Force Flutter navigator to reload state when popping
FlutterDartNavigationFlutter Problem Overview
I have one StatefulWidget
in Flutter with button, which navigates me to another StatefulWidget
using Navigator.push()
. On second widget I'm changing global state (some user preferences). When I get back from second widget to first, using Navigator.pop()
the first widget is in old state, but I want to force it's reload. Any idea how to do this? I have one idea but it looks ugly:
- pop to remove second widget (current one)
- pop again to remove first widget (previous one)
- push first widget (it should force redraw)
Flutter Solutions
Solution 1 - Flutter
There's a couple of things you could do here. @Mahi's answer while correct could be a little more succinct and actually use push rather than showDialog as the OP was asking about. This is an example that uses Navigator.push
:
import 'package:flutter/material.dart';
class SecondPage extends StatelessWidget {
@override
Widget build(BuildContext context) {
return Container(
color: Colors.green,
child: Column(
children: <Widget>[
RaisedButton(
onPressed: () => Navigator.pop(context),
child: Text('back'),
),
],
),
);
}
}
class FirstPage extends StatefulWidget {
@override
State<StatefulWidget> createState() => new FirstPageState();
}
class FirstPageState extends State<FirstPage> {
Color color = Colors.white;
@override
Widget build(BuildContext context) {
return new Container(
color: color,
child: Column(
children: <Widget>[
RaisedButton(
child: Text("next"),
onPressed: () async {
final value = await Navigator.push(
context,
MaterialPageRoute(
builder: (context) => SecondPage()),
),
);
setState(() {
color = color == Colors.white ? Colors.grey : Colors.white;
});
},
),
],
),
);
}
}
void main() => runApp(
MaterialApp(
builder: (context, child) => SafeArea(child: child),
home: FirstPage(),
),
);
However, there's another way to do this that might fit your use-case well. If you're using the global
as something that affects the build of your first page, you could use an InheritedWidget to define your global user preferences, and each time they are changed your FirstPage will rebuild. This even works within a stateless widget as shown below (but should work in a stateful widget as well).
An example of inheritedWidget in flutter is the app's Theme, although they define it within a widget instead of having it directly building as I have here.
import 'package:flutter/material.dart';
import 'package:meta/meta.dart';
class SecondPage extends StatelessWidget {
@override
Widget build(BuildContext context) {
return Container(
color: Colors.green,
child: Column(
children: <Widget>[
RaisedButton(
onPressed: () {
ColorDefinition.of(context).toggleColor();
Navigator.pop(context);
},
child: new Text("back"),
),
],
),
);
}
}
class ColorDefinition extends InheritedWidget {
ColorDefinition({
Key key,
@required Widget child,
}): super(key: key, child: child);
Color color = Colors.white;
static ColorDefinition of(BuildContext context) {
return context.inheritFromWidgetOfExactType(ColorDefinition);
}
void toggleColor() {
color = color == Colors.white ? Colors.grey : Colors.white;
print("color set to $color");
}
@override
bool updateShouldNotify(ColorDefinition oldWidget) =>
color != oldWidget.color;
}
class FirstPage extends StatelessWidget {
@override
Widget build(BuildContext context) {
var color = ColorDefinition.of(context).color;
return new Container(
color: color,
child: new Column(
children: <Widget>[
new RaisedButton(
child: new Text("next"),
onPressed: () {
Navigator.push(
context,
new MaterialPageRoute(builder: (context) => new SecondPage()),
);
}),
],
),
);
}
}
void main() => runApp(
new MaterialApp(
builder: (context, child) => new SafeArea(
child: new ColorDefinition(child: child),
),
home: new FirstPage(),
),
);
If you use inherited widget you don't have to worry about watching for the pop of the page you pushed, which will work for basic use-cases but may end up having problems in a more complex scenario.
Solution 2 - Flutter
Short answer:
Use this in 1st page:
Navigator.pushNamed(context, '/page2').then((_) => setState(() {}));
and this in 2nd page:
Navigator.pop(context);
There are 2 things, passing data from
-
1st Page to 2nd
Use this in 1st page
// sending "Foo" from 1st Navigator.push(context, MaterialPageRoute(builder: (_) => Page2("Foo")));
Use this in 2nd page.
class Page2 extends StatelessWidget { final String string; Page2(this.string); // receiving "Foo" in 2nd ... }
-
2nd Page to 1st
Use this in 2nd page
// sending "Bar" from 2nd Navigator.pop(context, "Bar");
Use this in 1st page, it is the same which was used earlier but with little modification.
// receiving "Bar" in 1st String received = await Navigator.push(context, MaterialPageRoute(builder: (_) => Page2("Foo")));
Solution 3 - Flutter
For me this seems to work:
Navigator.of(context).pushNamed("/myRoute").then((value) => setState(() {}));
Then simply call Navigator.pop()
in the child.
Solution 4 - Flutter
The Easy Trick is to use the Navigator.pushReplacement method
Page 1
Navigator.pushReplacement(
context,
MaterialPageRoute(
builder: (context) => Page2(),
),
);
Page 2
Navigator.pushReplacement(
context,
MaterialPageRoute(
builder: (context) => Page1(),
),
);
Solution 5 - Flutter
You can use pushReplacement and specify the new Route
Solution 6 - Flutter
Simply add .then((value) { setState(() {});
after Navigator.push on page1() just like below:
Navigator.push(context,MaterialPageRoute(builder: (context) => Page2())).then((value) { setState(() {});
Now when you use Navigator.pop(context)
from page2 your page1 rebuild itself
Solution 7 - Flutter
my solution went by adding a function parameter on SecondPage, then received the reloading function which is being done from FirstPage, then executed the function before the Navigator.pop(context) line.
FirstPage
refresh() {
setState(() {
//all the reload processes
});
}
then on pushing to the next page...
Navigator.push(context, new MaterialPageRoute(builder: (context) => new SecondPage(refresh)),);
SecondPage
final Function refresh;
SecondPage(this.refresh); //constructor
then on before the navigator pop line,
widget.refresh(); // just refresh() if its statelesswidget
Navigator.pop(context);
Everything that needs to be reloaded from the previous page should be updated after the pop.
Solution 8 - Flutter
This work really good, i got from this doc from flutter page: flutter doc
I defined the method to control navigation from first page.
_navigateAndDisplaySelection(BuildContext context) async {
final result = await Navigator.push(
context,
MaterialPageRoute(builder: (context) => AddDirectionPage()),
);
//below you can get your result and update the view with setState
//changing the value if you want, i just wanted know if i have to
//update, and if is true, reload state
if (result) {
setState(() {});
}
}
So, i call it in a action method from a inkwell, but can be called also from a button:
onTap: () {
_navigateAndDisplaySelection(context);
},
And finally in the second page, to return something (i returned a bool, you can return whatever you want):
onTap: () {
Navigator.pop(context, true);
}
Solution 9 - Flutter
onTapFunction(BuildContext context) async {
final reLoadPage = await Navigator.push(
context,
MaterialPageRoute(builder: (context) => IdDetailsScreen()),
);
if (reLoadPage) {
setState(() {});
}
}
Now while doing Navigator.pop
from second page to come back to first page just return some value which in my case if bool
type
onTap: () {
Navigator.pop(context, true);
}
Solution 10 - Flutter
Put this where you're pushing to second screen (inside an async function)
Function f;
f= await Navigator.pushNamed(context, 'ScreenName');
f();
Put this where you are popping
Navigator.pop(context, () {
setState(() {});
});
The setState
is called inside the pop
closure to update the data.
Solution 11 - Flutter
You can pass back a dynamic result
when you are popping the context and then call the setState((){})
when the value is true
otherwise just leave the state as it is.
I have pasted some code snippets for your reference.
handleClear() async {
try {
var delete = await deleteLoanWarning(
context,
'Clear Notifications?',
'Are you sure you want to clear notifications. This action cannot be undone',
);
if (delete.toString() == 'true') {
//call setState here to rebuild your state.
}
} catch (error) {
print('error clearing notifications' + error.toString());
}
}
Future<bool> deleteLoanWarning(BuildContext context, String title, String msg) async {
return await showDialog<bool>(
context: context,
child: new AlertDialog(
title: new Text(
title,
style: new TextStyle(fontWeight: fontWeight, color: CustomColors.continueButton),
textAlign: TextAlign.center,
),
content: new Text(
msg,
textAlign: TextAlign.justify,
),
actions: <Widget>[
new Container(
decoration: boxDecoration(),
child: new MaterialButton(
child: new Text('NO',),
onPressed: () {
Navigator.of(context).pop(false);
},
),
),
new Container(
decoration: boxDecoration(),
child: new MaterialButton(
child: new Text('YES', ),
onPressed: () {
Navigator.of(context).pop(true);
},
),
),
],
),
) ??
false;
}
Regards, Mahi
Solution 12 - Flutter
I had a similar issue.
Please try this out:
In the First Page:
Navigator.push( context, MaterialPageRoute( builder: (context) => SecondPage()), ).then((value) => setState(() {}));
After you pop back from SecondPage() to FirstPage() the "then" statement will run and refresh the page.
Solution 13 - Flutter
Needed to force rebuild of one of my stateless widgets. Did't want to use stateful. Came up with this solution:
await Navigator.of(context).pushNamed(...);
ModalRoute.of(enclosingWidgetContext);
Note that context and enclosingWidgetContext could be the same or different contexts. If, for example, you push from inside StreamBuilder, they would be different.
We don't do anything here with ModalRoute. The act of subscribing alone is enough to force rebuild.
Solution 14 - Flutter
If you are using an alert dialog then you can use a Future that completes when the dialog is dismissed. After the completion of the future you can force widget to reload the state.
First page
onPressed: () async {
await showDialog(
context: context,
builder: (BuildContext context) {
return AlertDialog(
....
);
}
);
setState(() {});
}
In Alert dialog
Navigator.of(context).pop();
Solution 15 - Flutter
This simple code worked for me to go to the root and reload the state:
...
onPressed: () {
Navigator.of(context).pushNamedAndRemoveUntil('/', ModalRoute.withName('/'));
},
...
Solution 16 - Flutter
For me worked:
...
onPressed: (){pushUpdate('/somePageName');}
...
pushUpdate (string pageName) async { //in the same class
await pushPage(context, pageName);
setState(() {});
}
//---------------------------------------------
//general sub
pushPage (context, namePage) async {
await Navigator.pushNamed(context, namePage);
}
In this case doesn't matter how you pop (with button in UI or "back" in android) the update will be done.
Solution 17 - Flutter
In flutter 2.5.2 this is worked for me also it works for updating a list
Navigator.push(
context,
MaterialPageRoute(
builder: (context) => SecondPage()))
.then((value) => setState(() {}));
then in the second page I just code this
Navigator.pop(context);
I have a ListView
in fist page which is display a list[]
data, the second page was updating the data for my list[]
so the above code works for me.
Solution 18 - Flutter
In short, you should make the widget watch the state. You need state management for this.
My method is based on Provider explained in Flutter Architecture Samples as well as Flutter Docs. Please refer to them for more concise explanation but more or less the steps are :
- Define your state model with states that the widget needs to observe.
You could have multiple states say data
and isLoading
, to wait for some API process. The model itself extends ChangeNotifier
.
- Wrap the widgets that depend on those states with watcher class.
This could be Consumer
or Selector
.
-
When you need to "reload", you basically update those states and broadcast the changes.
For state model the class would look more or less as follows. Pay attention to notifyListeners
which broadcasts the changes.
class DataState extends ChangeNotifier{
bool isLoading;
Data data;
Future loadData(){
isLoading = true;
notifyListeners();
service.get().then((newData){
isLoading = false;
data = newData;
notifyListeners();
});
}
}
Now for the widget. This is going to be very much a skeleton code.
return ChangeNotifierProvider(
create: (_) => DataState()..loadData(),
child: ...{
Selector<DataState, bool>(
selector: (context, model) => model.isLoading,
builder: (context, isLoading, _) {
if (isLoading) {
return ProgressBar;
}
return Container(
child: Consumer<DataState>(builder: (context, dataState, child) {
return WidgetData(...);
}
));
},
),
}
);
Instance of the state model is provided by ChangeNotifierProvider. Selector and Consumer watch the states, each for isLoading
and data
respectively. There is not much difference between them but personally how you use them would depend on what their builders provide. Consumer provides access to the state model so calling loadData
is simpler for any widgets directly underneath it.
If not then you can use Provider.of
. If we'd like to refresh the page upon return from the second screen then we can do something like this:
await Navigator.push(context,
MaterialPageRoute(
builder: (_) {
return Screen2();
));
Provider.of<DataState>(context, listen: false).loadData();
Solution 19 - Flutter
Very simply use "then" after you push, when navigator pops back it will fire setState and the view will refresh.
Navigator.push(blabla...).then((value) => setState(() {}))
Solution 20 - Flutter
// Push to second screen
await Navigator.push(
context,
CupertinoPageRoute(
builder: (context) => SecondScreen(),
),
);
// Call build method to update any changes
setState(() {});
Solution 21 - Flutter
navigtor.pop(context,(){
setState((){}
}))
This will pop the screen and refresh the previous screen