How to pop back on previous screen from alert and send there a value?

Question

The questions I'm going to ask are really connected. The idea is pop back on previous screen from alert and send there a value, but as it turned out there are some difficulties with it. I use cool_alert package in these pieces.

1. I can show alert, but how after it pop back on previous screen and send a value?

onPressed: () {
    ...
    _coolAlert(context);
},

if I use the following then why the alert even doesn't show?

onPressed: () {
    ...
    _coolAlert(context);
    Navigator.pop(context, true);
},

where _coolAlert defined as

_coolAlert(Build Context context) {
    CoolAlert.show(
       context: context,
       type: CoolAlertType.success,
       text: "Your transaction was successful!",
       onConfirmBtnTap: () {
           debugPrint('success');
       },
    );
}

the return type of show is Future<dynamic>

3. and finally if change it like this, then why the receiving value on previous screen is null?

_coolAlert(Build Context context) {
  CoolAlert.show(
     context: context,
     type: CoolAlertType.success,
     text: "Your transaction was successful!",
     onConfirmBtnTap: () {
         debugPrint('success');
     },
     Navigator.pop(context, true);
  );
}

Answer 1

There is one more param which is need for this to work.

closeOnConfirmBtnTap: false,

This will allow you to manually call pop method with a value. Here is a sample code

import 'package:cool_alert/cool_alert.dart';
import 'package:flutter/material.dart';

void main() {
  WidgetsFlutterBinding.ensureInitialized();
  runApp(const CoolAlertExample());
}

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

  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      theme: ThemeData.light(
        useMaterial3: true,
      ),
      home: Scaffold(
        appBar: AppBar(title: const Text('Cool Alert Example')),
        body: _HomePage(),
      ),
    );
  }
}

class _HomePage extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return Center(
      child: ElevatedButton(
        onPressed: () async {
          final result = await Navigator.of(context).push<bool?>(
                MaterialPageRoute(
                  builder: (_) => _MyPage(),
                ),
              ) ??
              false;

          print('HomePage: result = $result');
        },
        child: const Text('Next page'),
      ),
    );
  }
}

class _MyPage extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(title: const Text('My Page')),
      body: Center(
        child: ElevatedButton(
          onPressed: () async {
            final navigator = Navigator.of(context);
            final result = await CoolAlert.show(
              context: context,
              type: CoolAlertType.success,
              text: "Your transaction was successful!",
              closeOnConfirmBtnTap: false,
              onConfirmBtnTap: () {
                // return from dialog with success
                debugPrint('success');
                navigator.pop(true);
              },
              onCancelBtnTap: () {
                // return from dialog with cancel
                debugPrint('cancel');
                navigator.pop(false);
              },
            );

            print('returned from cool dialog = $result');

            //return to home page with value retuned from cool dialog.
            navigator.pop<bool>(result);
          },
          child: const Text('Show Alert'),
        ),
      ),
    );
  }
}

Output

flutter: success
flutter: returned from cool dialog = true
flutter: HomePage: result = true