I have a request from a client who wants to skip one page in opening under some conditions and immediately open another page. However the problem is that when it goes back it wants to always show 2 pages. So page 1 opens page 3 and when I go back from page 3 it goes to page 2 and then station 1. I'm new to flutter and I don't know how to do it.
Use pushReplacement for such Navigation
// In Screen 1
Navigator.pushReplacement(context, Screen3()) // Or Screen2()
// In Screen 3
Navigator.pushReplacement(context, Screen2())
// In Screen 2
Navigator.pushReplacement(context, Screen1())
From page 1 to page 3 your can use
Navigator.push(
context,
MaterialPageRoute(builder: (context) => const Page3()),
Then if you want to go to Page 2 from page 3 use WillPopScope in page 3
return WillPopScope(
onWillPop: (){},
child: Scaffold(
body: Column(
children: [],
),
),
);
Add the above code in page 3. Add condition to check if it should go to Page 1 or 2 in onWillPop and again use navigator.pop or navigator.pushReplacement
I am fairly new to state management in Flutter, and I have an application where the user will be interacting with dialogs, and a dialog may have a button to open another dialog which can result in the following:
https://i.stack.imgur.com/VBSzr.png
As shown, multiple issues arise when more than one is opened at once -- most notably the previous dialog is still visible in the background. So when a user opens a new dialog, is there any method where I can hide the dialog behind it, and when the frontmost dialog closes, show the previous one which is hidden? Thanks in advance.
Use Navigator.pop(context); method to close the dialog on your button's onPressed before opening the second dialog.
And then while closing your second dialog you can reopen your previous dialog.
Example:
showDialog(
context: context,
builder: (context) {
return AlertDialog(
title: Text("Hello World"),
content: Text("This is content"),
actions: [
TextButton(
onPressed: () {
Navigator.pop(context); //Close your current dialog
//TODO:open your second dialog
},
child: Text("Open"))
],
);
});
I would first try to re-think the logic for opening multiple dialogs at the same time.
Maybe there is a quick workaround for that, but if you keep adding more and more dialogs, then it would become a mess.
Since showDialog<T> function returns Future<T?>, you could potentially use await and wait until the first dialog is closed and then open the second one and so on:
bool canContinue = await showDialog<bool>(
context: context,
builder: (context) => YourWidget(),
);
Alternatively, you could pop by using Navigator but as said, this will be visible to the user that something weird is going on (pushing and popping dialogs programatically).
I try to build a flutter app and want to navigate trough the pages.
I build a drawer with a menu with several items to open new pages - that works fine.
onTap: () {
Navigator.of(context).pop();
Navigator.push(
context,
new MaterialPageRoute(
builder: (BuildContext context) => new Page1(),
),
);
},
By pressing on the Page1 menuitem page1 opens fine.
Inside page1 I have a slidable list with "edit" and "details". I open this with
onTap: () {
Navigator.of(context).pop();
Navigator.push(
context,
MaterialPageRoute(
builder: (BuildContext context) => new DetailsPage(),
),
);
},
In the details Page I see all the things i wanna see, but when I press the Back button in the appBar i am back at home screen with closed drawer.
I tried to put onPressed: () => Navigator.pop(context); inside the appBar section but this doesn´t work either.
Now I got what I want by using always Navigator.push but I am sure that this is not right, so that navigator stack gets bigger and bigger.
What I do wrong? Why .pop does not bring me to the last page?
Any ideas?
Thx in advance
Patrick
Just remove the line with the Navigator.of(context).pop();in the Page1 onTap.
you can use pushReplacement in any cases you need to remove current page from stack and route to new page.
Replace the current route of the navigator that most tightly encloses
the given context by pushing the given route and then disposing the
previous route once the new route has finished animating in.
here is the documentation
I'm working on a windows application with flutter desktop, for now, everything seems to work smoothly and with no problems.
But I suspect that I caused a memory leak when using PageView !!
Basically, I have PageViews with 6 pages. One of those pages is a form with a lot of TextEditingController and yea I'm calling dispose() for each TextEditingController and also for all BLoCs I'm using.
Now when The user submits the data and I get a reply from the API that the data was stored successfully I show a success dialog:
return showDialog<void>(
context: context,
barrierDismissible: false,
builder: (BuildContext context) {
return AlertDialog(
title: Text('Succès'),
content: Text(message),
actions: [
FlatButton(
child: Text('Sortie'),
textColor: Colors.white,
color: kColorGreen,
onPressed: () {
Navigator.of(context).pop();
pageController.jumpToPage(2);
// Tried calling dispose here !!
// dispose();
},
),
],
);
},
);
OnPressed: I take the user to another page. And it works BUT when I navigate back to the form page all the form fields are still filled with the old data and the dispose method never gets called !!
I tried calling the dispose method by myself before navigating to another page but no luck !!
So my question is: How can I dispose of all the TextEditingController and the BLoCs present on the form page when navigating out of it?
I cannot understand the reason why someone should use named routes, with Navigator.pushNamed(), instead of the normal way with Navigator.push().
The tutorial page states that:
if we need to navigate to the same screen in many parts of our apps,
this can result in code duplication. In these cases, it can be handy
to define a “named route,” and use the named route for Navigation
Duplication
How will the duplication be generated when using simple routing and how it will can be eliminated with the use of named routes?
I fail to understand what is the difference of
Navigator.push(
context,
MaterialPageRoute(builder: (context) => SecondRoute()),
);
from
Navigator.pushNamed(context, '/second');
in the context of duplication.
Consider you go with Navigator.push() in many widgets:
// inside widget A:
Navigator.push(
context,
MaterialPageRoute(builder: (context) => SecondRoute()),
);
// inside widget B:
Navigator.push(
context,
MaterialPageRoute(builder: (context) => SecondRoute()),
);
// inside widget C:
Navigator.push(
context,
MaterialPageRoute(builder: (context) => SecondRoute()),
);
Now let say you need to change your App and the widget SecondRoute needs to receive a value on it's constructor. Now you have a problem, since you have multiple copies of the same code on several locations, you need to make sure you will update all of those copies, which can be tedious and error prone:
// inside widget A:
Navigator.push(
context,
MaterialPageRoute(builder: (context) => SecondRoute(
title: 'Title A',
)),
);
// inside widget B:
Navigator.push(
context,
MaterialPageRoute(builder: (context) => SecondRoute(
title: 'Title B',
)),
)),
);
// inside widget C:
Navigator.push(
context,
MaterialPageRoute(builder: (context) => SecondRoute(
title: 'Title A', // ERROR! Forgot to change the variable after a copy/paste
)),
)),
);
Now let's consider you go with named routes.
Firstly I would never recommend anyone to actually use the name directly for navigation, but instead use a static variable reference, this way if you need to change it in the future its way simpler and secure, as you can't forget to update it anywhere, like this:
class Routes {
static const String second = '/second';
}
Another way is to have a reference inside the route itself, a static const String inside SecondRoute, so we can use it as SecondRoute.routeName. It's a matter of personal preference IMO.
Then your widgets will navigate using:
// inside widget A:
Navigator.pushNamed(context, Routes.second); // Routes.second is the same as '/second'
// inside widget B:
Navigator.pushNamed(context, Routes.second);
// inside widget C:
Navigator.pushNamed(context, Routes.second);
Now if you need to pass a parameter to SecondRoute upon creation you can do it in a centralized location using the MaterialApp onGenerateRoute, as this tutorial explains in more detail. Your code will be changed to:
// inside widget A:
Navigator.pushNamed(context, Routes.second, arguments: 'Title A');
// inside widget B:
Navigator.pushNamed(context, Routes.second, arguments: 'Title B');
// inside widget C:
// You can still make mistakes here, but the chances are smaller.
Navigator.pushNamed(context, Routes.second, arguments: 'Title C');
MaterialApp(
onGenerateRoute: (settings) {
if (settings.name == Routes.second) {
final String title = settings.arguments;
return MaterialPageRoute(
builder: (context) => SecondRoute(title: title),
);
}
},
);
The amount of duplicated code is decreased, but on the other hand the onGenerateRoute code gets more complex as you make more routes, as all of their creation will be centralized there, so IMHO it's more about a personal preference then a general guideline.
Push and PushNamed have the similar effect, Push will switch to the route you specified while PushNamed will switch to the route with the route name specified.
What the Tutorial page means for duplication is duplication of code not duplication of routes.
For instance, you have a route where you would want to check whether the user is signed in and show the corresponding page
Using Push only:
Page1:
//This is page 1....
RaisedButton(
child: Text('Go to second'),
onPressed: () {
if (user.state = "login") {
Navigator.of(context).push(
MaterialPageRoute(
builder: (context) => SecondPage(),
),
)
}else{
Navigator.of(context).push(
MaterialPageRoute(
builder: (context) => SecondPageAnonymous(),
),
)
}
}
)
....
In another page, Page2, you will need to repeat the same code:
//This is page 2....
RaisedButton(
child: Text('Go to second'),
onPressed: () {
if (user.state = "login") {
Navigator.of(context).push(
MaterialPageRoute(
builder: (context) => SecondPage(),
),
)
}else{
Navigator.of(context).push(
MaterialPageRoute(
builder: (context) => SecondPageAnonymous(),
),
)
}
}
)
....
With PushNamed, you just have to declare it once and you can basically reuse it over and over again.
In your onGenerateRoute:
onGenerateRoute: (settings) {
switch (settings.name) {
case '/':
return MaterialPageRoute(builder: (_) => FirstPage());
case '/second':
if (user.state = "login") {
return MaterialPageRoute(
builder: (_) => SecondPage()
);
}else{
return MaterialPageRoute(
builder: (_) => SecondPageAnonymous()
);
}
default:
return _errorRoute();
}
},
Now in ANY pages in your project, you could do this:
Navigator.of(context).pushNamed('/second')
Without needing to repeat the checking of sign in or even the error handling every time you used it. The obvious benefit is that you can stay consistent throughout the app by preventing duplicate code piece, instead of repeating it again and again.
Now, this however DOES NOT prevent duplicates of routes! There is no different between push and pushNamed in this context!
But since your routes are now named, you can do popUntil('/') easily to go back to the first instance of the route, instead of creating it again or PushReplacementNamed.
The only advantage I can see using Navigate with named routes is to have routes declared inside your MaterialApp, so that developer can only be used assigned routes i.e widgets, pages,
If anyone uses other than that, It will give an error 'onUnknownRoute is called.'
Here is my beginner flutter thoughts:
It makes the code cleaner: Without declaring the routes at the level higher widgets, new screens will appear out of nowhere, in response to anything that happens in the app. It is much easier to understand the navigation skeleton/ structure when you declare the routes together, and even more so at a higher widget, especially for other developers. Of course, this doesn't help with understanding exactly when those routes are actually navigated to, but its a small improvement, and brings us back into the declarative paradigm. The hint provided by the declared routes will help a newer developer understand your navigation flow.
For folks visiting this question in 2022. Flutter actually now recommends not using named routes
Note: Named routes are no longer recommended for most applications. For more information, see Limitations in the navigation overview page.
https://docs.flutter.dev/cookbook/navigation/named-routes
If you use push(), you have to import the file in which SecondRoute is located every time you need to navigate to that screen. This is excessive code duplication for big projects that you need to navigate around the different screens.
If you use pushNamed(), you need to define the routes only once in your MaterialApp. Then, you can navigate to any screen from anywhere without repeating the same thing like you have to with push().
Another big reason to choose PushNamed() over the other one is to be able to build your own navigation system with it. You can decide whether or not routes are available for certain users even before they navigate to the screen.
for understanding why we should use Navigator.pushNamed instead Navigator.push first let's be familiar with Navigator methods. did you ever heart about Navigator.popUntil or Navigator.pushAndRemoveUntil?
we use Navigator.popUntil when we want to pop in the stack to a specific route. if you check the documentation you can find that it's very easy to use these methods with the pushNamed method. also, check all methods in the documentation. when I try to understand routing in flutter this article was very useful for me.
and as a disadvantage, it's very hard to handle parameters in this approach. you should create onGenerateRoute and handle parameters for each route.