我想在页面视图中显示数据库中的数据，滑动屏幕，如user1_name -> user1_age -> user2_name -> user2_age ->等，以显示来自数据库的所有数据，但我的代码只显示第一个用户数据（只有一个）。在gridview中显示数据库的所有数据。我正在添加代码，请帮助我修改什么：

import 'package:flutter/material.dart';
import 'package:flutter/src/widgets/framework.dart';
import 'package:flutter/src/widgets/placeholder.dart';
import 'package:http/http.dart' as http;
import 'dart:convert';
import 'package:student/student_pages/student_detail.dart';
import '../utils/constants.dart';

String website = Constants.website;

class UserDetail extends StatefulWidget {
  final String subjectId;
  const UserDetail({super.key, required this.userId});

  @override
  State<UserDetail> createState() =>
      _UserDetailState();
}

class _UserDetailState extends State<UserDetail> {
  get userId => widget.userId;

  get itemCount => null;
  Future<List> getUserData() async {
    String url = '$website/get_user_data.php';
    var data = {'user_id': userId};
    var response = await http.post(Uri.parse(url), body: data);
    var userDetail= jsonDecode(response.body.toString());
    return userDetail;
  }

  PageController pageController = PageController();
  @override
  Widget build(BuildContext context) {
      return Scaffold(
      appBar: AppBar(
        title: const Text('User Detail'),
        ),
      body: SafeArea(
        child: Column(
          children: <Widget>[
            Expanded(
              child: Container(
                padding: const EdgeInsets.all(10),
                alignment: Alignment.center,
                margin: EdgeInsets.all(10),
                width: double.infinity,
                decoration: BoxDecoration(
                color: Colors.red,
                  borderRadius:
                      BorderRadius.circular(20), //border corner radius
                  boxShadow: [
                    BoxShadow(
                      color: Colors.grey.withOpacity(0.5), //color of shadow
                      spreadRadius: 5, //spread radius
                      blurRadius: 7, // blur radius
                      offset: Offset(0, 2), // changes position of shadow
                    ),
                  ],
                ),

                child: Text(
                  'Swip left, right',
                  style: TextStyle(
                    color: Colors.white,
                    fontWeight: FontWeight.bold,
                    fontSize: 15,
                  ),
                ),
              ),
            ),
            Expanded(
              flex: 8,
              child: FutureBuilder<List<dynamic>>(
                future: getUserData(),
                builder: (context, snapshot) {
                  if (snapshot.hasData) {
                    return Padding(
                      padding: const EdgeInsets.all(8.0),
                      child: PageView.builder(
                        itemCount: snapshot.data!.length,
                        itemBuilder: (context, index) {
                          var userName = snapshot.data![index]['user_name'];
                          var userAge = snapshot.data![index]['user_age'];
                          return PageView(
                            pageSnapping: true,
                            controller: pageController,
                            children: [
                              Container(
                                child: Text(
                                  "$index:- $userName,",
                                ),
                              ),
                              Container(
                                child: Text(
                                  '$userAge',
                                ),
                              ),
                            ],
                          );
                        },
                      ),
                    );
                  }
                  return Center(
                    child: CircularProgressIndicator(),
                  );
                },
              ),
            ),

           
          ],
        ),
      ),
    );
  }
}