Question 75330 in Flutter Question posted in
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How fix TypeError on Flutter StatefullWidget Function field?

my error said:

Exception has occurred.
_TypeError (type ‘(ProfileDataset) => SelfProfilePage’ is not a subtype of type ‘(dynamic) => Widget’)

my codes:

import 'package:flutter/material.dart';

class AwaitJumpPage<T> extends StatefulWidget {
  const AwaitJumpPage({
    super.key,
    required this.future,
    required this.callback,
  });
  final Future<T> future;
  final Widget Function(T) callback;

  @override
  State<AwaitJumpPage> createState() => _AwaitJumpPageState<T>();
}

class _AwaitJumpPageState<T> extends State<AwaitJumpPage> {
  @override
  void initState() {
    widget.future.then((value) {
      if (mounted) {
        Navigator.pushReplacement(context, MaterialPageRoute(
          builder: (context) {
            // ignore: unnecessary_cast
            final fun = widget.callback as Widget Function(dynamic);
            return fun(value);
          },
        ));
      }
    });
    super.initState();
  }

  @override
  Widget build(BuildContext context) {
    return const Scaffold(
      body: Center(
        child: CircularProgressIndicator(),
      ),
    );
  }
}

How I using this class:

Navigator.of(context).push(
      MaterialPageRoute(
        builder: (context) {
          return AwaitJumpPage(
            future: [[a future that return ProfileDataset]],
            callback: (data){
              return SelfProfilePage(data);
            }
          );
        },
      ),
    );

My class SelfProfilePage is a widget really.

Can you help me, please?

Tags:

2

Answers


  1. 0

    As I understand your final goal is crate something like that:

    import 'dart:math';

import 'package:flutter/material.dart';

void main() {
  runApp(
    const MaterialApp(
      home: MyApp(),
    ),
  );
}

class MyApp extends StatelessWidget {
  const MyApp({super.key});

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      body: Center(
        child: ElevatedButton(
          onPressed: () => Navigator.of(context).push(
            MaterialPageRoute(
              builder: (context) => AwaitJumpPage(
                builderWithPayload: (context, payload) =>
                    SecondPage(payload: payload),
                future: generateRandomNumber(),
              ),
            ),
          ),
          child: const Text('Click me'),
        ),
      ),
    );
  }

  Future<int> generateRandomNumber() async {
    await Future.delayed(const Duration(seconds: 1));
    return Random().nextInt(100);
  }
}

class SecondPage<T> extends StatelessWidget {
  const SecondPage({
    super.key,
    required this.payload,
  });

  final T payload;

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      body: Center(
        child: Column(
          mainAxisAlignment: MainAxisAlignment.center,
          children: [
            Text('SecondPage result: $payload'),
            ElevatedButton(
              onPressed: () => Navigator.of(context).pop(),
              child: const Text('Back'),
            ),
          ],
        ),
      ),
    );
  }
}

typedef WidgetBuilderWithPayload<T> = Widget Function(
  BuildContext context,
  T payload,
);

class AwaitJumpPage<T> extends StatefulWidget {
  const AwaitJumpPage({
    super.key,
    required this.future,
    required this.builderWithPayload,
  });
  final Future<T> future;
  final WidgetBuilderWithPayload<T> builderWithPayload;

  @override
  State<AwaitJumpPage> createState() => _AwaitJumpPageState<T>();
}

class _AwaitJumpPageState<T> extends State<AwaitJumpPage> {
  @override
  void initState() {
    WidgetsBinding.instance.addPostFrameCallback(_afterLayout);

    super.initState();
  }

  void _afterLayout(_) async {
    T result = await widget.future;
    if (!mounted) return;
    Navigator.pushReplacement(
      context,
      MaterialPageRoute(
        builder: (context) => SecondPage<T>(payload: result),
      ),
    );
  }

  @override
  Widget build(BuildContext context) {
    return const Scaffold(
      body: Center(
        child: CircularProgressIndicator(),
      ),
    );
  }
}

    enter image description here

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  2. 0

    Pass generic type ProfileDataset while calling AwaitJumpPage

    Navigator.of(context).push(
      MaterialPageRoute(
        builder: (context) {
          return AwaitJumpPage<ProfileDataset>(
            future: [[a future that return ProfileDataset]],
            callback: (data){
              return SelfProfilePage(data);
            }
          );
        },
      ),
    );
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