Steps to reproduce Create a page view with a page controller

Can't access `PageController.page` even when `hasClients` is true about flutter HOT 2 OPEN

caseycrogers commented on May 21, 2024 1

Can't access `PageController.page` even when `hasClients` is true

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Comments (2)

caseycrogers commented on May 21, 2024 1

Relatedly, why is PageController.page nullable when it throws if the page isn't available? It feels like an API should either return null if a valid value isn't available or throw-not both?

from flutter.

danagbemava-nc commented on May 21, 2024

Reproducible using the code sample provided above.

complete sample

import 'package:flutter/material.dart';

void main() async {
  runApp(const PageDemo());
}


class PageDemo extends StatefulWidget {
  const PageDemo({super.key});

  @override
  State<PageDemo> createState() => _PageDemoState();
}

class _PageDemoState extends State<PageDemo> {
  final PageController controller = PageController();

  @override
  Widget build(BuildContext context) {
    if (controller.hasClients) {
      print(controller.page);
    }
    return MaterialApp(
      home: Scaffold(
        body: PageView(
          controller: controller,
          children: [
            // Only throws if a builder or sub widget is used here.
            Builder(
              builder: (context) {
                final double currentPage =
                    controller.hasClients ? controller.page ?? -1 : -2;
                return Center(child: Text(currentPage.toString()));
              },
            ),
          ],
        ),
      ),
    );
  }
}

flutter doctor -v

[!] Flutter (Channel stable, 3.19.6, on macOS 14.4.1 23E224 darwin-arm64, locale en-GB)
    • Flutter version 3.19.6 on channel stable at /Users/nexus/dev/sdks/flutter
    ! Warning: `flutter` on your path resolves to /Users/nexus/dev/sdks/flutters/bin/flutter, which is not inside your current Flutter SDK checkout at /Users/nexus/dev/sdks/flutter. Consider adding /Users/nexus/dev/sdks/flutter/bin to the front of your path.
    ! Warning: `dart` on your path resolves to /Users/nexus/dev/sdks/flutters/bin/dart, which is not inside your current Flutter SDK checkout at /Users/nexus/dev/sdks/flutter. Consider adding /Users/nexus/dev/sdks/flutter/bin to the front of your path.
    • Upstream repository https://github.com/flutter/flutter.git
    • Framework revision 54e66469a9 (17 hours ago), 2024-04-17 13:08:03 -0700
    • Engine revision c4cd48e186
    • Dart version 3.3.4
    • DevTools version 2.31.1
    • If those were intentional, you can disregard the above warnings; however it is recommended to use "git" directly to perform update checks and upgrades.

[✓] Android toolchain - develop for Android devices (Android SDK version 34.0.0)
    • Android SDK at /Users/nexus/Library/Android/sdk
    • Platform android-34, build-tools 34.0.0
    • Java binary at: /Users/nexus/Applications/Android Studio.app/Contents/jbr/Contents/Home/bin/java
    • Java version OpenJDK Runtime Environment (build 17.0.7+0-17.0.7b1000.6-10550314)
    • All Android licenses accepted.

[✓] Xcode - develop for iOS and macOS (Xcode 15.3)
    • Xcode at /Applications/Xcode-15.3.0.app/Contents/Developer
    • Build 15E204a
    • CocoaPods version 1.14.3

[✓] Chrome - develop for the web
    • Chrome at /Applications/Google Chrome.app/Contents/MacOS/Google Chrome

[✓] Android Studio (version 2023.1)
    • Android Studio at /Users/nexus/Applications/Android Studio.app/Contents
    • Flutter plugin can be installed from:
      🔨 https://plugins.jetbrains.com/plugin/9212-flutter
    • Dart plugin can be installed from:
      🔨 https://plugins.jetbrains.com/plugin/6351-dart
    • Java version OpenJDK Runtime Environment (build 17.0.7+0-17.0.7b1000.6-10550314)

[✓] IntelliJ IDEA Ultimate Edition (version 2023.2.5)
    • IntelliJ at /Users/nexus/Applications/IntelliJ IDEA Ultimate.app
    • Flutter plugin version 77.2.2
    • Dart plugin version 232.10286

[✓] VS Code (version 1.88.1)
    • VS Code at /Applications/Visual Studio Code.app/Contents
    • Flutter extension version 3.86.0

[✓] Connected device (4 available)
    • Nexus (mobile)       • 00008020-001875E83A38002E • ios            • iOS 17.4.1 21E236
    • Dean’s iPad (mobile) • 00008103-000825C811E3401E • ios            • iOS 17.4.1 21E236
    • macOS (desktop)      • macos                     • darwin-arm64   • macOS 14.4.1 23E224 darwin-arm64
    • Chrome (web)         • chrome                    • web-javascript • Google Chrome 124.0.6367.60

[✓] Network resources
    • All expected network resources are available.

! Doctor found issues in 1 category.

[✓] Flutter (Channel master, 3.22.0-13.0.pre.38, on macOS 14.4.1 23E224 darwin-arm64, locale en-GB)
    • Flutter version 3.22.0-13.0.pre.38 on channel master at /Users/nexus/dev/sdks/flutters
    • Upstream repository https://github.com/flutter/flutter.git
    • Framework revision 86135b7774 (10 hours ago), 2024-04-17 20:08:36 -0700
    • Engine revision 20638b75c8
    • Dart version 3.5.0 (build 3.5.0-71.0.dev)
    • DevTools version 2.35.0-dev.8

[✓] Android toolchain - develop for Android devices (Android SDK version 34.0.0)
    • Android SDK at /Users/nexus/Library/Android/sdk
    • Platform android-34, build-tools 34.0.0
    • Java binary at: /Users/nexus/Applications/Android Studio.app/Contents/jbr/Contents/Home/bin/java
    • Java version OpenJDK Runtime Environment (build 17.0.7+0-17.0.7b1000.6-10550314)
    • All Android licenses accepted.

[✓] Xcode - develop for iOS and macOS (Xcode 15.3)
    • Xcode at /Applications/Xcode-15.3.0.app/Contents/Developer
    • Build 15E204a
    • CocoaPods version 1.14.3

[✓] Chrome - develop for the web
    • Chrome at /Applications/Google Chrome.app/Contents/MacOS/Google Chrome

[✓] Android Studio (version 2023.1)
    • Android Studio at /Users/nexus/Applications/Android Studio.app/Contents
    • Flutter plugin can be installed from:
      🔨 https://plugins.jetbrains.com/plugin/9212-flutter
    • Dart plugin can be installed from:
      🔨 https://plugins.jetbrains.com/plugin/6351-dart
    • Java version OpenJDK Runtime Environment (build 17.0.7+0-17.0.7b1000.6-10550314)

[✓] IntelliJ IDEA Ultimate Edition (version 2023.2.5)
    • IntelliJ at /Users/nexus/Applications/IntelliJ IDEA Ultimate.app
    • Flutter plugin version 77.2.2
    • Dart plugin version 232.10286

[✓] VS Code (version 1.88.1)
    • VS Code at /Applications/Visual Studio Code.app/Contents
    • Flutter extension version 3.86.0

[✓] Connected device (5 available)
    • Nexus (mobile)                  • 00008020-001875E83A38002E • ios            • iOS 17.4.1 21E236
    • Dean’s iPad (mobile)            • 00008103-000825C811E3401E • ios            • iOS 17.4.1 21E236
    • macOS (desktop)                 • macos                     • darwin-arm64   • macOS 14.4.1 23E224 darwin-arm64
    • Mac Designed for iPad (desktop) • mac-designed-for-ipad     • darwin         • macOS 14.4.1 23E224 darwin-arm64
    • Chrome (web)                    • chrome                    • web-javascript • Google Chrome 124.0.6367.60

[✓] Network resources
    • All expected network resources are available.

• No issues found!

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Can't access `PageController.page` even when `hasClients` is true about flutter HOT 2 OPEN

Comments (2)

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