firka/flutter
firka/flutter
5
Fork 0
Code Issues Pull Requests Packages Projects Releases Wiki Activity

Improved error message when PageController is not attached to PageView (#162422)

Browse Source 
Fixes https://github.com/flutter/flutter/issues/138945
- Added asserts for jumpToPage and animateToPage methods in
PageController (https://github.com/flutter/flutter/issues/138945)
- Covered by tests

<!--
Thanks for filing a pull request!
Reviewers are typically assigned within a week of filing a request.
To learn more about code review, see our documentation on Tree Hygiene:
https://github.com/flutter/flutter/blob/main/docs/contributing/Tree-hygiene.md
-->

*Replace this paragraph with a description of what this PR is changing
or adding, and why. Consider including before/after screenshots.*

*List which issues are fixed by this PR. You must list at least one
issue. An issue is not required if the PR fixes something trivial like a
typo.*

*If you had to change anything in the [flutter/tests] repo, include a
link to the migration guide as per the [breaking change policy].*

## Pre-launch Checklist

- [x] I read the [Contributor Guide] and followed the process outlined
there for submitting PRs.
- [x] I read the [Tree Hygiene] wiki page, which explains my
responsibilities.
- [x] I read and followed the [Flutter Style Guide], including [Features
we expect every widget to implement].
- [x] I signed the [CLA].
- [x] I listed at least one issue that this PR fixes in the description
above.
- [ ] I updated/added relevant documentation (doc comments with `///`).
- [x] I added new tests to check the change I am making, or this PR is
[test-exempt].
- [ ] I followed the [breaking change policy] and added [Data Driven
Fixes] where supported.
- [x] All existing and new tests are passing.

If you need help, consider asking for advice on the #hackers-new channel
on [Discord].

<!-- Links -->
[Contributor Guide]:
https://github.com/flutter/flutter/blob/main/docs/contributing/Tree-hygiene.md#overview
[Tree Hygiene]:
https://github.com/flutter/flutter/blob/main/docs/contributing/Tree-hygiene.md
[test-exempt]:
https://github.com/flutter/flutter/blob/main/docs/contributing/Tree-hygiene.md#tests
[Flutter Style Guide]:
https://github.com/flutter/flutter/blob/main/docs/contributing/Style-guide-for-Flutter-repo.md
[Features we expect every widget to implement]:
https://github.com/flutter/flutter/blob/main/docs/contributing/Style-guide-for-Flutter-repo.md#features-we-expect-every-widget-to-implement
[CLA]: https://cla.developers.google.com/
[flutter/tests]: https://github.com/flutter/tests
[breaking change policy]:
https://github.com/flutter/flutter/blob/main/docs/contributing/Tree-hygiene.md#handling-breaking-changes
[Discord]:
https://github.com/flutter/flutter/blob/main/docs/contributing/Chat.md
[Data Driven Fixes]:
https://github.com/flutter/flutter/blob/main/docs/contributing/Data-driven-Fixes.md
This commit is contained in:
Paulik8 2025-02-10 18:39:06 +01:00 committed by GitHub
parent 1d766ed8d9
commit 78e5d7995c
No known key found for this signature in database
GPG Key ID: B5690EEEBB952194
2 changed files with 171 additions and 0 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

14
packages/flutter/lib/src/widgets/page_view.dart
View File

@ -185,11 +185,22 @@ class PageController extends ScrollController {
return position.page;
}
bool _debugCheckPageControllerAttached() {
assert(positions.isNotEmpty, 'PageController is not attached to a PageView.');
assert(
positions.length == 1,
'Multiple PageViews are attached to '
'the same PageController.',
);
return true;
}
/// Animates the controlled [PageView] from the current page to the given page.
///
/// The animation lasts for the given duration and follows the given curve.
/// The returned [Future] resolves when the animation completes.
Future<void> animateToPage(int page, {required Duration duration, required Curve curve}) {
assert(_debugCheckPageControllerAttached());
final _PagePosition position = this.position as _PagePosition;
if (position._cachedPage != null) {
position._cachedPage = page.toDouble();
@ -213,6 +224,7 @@ class PageController extends ScrollController {
/// Jumps the page position from its current value to the given value,
/// without animation, and without checking if the new value is in range.
void jumpToPage(int page) {
assert(_debugCheckPageControllerAttached());
final _PagePosition position = this.position as _PagePosition;
if (position._cachedPage != null) {
position._cachedPage = page.toDouble();
@ -332,6 +344,7 @@ class _PagePosition extends ScrollPositionWithSingleContext implements PageMetri
final int initialPage;
double _pageToUseOnStartup;
// When the viewport has a zero-size, the `page` can not
// be retrieved by `getPageFromPixels`, so we need to cache the page
// for use when resizing the viewport to non-zero next time.
@ -362,6 +375,7 @@ class _PagePosition extends ScrollPositionWithSingleContext implements PageMetri
@override
double get viewportFraction => _viewportFraction;
double _viewportFraction;
set viewportFraction(double value) {
if (_viewportFraction == value) {
return;

157
packages/flutter/test/widgets/page_view_test.dart
View File

@ -1403,6 +1403,163 @@ void main() {
});
});
group('Asserts in jumpToPage and animateToPage methods works properly', () {
Widget createPageView([PageController? controller]) {
return MaterialApp(
home: Scaffold(
body: PageView(
controller: controller,
children: <Widget>[
Container(color: Colors.red),
Container(color: Colors.green),
Container(color: Colors.blue),
],
),
),
);
}
group('One pageController is attached to multiple PageViews', () {
Widget createMultiplePageViews(PageController controller) {
return MaterialApp(
home: Scaffold(
body: Column(
children: <Widget>[
Expanded(
child: PageView(
controller: controller,
children: <Widget>[
Container(color: Colors.red),
Container(color: Colors.green),
Container(color: Colors.blue),
],
),
),
Expanded(
child: PageView(
controller: controller,
children: <Widget>[
Container(color: Colors.orange),
Container(color: Colors.purple),
Container(color: Colors.yellow),
],
),
),
],
),
),
);
}
testWidgets(
'animateToPage assertion is working properly when pageController is attached to multiple PageViews',
(WidgetTester tester) async {
final PageController controller = PageController();
addTearDown(controller.dispose);
await tester.pumpWidget(createMultiplePageViews(controller));
expect(
() => controller.animateToPage(
2,
duration: const Duration(milliseconds: 300),
curve: Curves.ease,
),
throwsA(
isAssertionError.having(
(AssertionError error) => error.message,
'message',
equals(
'Multiple PageViews are attached to '
'the same PageController.',
),
),
),
);
},
);
testWidgets(
'jumpToPage assertion is working properly when pageController is attached to multiple PageViews',
(WidgetTester tester) async {
final PageController controller = PageController();
addTearDown(controller.dispose);
await tester.pumpWidget(createMultiplePageViews(controller));
expect(
() => controller.jumpToPage(2),
throwsA(
isAssertionError.having(
(AssertionError error) => error.message,
'message',
equals(
'Multiple PageViews are attached to '
'the same PageController.',
),
),
),
);
},
);
});
group('PageController is attached or is not attached to PageView', () {
testWidgets('Assert behavior of animateToPage works properly', (WidgetTester tester) async {
final PageController controller = PageController();
addTearDown(controller.dispose);
// pageController is not attached to PageView
await tester.pumpWidget(createPageView());
expect(
() => controller.animateToPage(
2,
duration: const Duration(milliseconds: 300),
curve: Curves.ease,
),
throwsA(
isAssertionError.having(
(AssertionError error) => error.message,
'message',
equals('PageController is not attached to a PageView.'),
),
),
);
// pageController is attached to PageView
await tester.pumpWidget(createPageView(controller));
expect(
() => controller.animateToPage(
2,
duration: const Duration(milliseconds: 300),
curve: Curves.ease,
),
returnsNormally,
);
});
testWidgets('Assert behavior of jumpToPage works properly', (WidgetTester tester) async {
final PageController controller = PageController();
addTearDown(controller.dispose);
// pageController is not attached to PageView
await tester.pumpWidget(createPageView());
expect(
() => controller.jumpToPage(2),
throwsA(
isAssertionError.having(
(AssertionError error) => error.message,
'message',
equals('PageController is not attached to a PageView.'),
),
),
);
// pageController is attached to PageView
await tester.pumpWidget(createPageView(controller));
expect(() => controller.jumpToPage(2), returnsNormally);
});
});
});
testWidgets(
'Get the page value before the content dimension is determined,do not throw an assertion and return null',
(WidgetTester tester) async {