[go_router] Remove dependency looks up in GoRouter.of to reduce unwanted rebuild #123570
Description
I'm seeing an odd curiosity when I try out GoRouter.
I suspect it's actually by design, but I'm not sure, so I'm here to clarify this.
flutter doctor -v
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• ONEPLUS A5010 (mobile) • c6a80e66 • android-arm64 • Android 10 (API 29)
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! Doctor found issues in 1 category.
Steps to Reproduce
Download the little demo app from this repo.
Tap on the graphic below to see a gif file displaying the demo app in action.
It's made up of nine State classes. One is called after the other.
Each has buttons so you can go back and forth between them.
The first link below is of my console recording what State objects are built when tapping up to Page 3 in the Demo app:
Up to Page 3
It makes sense, I guess.
It's recursively building all the State object up to the most recent one.
For example, pushing to page 3, the home page, page 1, and page 2 have their build functions called as well.
Guess it's part of sustaining the 'deep link' URL feature particularly desired by web apps.
However, as you progress through the screens in the little demo app, you'll see a different pattern come about.
It's not calling all the build functions from the State objects that proceeded anymore. It still 'rebuilds' the previous State object the router just left, but not before calling the build() functions of 'Page 1' and the 'Home' page:
Up to Page 9
Did you see the pattern in the screenshot above?
Why, with every new route, the last state object is always built again?
Why are the first two State objects in the series always rebuilt again as well??
The sample code is merely how the GoRouter class was set up. The full source code is in the repo.
Sample code
MaterialApp.router(
title: 'Demo App',
routerConfig: GoRouter(
observers: [StateXRouteObserver.routeObserver!],
routes: <RouteBase>[
GoRoute(
path: '/',
builder: (BuildContext context, GoRouterState state) {
return const HomePage();
},
),
GoRoute(
path: '/page1',
builder: (BuildContext context, GoRouterState state) {
return const Page1();
},
),
GoRoute(
path: '/page2',
builder: (BuildContext context, GoRouterState state) {
return const Page2();
},
),
GoRoute(
path: '/page3',
builder: (BuildContext context, GoRouterState state) {
return const Page3();
},
),
GoRoute(
path: '/page4',
builder: (BuildContext context, GoRouterState state) {
return const Page4();
},
),
GoRoute(
path: '/page5',
builder: (BuildContext context, GoRouterState state) {
return const Page5();
},
),
GoRoute(
path: '/page6',
builder: (BuildContext context, GoRouterState state) {
return const Page6();
},
),
GoRoute(
path: '/page7',
builder: (BuildContext context, GoRouterState state) {
return const Page7();
},
),
GoRoute(
path: '/page8',
builder: (BuildContext context, GoRouterState state) {
return const Page8();
},
),
GoRoute(
path: '/page9',
builder: (BuildContext context, GoRouterState state) {
return const Page9();
},
),
],
debugLogDiagnostics: true,
),
);Console
Launching lib\main.dart on sdk gphone x86 64 arm64 in debug mode...
Running Gradle task 'assembleDebug'...
√ Built build\app\outputs\flutter-apk\app-debug.apk.
Installing build\app\outputs\flutter-apk\app-debug.apk...
Debug service listening on ws://127.0.0.1:51290/PcNG7dN7-84=/ws
Syncing files to device sdk gphone x86 64 arm64...
[GoRouter] Full paths for routes:
=> /
=> /page1
=> /page2
=> /page3
=> /page4
=> /page5
=> /page6
=> /page7
=> /page8
=> /page9
[GoRouter] setting initial location null
[GoRouter] Using MaterialApp configuration
I/flutter (14264): ########### build() in HomePage
[GoRouter] pushing /page1
I/flutter (14264): ########### initState() in _Page1State#06558(lifecycle state: created)
I/flutter (14264): ########### didPush() in _Page1State#06558(lifecycle state: initialized)
I/flutter (14264): ########### build() in _Page1State#06558 counter: 0
I/flutter (14264): ########### build() in HomePage
[GoRouter] pushing /page2
I/flutter (14264): ########### didPushNext() in _Page1State#06558
I/flutter (14264): ########### initState() in _Page2State#91bee(lifecycle state: created)
I/flutter (14264): ########### didPush() in _Page2State#91bee(lifecycle state: initialized)
I/flutter (14264): ########### build() in _Page2State#91bee counter: 0
I/flutter (14264): ########### build() in _Page1State#06558 counter: 0
I/flutter (14264): ########### build() in HomePage
[GoRouter] pushing /page3
I/flutter (14264): ########### didPushNext() in _Page2State#91bee
I/flutter (14264): ########### initState() in _Page3State#56793(lifecycle state: created)
I/flutter (14264): ########### didPush() in _Page3State#56793(lifecycle state: initialized)
I/flutter (14264): ########### build() in _Page3State#56793 counter: 0
I/flutter (14264): ########### build() in _Page1State#06558 counter: 0
I/flutter (14264): ########### build() in HomePage
I/flutter (14264): ########### build() in _Page2State#91bee counter: 0
[GoRouter] pushing /page4
I/flutter (14264): ########### didPushNext() in _Page3State#56793
I/flutter (14264): ########### initState() in _Page4State#c2bff(lifecycle state: created)
I/flutter (14264): ########### didPush() in _Page4State#c2bff(lifecycle state: initialized)
I/flutter (14264): ########### build() in _Page4State#c2bff counter: 0
I/flutter (14264): ########### build() in _Page1State#06558 counter: 0
I/flutter (14264): ########### build() in HomePage
I/flutter (14264): ########### build() in _Page3State#56793 counter: 0
[GoRouter] pushing /page5
I/flutter (14264): ########### didPushNext() in _Page4State#c2bff
I/flutter (14264): ########### initState() in _Page5State#ff6fa(lifecycle state: created)
I/flutter (14264): ########### didPush() in _Page5State#ff6fa(lifecycle state: initialized)
I/flutter (14264): ########### build() in _Page5State#ff6fa counter: 0
I/flutter (14264): ########### build() in _Page1State#06558 counter: 0
I/flutter (14264): ########### build() in HomePage
I/flutter (14264): ########### build() in _Page4State#c2bff counter: 0
[GoRouter] pushing /page6
I/flutter (14264): ########### didPushNext() in _Page5State#ff6fa
I/flutter (14264): ########### initState() in _Page6State#e264c(lifecycle state: created)
I/flutter (14264): ########### didPush() in _Page6State#e264c(lifecycle state: initialized)
I/flutter (14264): ########### build() in _Page6State#e264c counter: 0
I/flutter (14264): ########### build() in _Page1State#06558 counter: 0
I/flutter (14264): ########### build() in HomePage
I/flutter (14264): ########### build() in _Page5State#ff6fa counter: 0
[GoRouter] pushing /page7
I/flutter (14264): ########### didPushNext() in _Page6State#e264c
I/flutter (14264): ########### initState() in _Page7State#478c5(lifecycle state: created)
I/flutter (14264): ########### didPush() in _Page7State#478c5(lifecycle state: initialized)
I/flutter (14264): ########### build() in _Page7State#478c5 counter: 0
I/flutter (14264): ########### build() in _Page1State#06558 counter: 0
I/flutter (14264): ########### build() in HomePage
I/flutter (14264): ########### build() in _Page6State#e264c counter: 0
[GoRouter] pushing /page8
I/flutter (14264): ########### didPushNext() in _Page7State#478c5
I/flutter (14264): ########### initState() in _Page8State#47b7f(lifecycle state: created)
I/flutter (14264): ########### didPush() in _Page8State#47b7f(lifecycle state: initialized)
I/flutter (14264): ########### build() in _Page8State#47b7f counter: 0
I/flutter (14264): ########### build() in _Page1State#06558 counter: 0
I/flutter (14264): ########### build() in HomePage
I/flutter (14264): ########### build() in _Page7State#478c5 counter: 0
[GoRouter] pushing /page9
I/flutter (14264): ########### didPushNext() in _Page8State#47b7f
I/flutter (14264): ########### initState() in _Page9State#55102(lifecycle state: created)
I/flutter (14264): ########### didPush() in _Page9State#55102(lifecycle state: initialized)
I/flutter (14264): ########### build() in _Page9State#55102 counter: 0
I/flutter (14264): ########### build() in _Page1State#06558 counter: 0
I/flutter (14264): ########### build() in HomePage
I/flutter (14264): ########### build() in _Page8State#47b7f counter: 0