In Flutter,
I used FutureBuilder to display data from API.
I would like to popup an error dialog when there's error.
However, it throws error when I called showDialog()
setState() or markNeedsBuild() called during build.
Here's my code
return FutureBuilder(
future: xxx,
builder: (context, snapshot) {
if (snapshot.hasData) {
//DO SOMETHING
} else if (snapshot.hasError) {
//TODO: Show Error
showDialog(
context: context,
builder: (BuildContext context) {
return AlertDialog(
title: Text("Error"),
content: Text("HAHAHA"),
actions: <Widget>[
FlatButton(
child: Text("No"),
),
FlatButton(
child: Text("Yes")
),
],
);
}
);
return Container();
} else {
//DO SOMETHING
}
},
Please help to advise how could I showDialog in FutureBuilder.
We can not call setState, navigate or showDialog while build method is building widget. so, we can wait for a microsecond and meanwhile build method complete building widget, so we can show dialog.
Create a method like below.
showError() async {
await Future.delayed(Duration(microseconds: 1));
showDialog(
context: context,
builder: (BuildContext context) {
return AlertDialog(
title: Text("Error"),
content: Text("HAHAHA"),
actions: <Widget>[
FlatButton(
child: Text("No"),
),
FlatButton(child: Text("Yes")),
],
);
});
}
And call this method Where you want to show dialog.
Related
How to set global variable using OK button on AlertDialog in StatefulBuilder?
String stringMain = "My String";
Future<String?> dialogChangeMainContent(BuildContext context) {
return showDialog<String>(
context: context,
builder: (BuildContext context) {
return StatefulBuilder(builder: (context, setState) {
return AlertDialog(
title: const Text('AlertDialog Title'),
content: const Text('AlertDialog description'),
actions: <Widget>[
TextButton(
onPressed: () {
Navigator.pop(context, 'OK');
setState(() {
// setState2();
stringMain = "New String";
});
},
child: const Text('OK'),
),
],
);
});
});
}
I changed StatefulWidget from StatelessWidget, but nothing changes. What I know is the problem is because the button is in the StatefulBuilder. If using BLoC etc, it's too wasteful for only small applications.
I found a way to solve my problem, redrawing (refreshing) the Text (or other widget) in a Stateless Widget from an AlertDialog in a StatefulBuilder. By creating a setState with a different name, for example setStateTarget.
Without having to rebuild the entire page, or without state management like BLoC. My code:
String stringMain = "My String";
#override
Widget build(BuildContext context) {
return Column(
// ....
children: [
StatefulBuilder(builder: (BuildContext context, setStateTarget) {
return Column(children: [
Text(stringMain), // <--- target
TextButton(
onPressed: () => dialogChangeMainContent(context, setStateTarget),
child: const Text('Show Dialog'))
]);
})
],
);
}
Future<String?> dialogChangeMainContent(BuildContext context, StateSetter setStateTarget) {
return showDialog<String>(
context: context,
builder: (BuildContext context) {
return StatefulBuilder(builder: (context, setState) {
return AlertDialog(
title: const Text('AlertDialog Title'),
content: const Text('AlertDialog description'),
actions: <Widget>[
TextButton(
onPressed: () {
Navigator.pop(context, 'OK');
setStateTarget(() {
// setState2();
stringMain = "New String";
});
},
child: const Text('OK'),
),
],
);
});
});
}
I´m new in the bloc pattern. I want to show up an alert dialog when I press a button, but when I use showDialog func and showDialog I want to access Bloc from context or BlocListner doesn't contain bloc and throw error is there a way to access bloc in this situatuion
Error: Could not find the correct Provider above this BlocListener<TeacherFinancialCubit, TeacherFinancialState> Widget
#override
Widget build(BuildContext context) {
return BlocBuilder<UserBloc, UserState>(
builder: (context, state) {
if(state is! Authorize) {
return const BaBaFullScreenLoading();
}
return BlocProvider<TeacherFinancialCubit>(
lazy: false,
create: (context) => TeacherFinancialCubit(locator())..getTeacherFinancial(state.user, state.account, teacherId ?? 0),
child: _masterLayout(context),
);
},
);
}
Widget _masterLayout(BuildContext context) {
Authorize authorize = context.read<UserBloc>().state as Authorize;
return MasterLayout(
showBack: true,
floatingActionButton: authorize.account.type == master ? FloatingActionButton(
child: const Icon(Icons.add),
onPressed: () {
Future.microtask(() => _showAddPaymentDialog(context));
},
) : null,
title: const Text(""),
child: WillPopScope(
onWillPop: () => Future.value(false),
child: _showTeacherFinancials(context, authorize),
),
);
}
void _showAddPaymentDialog(BuildContext context) async {
return showDialog(
barrierDismissible: false,
context: context,
builder: (_) {
return BlocListener<TeacherFinancialCubit, TeacherFinancialState>(
listener: (context, state) {
if(state is TeacherFinancialLoading) {
EasyLoadingHelper.showLoading();
}
else {
EasyLoadingHelper.dismiss();
if(state is TeacherFinancialFailed) {
EasyLoadingHelper.showToastError(context, message: state.error);
}
else if(state is TeacherFinancialSuccess) {
EasyLoadingHelper.showToastSuccess(context, message: successMessage);
Navigator.pop(context);
}
}
},
child: AlertDialog(
title: const Text(''),
content: Form(
key: addPaymentFormKey,
child: Text(""),
),
actions: [],
),
);
}
);
}
Make sure to provide the bloc to the AlertDialog. You can do something like this:
return showDialog(
...
builder: (dialogContext) => BlocProvider.value(
value: BlocProvider.of<TeacherFinancialCubit>(context),
child: BlocListener<TeacherFinancialCubit, TeacherFinancialState>(
...
),
),
Basically I have a button(GestureDetector) which to call Future function in the same file. The thing is the widget in that function does not appear as it should but the background process is successfully running.
The trigger:
showDialog(
context: context,
builder: (context) {
AlertDialog(
/// Below the button to call function *resetPassword*
GestureDetector(
child: Text("Yes"),
onTap: () async {
Navigator.of(context).pop();
resetPassword('manan#gmail.com')}))})
The widget function:
Future<Widget> resetPassword(email) async {
try{
await FirebaseAuth.instance.sendPasswordResetEmail(email: email)
return AlertDialog(
///the content of dialog)
}on FirebaseAuthException catch (e) {
return AlertDialog(
///the content of dialog)
}}
Surprisingly the email of reset password was successfully sent.
Disclaimer: I am new to Flutter, hopefully sifus can considerate it.
When you're working with dialogs in general you have to wrap it with showDialog() method, like:
await showDialog(
context: context,
builder: (BuildContext context) {
return AlertDialog(
title: Center(child: Text('Reset password')),
content: Builder(
builder: (context) {
return Container(child: ForgotPasswordForm());
},
),
);
},
);
Secondly, I see that you have nested Alert Dialog widgets and I think you should restructure this.
I am try pass context to second widget tree (in function) but I get error:
Tried to use Provider with a subtype of Listenable/Stream (Model2).
This is likely a mistake, as Provider will not automatically update
dependents when Model2 is updated. Instead, consider changing Provider
for more specific implementation that handles the update mecanism,
such as:
- ListenableProvider
- ChangeNotifierProvider
- ValueListenableProvider
- StreamProvider
Future<void> _neverSatisfied({Key key, #required BuildContext context}) async {
final model2 = Provider.of<Model2>(context, listen: false);
return showDialog<void>(
context: context,
barrierDismissible: false,
builder: (BuildContext context) {
return
Provider.value(value: model2, child:
AlertDialog(
title: Text('Rewind and remember'),
content: SingleChildScrollView(
child: ListBody(
children: <Widget>[
Text('You will never be satisfied.'),
Text('You\’re like me. I’m never satisfied.'),
],
),
),
actions: <Widget>[
FlatButton(
child: Text('Regret'),
onPressed: () async {
await model2.getData();
Navigator.of(context).pop();
},
),
],
),
);
},
);
}
First widget in same StatefulWidget:
#override
Widget build(BuildContext context) {
return ChangeNotifierProxyProvider<Model1, Model2>(
initialBuilder: (_) => Model2(),
builder: (_, model1, model2) => model2
..string = model1.string,
),
child: Consumer<Model2>(
builder: (context, model2, _) =>
Second (I pass context from here):
#override
Widget buildStep(BuildContext context) {
Consumer<Model2>(
builder: (context, model2, _) =>
...
_neverSatisfied(context: context); //**pass context**
Instead of Provider.value you should use ChangeNotifierProvider.value
I want to show a dialog if I receive an error in a futurebuilder.
If I receiver an error, I want to show a dialog and force the user to click on the button, so that he can be redirected to another page.
The problems seems to be that it is not possible to show a dialog while widget is being built.
FutureBuilder(
future: ApiService.getPosts(),
builder: (BuildContext context, AsyncSnapshot snapShot) {
if (snapShot.connectionState == ConnectionState.done) {
if (snapShot.data.runtimeType == http.Response) {
var message =
json.decode(utf8.decode(snapShot.data.bodyBytes));
showDialog(
context: context,
barrierDismissible: false,
builder: (context) {
return AlertDialog(
content: Text(message),
actions: <Widget>[
FlatButton(
child: Text("Ok"),
onPressed: () => null",
)
],
);
});
}
return ListView.separated(
separatorBuilder: (BuildContext context, int index) {
return Divider(
color: Colors.grey,
height: 1,
);
},
itemBuilder: (BuildContext context, int index) {
return _buildPostCard(index);
},
itemCount: snapShot.data.length,
);
return Center(
child: CircularProgressIndicator(),
);
},
)
If I return the AlertDialog alone, it works. But I need the showDialog because of the barrierDismissible property.
Does any one know if that is possible?
Also, is this a good way to handle what I want?
Thanks
UPDATE
For further reference, a friend at work had the solution.
In order to do what I was looking for, I had to decide which future I was going to pass to the futureBuilder.
Future<List<dynamic>> getPostsFuture() async {
try {
return await ApiService.getPosts();
} catch (e) {
await showDialog(
context: context,
barrierDismissible: false,
builder: (context) {
return AlertDialog(
content: Text(message),
actions: <Widget>[
FlatButton(
child: Text("Ok"),
onPressed: () => null",
)
],
);
});
}
}
}
Then in the futureBuilder I would just call
FutureBuilder(
future: getPostsFuture(),
Thanks
To avoid setState() or markNeedsBuild() called during build error when using showDialog wrap it into Future.delayed like this:
Future.delayed(Duration.zero, () => showDialog(...));
setState() or markNeedsBuild() called during build.
This exception is allowed because the framework builds parent widgets before its children, which means a dirty descendant will always be built. Otherwise, the framework might not visit this widget during this build phase.
So to avoid that Future Callback is used, which adds a call like this EventQueue.
class HomeScreen extends StatefulWidget {
#override
_HomeScreenState createState() => _HomeScreenState();
}
class _HomeScreenState extends State<HomeScreen> {
Future futureCall() async {
await Future.delayed(Duration(seconds: 2));
}
#override
Widget build(BuildContext context) {
return FutureBuilder(
future: futureCall(),
builder: (_, dataSnapshot) {
if (dataSnapshot.connectionState == ConnectionState.waiting) {
return Center(child: CircularProgressIndicator());
} else {
Future(() { // Future Callback
showDialog(
context: context,
builder: (context) => AlertDialog(
title: Text('Employee Data'),
content: Text('Do you want to show data?'),
actions: <Widget>[
FlatButton(
onPressed: () =>
Navigator.of(context).pop('No'),
child: Text('NO')),
FlatButton(
onPressed: () =>
Navigator.of(context).pop('Yes'),
child: Text('YES'))
],
));
});
return Container();
}
},
);
}
}
The builder param expects you to return a Widget. showDialog is a Future.
So you can't return that.
You show Dialog on top of other widgets, you can't return it from a build method that is expecting a widget.
What you want can be implemented the following way.
When you receive an error, show a dialog on the UI and return a Container for the builder. Modify your code to this:
if (snapShot.data.runtimeType == http.Response) {
var message =
json.decode(utf8.decode(snapShot.data.bodyBytes));
showDialog(
context: context,
barrierDismissible: false,
builder: (context) {
return AlertDialog(
content: Text(message),
actions: <Widget>[
FlatButton(
child: Text("Ok"),
onPressed: () => null",
)
],
);
});
return Container();
}