CODEWITHSUNDEEP
flutterdart
Gatonito
Gatonito

Reputation: 2174

How to invoke destructor when launching another page on flutter navigator?

  Navigator.push(
    context,
    MaterialPageRoute(builder: (context) => MyNewPage()),
  )

This loads a new page.

How can I make it such that it calls a destructor on the current page so it can clear its things properly?

I tried adding a dispose method but it isn't executed when I change pages.

Upvotes: 2

Views: 1932

Answers (2)

egjlmn1
egjlmn1

Reputation: 334

You can just use the Navigator.pushReplacement as follows:

Navigator.pushReplacement(
      context, MaterialPageRoute(builder: (BuildContext context) => MyHomePage()));

this will push what you tell it and dispose the previous one once the new one finishes loading.

Upvotes: 0

Simon Sot
Simon Sot

Reputation: 3136

To clear whole current context you can use:

 Navigator.of(context)
    .pushAndRemoveUntil(MaterialPageRoute(builder: (context) =>
     MyNewPage()), (Route<dynamic> route) => false)

Make sure to use a RoutePredicate, that always returns false (Route<dynamic> route) => false. In this situation it removes all of the routes except for the new MyNewPage() route pushed in stack.

In case you need to execute some cleanup function

  • You can invoke it overriding dispose() method: it is called when this object is removed from the tree permanently. Keep in mind, that it is an error to call setState here and make sure to end your method with a call to super.dispose() when overriding it.
@override
void dispose() {
  // Your function.
  super.dispose();
}
  • You can invoke it overriding initState() method of route you are pushing in a stack: It is called when this object is inserted into the tree. If you override this, make sure your method starts with a call to super.initState().
  @override
  void initState() {
    super.initState();
    // Your function.
}
  • If you need a BuildContext for your cleanup function you can use didChangeDependencies(): It is called when a dependency of this State object changes and also immediately after initState, it is safe to use BuildContext here. Subclasses rarely override this method because the framework always calls build after a dependency changes. Some subclasses do override this method because they need to do some expensive work (e.g., network fetches) when their dependencies change, and that work would be too expensive to do for every build.
  @override
  void didChangeDependencies() {
    // Your function.
    super.didChangeDependencies();
  }

Getx package also has variety of ways to insert a Middleware function:

  • Redirect : This function will be called when the page of the called route is being searched for. It takes RouteSettings as a result to redirect to. Or give it null and there will be no redirecting.
GetPage redirect( ) {
  final authService = Get.find<AuthService>();
  return authService.authed.value ? null : RouteSettings(name: '/login')
}
  • onPageCalled : This function will be called when this Page is called before anything created you can use it to change something about the page or give it new page.
GetPage onPageCalled(GetPage page) {
  final authService = Get.find<AuthService>();
  return page.copyWith(title: 'Welcome ${authService.UserName}');
}
  • OnBindingsStart : This function will be called right before the Bindings are initialize. Here you can change Bindings for this page.
List<Bindings> onBindingsStart(List<Bindings> bindings) {
  final authService = Get.find<AuthService>();
  if (authService.isAdmin) {
    bindings.add(AdminBinding());
  }
  return bindings;
}
  • OnPageBuildStart : This function will be called right after the Bindings are initialize. Here you can do something after that you created the bindings and before creating the page widget.
GetPageBuilder onPageBuildStart(GetPageBuilder page) {
  print('bindings are ready');
  return page;
}
  • OnPageBuilt : This function will be called right after the GetPage.page function is called and will give you the result of the function. and take the widget that will be showed.
  • OnPageDispose : This function will be called right after disposing all the related objects (Controllers, views, ...) of the page.

Upvotes: 2

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