I'm making a website and I would like to show a loading_page until the home_page is loaded and then transition from one to the other as soon as possible (no fixed timers).
There are multiple ways to do this (ie., using the simplest setState, Streams, multiple packages for state management, just to name a few). I'll give you a simple example just by using a StatefulWidget where you call your API on initState and then navigate when you're done to your new screen.
class LoadingPage extends StatefulWidget {
const LoadingPage({Key? key}) : super(key: key);
#override
_LoadingPageState createState() => _LoadingPageState();
}
class _LoadingPageState extends State<LoadingPage> {
#override
void initState() {
super.initState();
_fetchFromAPI();
}
Future<void> _fetchFromAPI() async {
// Call some API, do anything you want while loading
Navigator.pushReplacementNamed(context, '/home_page');
}
#override
Widget build(BuildContext context) {
return Scaffold(
body: const CircularProgressIndicator(),
);
}
}
You can use future builder for this purpose.
Have a look at: https://api.flutter.dev/flutter/widgets/FutureBuilder-class.html
You can fetch the data as snapshot and use the snapshot.hasdata to check if data is being received or not and till then you can show CircularProgreswIndicator() to show the loading..
Related
I come from the web dev world. I have designed a Flutter app that needs to grab some JSON from the web very early on. I want my first screen to show up, and while it is being drawn, behind the scenes I want the JSON fetch to happen. There is a start button on Page 1 that will be disabled until the JSON is fetched. (But Page 1 will have some text info to keep the reader engaged until the fetch happens.)
Where would I stick the JSON fetch? Can I put it in initState of Page 1? Or can I initiate a call at the very start of main at the root of the app? Or somewhere else?
FWIW I use Provider for state management, if that helps?
Thanks a ton!
Calling it in the initState is best since your widgets still build. Since there will be a state change, make sure you use a stateful widget. Also, don't forget to call setState to re-enable the button. Example code:
class FirstPage extends StatefulWidget {
const FirstPage({Key? key}) : super(key: key);
#override
State<FirstPage> createState() => _FirstPageState();
}
class _FirstPageState extends State<FirstPage> {
#override
void initState() {
super.initState();
jsonFetch();
}
void jsonFetch() {
// your functionality here
// on complete call:
/*
setState(() {
isJsonFetched = true;
});
*/
}
void doSomethingOnPressed(){
// Your functionality here
}
bool isJsonFetched = false;
#override
Widget build(BuildContext context) {
return Scaffold(
body: Container(
child: ElevatedButton(
onPressed: (){
isJsonFetched
? doSomethingOnPressed()
:null;
},
child: Text('Press Me')
)
)
);
}
}
I had firebase dynamic links integrated and working fine in my app and later i changed to use go_router and now i don't know what i should do to get it working or how to handle it.
The way i imagined it would be is that the FB dynamic link path will be the same as the path to the page in GoRouter routes, and go_router will redirect to the page automatically but i don't think that is how it works and i can't find any resources for this.
So the question is how to use Firebase DynamicLinks with go_router?
this is how I did it, looks like working fine :)
For when the app is in terminated mode:
Future main() async {
...
// Closed state: getInitialLink is Used
final PendingDynamicLinkData? initialLink =
await FirebaseDynamicLinks.instance.getInitialLink();
...
then through runApp(MtApp(initialRoute: initialLink)) pass it to GoRouter.initialLocation field or GoRouter.redirect function, depending on how you use it.
For when the app is in background:
wrap your top widget with a statefulWidget your created like:
class AHDynamicLinksManager extends
StatefulWidget {
final Widget child;
const AHDynamicLinksManager({required this.child, Key? key})
: super(key: key);
#override
State<AHDynamicLinksManager> createState() => _AHDynamicLinksManagerState();
}
class _AHDynamicLinksManagerState extends State<AHDynamicLinksManager> {
#override
void initState() {
super.initState();
FirebaseDynamicLinks.instance.onLink.listen((dynamicLinkData) {
String goingTo = dynamicLinkData.link.path;
GoRouter.of(context).go(goingTo);
}).onError((error) {
GoRouter.of(context).go("/errorpage/$error");
});
}
#override
Widget build(BuildContext context) {
return widget.child;
}
}
Hope it helped!
I am trying to wait till amplify configuration is done then load the login screen. Even though state seems to be getting updated I am still getting the loadinscreen. Why is that?
I am not sure if setState is proper method on the init : Importance of Calling SetState inside initState
As per the doc : https://docs.amplify.aws/start/getting-started/integrate/q/integration/flutter/#configure-amplify
Future<void> main() async {
runApp(MyApp());
}
class MyApp extends StatefulWidget {
MyApp({Key? key}) : super(key: key);
#override
State<MyApp> createState() => _MyAppState();
}
class _MyAppState extends State<MyApp> {
bool _isAmplifyConfigured = false;
late AmplifyAuthCognito auth;
#override
void initState() {
_initializeApp();
super.initState();
}
Future<void> _initializeApp() async {
await _configureAmplify();
setState(() {
_isAmplifyConfigured = true;
});
}
Future<void> _configureAmplify() async {
auth = AmplifyAuthCognito();
try {
await Amplify.addPlugin(auth);
await Amplify.configure(amplifyconfig);
} on AmplifyAlreadyConfiguredException {
print(
'Amplify was already configured. Looks like app restarted on android.');
}
}
#override
Widget build(BuildContext context) {
return MaterialApp(
onGenerateRoute: AppRoutes.onGenerateRoute,
initialRoute: _isAmplifyConfigured
? LoginScreen.routeName
: LoadingScreen.routeName,
);
}
}
I think the issue is with you trying to reassign your initialRoute. I'm not super familiar with this property, but given the name I assume this is set once and is not rebuilt, not even when the state changes. It would make sense, also, because the rest of your code sounds like it should work.
Before trying anything else, I'd recommend you move your logic to initialize Amplify to the LoginScreen, and having its body depend on the _isAmplifyConfigured boolean value. So show spinner if it's false, and show Login fields when it's true.
Even better would be to create a HomeScreen, so you can keep this Amplify initialization at the bottom of your app's stack. And then have your HomeScreen either show the Login widgets, the home screen of your app, or a loading state.
i am facing an issue with Pageview and Futurebuild, that every-time i switch between first page and second page the page will be rebuilt again...it will call new data from API even if there is nothing new...anyone can help me in this
class Home extends StatefulWidget {
const Home({Key key}) : super(key: key);
#override
_HomeState createState() => _HomeState();
}
class _HomeState extends State<Home> {
PageController pageController = PageController(keepPage: false);
#override
void initState() {
super.initState();
}
}
#override
void dispose() {
super.dispose();
}
#override
Widget build(BuildContext context) {
final homePage = HomeProjects(pageController: pageController);
final portfolioPage = Portfolio(pageController: pageController);
return Scaffold(
body: ScrollConfiguration(
behavior: MyBehavior(),
child: PageView(reverse: true, controller: pageController,
//physics: NeverScrollableScrollPhysics(),
children: [
homePage,
portfolioPage,
]),
),
);
}
}
If you are only making HTTP calls inside your pages that's a desired outcome. You'll need to cache the responses to avoid repeated network calls.
Moving api calls to initState is not something I would personally do - the data fetched on first page creation may become outdated without you knowing it.
Well, you build your pages every time build is called.
If you don't want that, move the lines that actually build the pages to a time and place where they will be called only once. initState might be a good place.
I have a bottom navigation bar from my MaterialApp and one of the pages use FutureBuilder to retrieve data from my RESTful API. My bottom navigation bar needs to save the state of the pages, So I came across this guide on how to keep the state of my bottom navigation bar using PageStorage.
The issue I have encountered is that whenever I navigate out of the FutureBuilder page and back again, it rebuilds the entire page and re-executes my Future method.
I also read another guide on using AsyncMemoizer to run my Future method only once (It still rebuilds the page, but much faster). The snippet of code below is how I have implemented it.
//Unsure why AsyncMemoizer somehow only works if I use StatelessWidget, and not StatefulWidget
class FuturePage extends StatelessWidget {
/*I had to comment this constructor out because AsyncMemoizer must be
initialised with a constant value */
//const FuturePage({Key key}) : super(key: key);
//To store my PageStorageKey into bucket
FuturePage({Key key}) : super(key: key);
final _memoizer = new AsyncMemoizer();
_fetchData() => this._memoizer.runOnce(_myFutureMethod);
Future<MyType> _myFutureMethod() async => print("Executed"); //await post and return data
#override
Widget build(BuildContext context) {
return Container(
child: FutureBuilder(
future: _fetchData(),
builder: (context, snapshot) {
if (snapshot.hasData) {
//set up my widgets
}
return Center(child: CircularProgressIndicator());
}
);
}
}
On the output log, Executed is only displayed once. However, I need to use a StatefulWidget instead of StatelessWidget, and AsyncMemoizer wouldn't work in my case.
class FuturePage extends StatefulWidget {
FuturePageState createState() => FuturePageState();
const FuturePage({Key key}) : super(key: key);
}
How do I save the state of my FutureBuilder Page using StatefulWidget? I'm still relatively new to flutter and the concepts of reactive programming. Sincerest apologies if I happen to be doing something wrongly!
To achieve this behavior you can use the AutomaticKeepAliveClientMixin
class FuturePage extends StatefulWidget {
const FuturePage({Key key}) : super(key: key);
#override
FuturePageState createState() => FuturePageState();
}
You need to implement AutomaticKeepAliveClientMixin
class FuturePageState extends State<FuturePage> with AutomaticKeepAliveClientMixin<FuturePage>{
#override
bool get wantKeepAlive => true;
#override
Widget build(BuildContext context) {
super.build(context); // call super method
return // Your Widget
}
}