Navigator.push(
  context,
  MaterialPageRoute(
    builder: (context) => DetailPage(productId: 123),
  ),
);

class DetailPage extends StatelessWidget {
  final int productId;
  DetailPage({required this.productId});

  @override
  Widget build(BuildContext context) {
    return Text("ID ที่รับมา: \$productId");
  }
}

final result = await Navigator.push(
  context,
  MaterialPageRoute(builder: (context) => InputPage()),
);
print("ค่าที่ได้กลับมา: \$result");

Navigator.pop(context, "ข้อมูลจากหน้าใหม่");

import 'package:flutter/material.dart';

void main() => runApp(MyApp());

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(home: HomePage());
  }
}

class HomePage extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(title: Text("หน้าหลัก")),
      body: Center(
        child: ElevatedButton(
          child: Text("กรอกข้อมูล"),
          onPressed: () async {
            final result = await Navigator.push(
              context,
              MaterialPageRoute(builder: (context) => InputPage()),
            );
            ScaffoldMessenger.of(context)
                .showSnackBar(SnackBar(content: Text("ผลลัพธ์: \$result")));
          },
        ),
      ),
    );
  }
}

class InputPage extends StatelessWidget {
  final controller = TextEditingController();

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(title: Text("หน้ากรอกข้อมูล")),
      body: Padding(
        padding: const EdgeInsets.all(16.0),
        child: Column(
          children: [
            TextField(controller: controller),
            SizedBox(height: 10),
            ElevatedButton(
              child: Text("ส่งกลับ"),
              onPressed: () {
                Navigator.pop(context, controller.text);
              },
            ),
          ],
        ),
      ),
    );
  }
}