or not.
I do this with a second .when function:
#override
Widget build(BuildContext context, WidgetRef ref) {
final authState = ref.watch(authStateProvider);
final watcher = ref.watch(itemsProvider);
return authState.when(
data: (data) {
if (data != null) {
return watcher.when(data: (calo) {
if (calo.first.calories != null) {
return const RootPage();
} else {
return UserInformation();
}
}, error: (e, trace) => ErrorScreen(e, trace), loading: () => const LoadingScreen());
the first .when function is for the auth, here seems to be no problem, but the secons is strange. When I login first time, it says bad state. From now on, every time I register with a different account, I only get the old data from the previous account until I hot restart.
After the user information, you get to this page:
#override
Widget build(BuildContext context, WidgetRef ref) {
final streamData = ref.watch(itemsProvider);
return Scaffold(
backgroundColor: Theme.of(context).backgroundColor,
appBar: AppBar(toolbarHeight: 0, backgroundColor: Colors.transparent),
resizeToAvoidBottomInset: false,
body: streamData.when( data: (calo) {
return Text(calo.first.calories.toString());
}, error: (e, trace) => ErrorScreen(e, trace), loading: () => const LoadingScreen())
);
}
where I can see that s old information until hot restart.
So something with my stream is not updating the state correctly.
When I wrap delete the .when function and use a Streambuilder listening to the stream directly everything works.
Here is my itemsProvider:
final itemsProvider = StreamProvider<List<UsersModel>>(
(ref) => ref.read(itemRepositoryProvider).itemsStream,
);
final itemRepositoryProvider = Provider((ref) => ReadData());
class ReadData{
Stream<List<UsersModel>> get itemsStream {
return firebaseFirestore.collection('/users/${auth.currentUser!.uid}/UserInfo').snapshots().map((QuerySnapshot query) {
List<UsersModel> user = [];
for (var usersIter in query.docs) {
final usersModel = UsersModel.fromDocumentSnapshot(documentSnapshot: usersIter);
user.add(usersModel);
}
return user;
});
}
}
I check with debugging and "print points" the way of the compiler and recognised the problem but have no answer why the compiler do this:
#override
Widget build(BuildContext context, WidgetRef ref) {
print("inside UserInfoBuild");
final watcher = ref.watch(itemsProvider);
return watcher.when(data: (userInfoData) {
print("inside AsyncValue<List<UsersModel>>");
if (userInfoData.first.calories != null) {
return const RootPage();
} else {
return UserInformation(); [...]
declare provider:
final itemsProvider = StreamProvider<List<UsersModel>>(
(ref) {
print("inside stream provider");
return ref.read(itemRepositoryProvider).itemsStream;
},
);
so, my guess was that the print order should be:
I/flutter: inside UserInfoBuild
I/flutter: inside stream provider
I/flutter: inside AsyncValue<List<UsersModel>>
but its actually just:
I/flutter: inside UserInfoBuild
I/flutter: inside AsyncValue<List<UsersModel>>
so the compiler skips the final itemsProvider = StreamProvider.
Just after a hot restart it executes the line of code
I think the key point is 'get' itemsStream. You have two ways to try.
// 1.
final itemsProvider = StreamProvider<List<UsersModel>>(
(ref) => firebaseFirestore.collection('/users/${auth.currentUser!.uid}/UserInfo').snapshots().map((QuerySnapshot query) {
List<UsersModel> user = [];
for (var usersIter in query.docs) {
final usersModel = UsersModel.fromDocumentSnapshot(documentSnapshot: usersIter);
user.add(usersModel);
}
return user;
}),
);
// 2.
You can use StreamController to get data from firebaseFirestore.collection in ReadData class, and use a Stream variable to sync that value. Update StreamProvider to the Stream variable.
I'm completely stuck with the task below.
So, the idea is to solve these steps using Riverpod
Fetch data from db with some kind of Future async while pausing the app (display SomeLoadingPage() etc.)
Once the data has loaded:
2.1 initialize multiple global StateNotifierProviders which utilize the data in their constructors and can further be used throughout the app with methods to update their states.
2.2 then show MainScreen() and the rest of UI
So far I've tried something like this:
class UserData extends StateNotifier<AsyncValue<Map>> { // just <Map> for now, for simplicity
UserData() : super(const AsyncValue.loading()) {
init();
}
Future<void> init() async {
state = const AsyncValue.loading();
try {
final HttpsCallableResult response =
await FirebaseFunctions.instance.httpsCallable('getUserData').call();
state = AsyncValue.data(response.data as Map<String, dynamic>);
} catch (e) {
state = AsyncValue.error(e);
}}}
final userDataProvider = StateNotifierProvider<UserData, AsyncValue<Map>>((ref) => UserData());
final loadingAppDataProvider = FutureProvider<bool>((ref) async {
final userData = await ref.watch(userDataProvider.future);
return userData.isNotEmpty;
});
class LoadingPage extends ConsumerWidget {
#override
Widget build(BuildContext context, WidgetRef ref) {
return FutureBuilder(
future: ref.watch(loadingAppDataProvider.future),
builder: (ctx, AsyncSnapshot snap) {
// everything here is simplified for the sake of a question
final Widget toReturn;
if (snap.connectionState == ConnectionState.waiting) {
toReturn = const SomeLoadingPage();
} else {
snap.error != null
? toReturn = Text(snap.error.toString())
: toReturn = const SafeArea(child: MainPage());
}
return toReturn;},);}}
I intentionally use FutureBuilder and not .when() because in future i may intend to use Future.wait([]) with multiple futures
This works so far, but the troubles come when I want to implement some kind of update() methods inside UserData and listen to its variables through the entire app. Something like
late Map userData = state.value ?? {};
late Map<String, dynamic> settings = userData['settings'] as Map<String, dynamic>;
void changeLang(String lang) {
print('change');
for (final key in settings.keys) {
if (key == 'lang') settings[key] = lang;
state = state.whenData((data) => {...data});
}
}
SomeLoadingPage() appears on each changeLang() method call.
In short:
I really want to have several StateNotifierProviders with the ability to modify their state from the inside and listen to it from outside. But fetch the initial state from database and make the intire app wait for this data to be fetched and these providers to be initilized.
So, I guess I figured how to solve this:
final futureExampleProvider = FutureProvider<Map>((ref) async {
final HttpsCallableResult response =
await FirebaseFunctions.instance.httpsCallable('getUserData').call();
return response.data as Map;
});
final exampleProvider = StateNotifierProvider<Example, Map>((ref) {
// we get AsyncValue from FutureNotifier
final data = ref.read(futureExampleProvider);
// and wait for it to load
return data.when(
// in fact we never get loading state because of FutureBuilder in UI
loading: () => Example({'loading': 'yes'}),
error: (e, st) => Example({'error': 'yes'}),
data: (data) => Example(data),
);
});
class LoadingPage extends ConsumerWidget {
#override
Widget build(BuildContext context, WidgetRef ref) {
return FutureBuilder(
// future: ref.watch(userDataProvider.future),
future: ref.watch(futureExampleProvider.future),
builder: (ctx, AsyncSnapshot snap) {
final Widget toReturn;
if (snap.data != null) {
snap.error != null
? toReturn = Text(snap.error.toString())
: toReturn = const SafeArea(child: MainPage());
} else {
// this is the only 'Loading' UI the user see before everything get loaded
toReturn = const Text('loading');
}
return toReturn;
},
);
}
}
class Example extends StateNotifier<Map> {
Example(this.initData) : super({}) {
// here comes initial data loaded from FutureProvider
state = initData;
}
// it can be used further to refer to the initial data, kinda like cache
Map initData;
// this way we can extract any parts of initData
late Map aaa = state['bbb'] as Map
// this method can be called from UI
void ccc() {
// modify and update data
aaa = {'someKey':'someValue'};
// trigger update
state = {...state};
}
}
This works for me, at least on this level of complexity.
I'll leave question unsolved in case there are some better suggestions.
This is what I'm trying to achieve using flutter GetX package but not working properly.
I have a Firestore document, if the document is changed I want to call an api and keep the data up to date as observable.
The code below seems to work but initial screen shows null error then it shows the data.
I don't know how I can make sure both fetchFirestoreUser() and fetchApiData() (async methods) returns data before I move to the home screen.
GetX StateMixin seems to help with async data load problem but then I don't know how I can refresh the api data when the firestore document is changed.
I'm not sure if any other state management would be best for my scenario but I find GetX easy compared to other state management package.
I would very much appreciate if someone would tell me how I can solve this problem, many thanks in advance.
Auth Controller.
class AuthController extends SuperController {
static AuthController instance = Get.find();
late Rx<User?> _user;
FirebaseAuth auth = FirebaseAuth.instance;
var _firestoreUser = FirestoreUser().obs;
var _apiData = ProfileUser().obs;
#override
void onReady() async {
super.onReady();
_user = Rx<User?>(auth.currentUser);
_user.bindStream(auth.userChanges());
//get firestore document
fetchFirestoreUser();
//fetch data from api
fetchApiData();
ever(_user, _initialScreen);
//Refresh api data if firestore document has changed.
_firestoreUser.listen((val) {
fetchApiData();
});
}
Rx<FirestoreUser?> get firestoreUser => _firestoreUser;
_initialScreen(User? user) {
if (user == null) {
Get.offAll(() => Login());
} else {
Get.offAll(() => Home());
}
}
ProfileUser get apiData => _apiData.value;
void fetchFirestoreUser() async {
Stream<FirestoreUser> firestoreUser =
FirestoreDB().getFirestoreUser(_user.value!.uid);
_firestoreUser.bindStream(firestoreUser);
}
fetchApiData() async {
var result = await RemoteService.getProfile(_user.value!.uid);
if (result != null) {
_apiData.value = result;
}
}
#override
void onDetached() {}
#override
void onInactive() {}
#override
void onPaused() {}
#override
void onResumed() {
fetchApiData();
}
}
Home screen
class Home extends StatelessWidget {
const Home({Key? key}) : super(key: key);
#override
Widget build(BuildContext context) {
return Scaffold(
body: Center(
child: Container(
child: Obx(() =>
Text("username: " + AuthController.instance.apiData.username!))),
),
);
}
}
To be honest, I never used GetX so I'm not too familiar with that syntax.
But I can see from your code that you're setting some mutable state when you call this method:
fetchApiData() async {
var result = await RemoteService.getProfile(_user.value!.uid);
if (result != null) {
_apiData.value = result;
}
}
Instead, a more robust solution would be to make everything reactive and immutable. You could do this by combining providers if you use Riverpod:
final authStateChangesProvider = StreamProvider.autoDispose<User?>((ref) {
final authService = ref.watch(authRepositoryProvider);
return authService.authStateChanges();
});
final apiDataProvider = FutureProvider.autoDispose<APIData?>((ref) {
final userValue = ref.watch(authStateChangesProvider);
final user = userValue.value;
if (user != null) {
// note: this should also be turned into a provider, rather than using a static method
return RemoteService.getProfile(user.uid);
} else {
// decide if it makes sense to return null or throw and exception when the user is not signed in
return Future.value(null);
}
});
Then, you can just use a ConsumerWidget to watch the data:
#override
Widget build(BuildContext context, WidgetRef ref) {
// this will cause the widget to rebuild whenever the auth state changes
final apiData = ref.watch(apiDataProvider);
return apiData.when(
data: (data) => /* some widget */,
loading: () => /* some loading widget */,
error: (e, st) => /* some error widget */,
);
}
Note: Riverpod has a bit of a learning curve (worth it imho) so you'll have to learn it how to use it first, before you can understand how this code works.
Actually the reason behind this that you put your controller in the same page that you are calling so in the starting stage of your page Get.put() calls your controller and because you are fetching data from the API it takes a few seconds/milliseconds to get the data and for that time your Obx() renders the error. To prevent this you can apply some conditional logic to your code like below :
Obx(() => AuthController.instance.apiData != null ? Text("username: " + AuthController.instance.apiData.username!) : CircularProgressIndicator())) :
I am using a future provider to display a login page on load and then a loading indicator on loading. Here is my future provider
final loginProvider = FutureProvider.family((ref, UserInput input) =>
ref.read(authRepositoryProvider).doLogin(input.email, input.password));
In my UI I have this....
class LoginScreen extends HookWidget {
final TextEditingController emailEditingController = TextEditingController();
final TextEditingController passwordEditingController =
TextEditingController();
#override
Widget build(BuildContext context) {
var userInput =
UserInput(emailEditingController.text, passwordEditingController.text);
final login = useProvider(loginProvider(userInput));
return login.when(
data: (user) => Login(emailEditingController, passwordEditingController),
loading: () => const ProgressIndication(),
error: (error, stack) {
if (error is DioError) {
return Login(emailEditingController, passwordEditingController);
} else {
return Login(emailEditingController, passwordEditingController);
}
},
);
}
}
here is my doLogin function.
#override
Future<dynamic> doLogin(String email, String password) async {
try {
final response = await _read(dioProvider)
.post('$baseUrl/login', data: {'email': email, 'password': password});
final data = Map<String, dynamic>.from(response.data);
return data;
} on DioError catch (e) {
return BadRequestException(e.error);
} on SocketException {
return 'No Internet Connection';
}
}
I would like to know why it's stuck in the loading state. Any help will be appreciated.
First off, family creates a new instance of the provider when given input. So in your implementation, any time your text fields change, you're generating a new provider and watching that new provider. This is bad.
In your case, keeping the UserInput around for the sake of accessing the login state doesn't make a lot of sense. That is to say, in this instance, a FamilyProvider isn't ideal.
The following is an example of how you could choose to write it. This is not the only way you could write it. It is probably easier to grasp than streaming without an API like Firebase that handles most of that for you.
First, a StateNotifierProvider:
enum LoginState { loggedOut, loading, loggedIn, error }
class LoginStateNotifier extends StateNotifier<LoginState> {
LoginStateNotifier(this._read) : super(LoginState.loggedOut);
final Reader _read;
late final Map<String, dynamic> _user;
static final provider =
StateNotifierProvider<LoginStateNotifier, LoginState>((ref) => LoginStateNotifier(ref.read));
Future<void> login(String email, String password) async {
state = LoginState.loading;
try {
_user = await _read(authRepositoryProvider).doLogin(email, password);
state = LoginState.loggedIn;
} catch (e) {
state = LoginState.error;
}
}
Map<String, dynamic> get user => _user;
}
This allows us to have manual control over the state of the login process. It's not the most elegant, but practically, it works.
Next, a login screen. This is as barebones as they get. Ignore the error parameter for now - it will be cleared up in a moment.
class LoginScreen extends HookWidget {
const LoginScreen({Key? key, this.error = false}) : super(key: key);
final bool error;
#override
Widget build(BuildContext context) {
final emailController = useTextEditingController();
final passwordController = useTextEditingController();
return Column(
children: [
TextField(
controller: emailController,
),
TextField(
controller: passwordController,
),
ElevatedButton(
onPressed: () async {
await context.read(LoginStateNotifier.provider.notifier).login(
emailController.text,
passwordController.text,
);
},
child: Text('Login'),
),
if (error) Text('Error signing in'),
],
);
}
}
You'll notice we can use the useTextEditingController hook which will handle disposing of those, as well. You can also see the call to login through the StateNotifier.
Last but not least, we need to do something with our fancy new state.
class AuthPage extends HookWidget {
const AuthPage({Key? key}) : super(key: key);
#override
Widget build(BuildContext context) {
final loginState = useProvider(LoginStateNotifier.provider);
switch (loginState) {
case LoginState.loggedOut:
return LoginScreen();
case LoginState.loading:
return LoadingPage();
case LoginState.loggedIn:
return HomePage();
case LoginState.error:
return LoginScreen(error: true);
}
}
}
In practice, you're going to want to wrap this in another widget with a Scaffold.
I know this isn't exactly what you asked, but thought it might be helpful to see another approach to the problem.
I am trying to write and read data using shared preferences, but I didn't know how to read for more than one data.. The route is like this... I have 3 screens (Login, Home, and Profile screen) inside Home and Profile Screen consist of bottom tab navigator... so after I pass Login Screen, I want to save username and id to pass it inside Home and Profile Screen... so far I have saved username and id inside Login Screen and I just didn't get the idea how to read both of them.. here is the code
class _BottomTab extends State<BottomTab> {
#override
Widget build(BuildContext context) {
return FutureProvider<String>(
create: (context) async {
final prefs = await SharedPreferences.getInstance();
return prefs.getString("username");
},
child: ...,
);
}
}
}
here is when calling username but I didn't know how the way to call id
Widget build() {
final username = Provider.of<String>(context).toString();
if (username == null) {
return "Loading...";
}
return Text("Hi $username");
}
I have tried to make a new function and define that function inside initState()... but the problem is the data always re-build whenever I click bottomTab... that's why I didn't use this method (declare function inside initState)
do like this
class _BottomTab extends State<BottomTab> {
#override
Widget build(BuildContext context) {
return FutureProvider<String/* or 'Map' if you can*/>(
create: (context) async {
final prefs = await SharedPreferences.getInstance();
final username = prefs.getString("username");
final id = prefs.getId("id");
final userMap = {"username":username, "id":id};
// return userMap /* if return type is Map */
return json.encode(userMap); /* if return type is String */
},
child: ...,
);
}
}
}
now call
Widget build() {
final userInfo = Provider.of<String>(context).toString();
final userMap = json.encode(userStr);
final username = userMap["username"];
if (username == null) {
return "Loading...";
}
return Text("Hi $username");
}
!!! this code have not been tested