如何在构建Flutter ListView的过程中测试json属性是否存在

import 'dart:convert';

import 'package:flutter/material.dart';

void main() {
  runApp(MyApp());
}

class MyApp extends StatelessWidget {
  final String jsonStr = '''
    [
      {"name": "John", "age": 25},
      {"name": "Jane"}
    ]
  ''';

  @override
  Widget build(BuildContext context) {
    List<Map<String, dynamic>> jsonData = json.decode(jsonStr);

    return MaterialApp(
      home: Scaffold(
        appBar: AppBar(
          title: Text('ListView Test'),
        ),
        body: ListView.builder(
          itemCount: jsonData.length,
          itemBuilder: (context, index) {
            final person = jsonData[index];
            final name = person.containsKey('name') ? person['name'] : 'Unknown';
            final age = person.containsKey('age') ? person['age'] : 'Unknown';

            return ListTile(
              title: Text('Name: $name'),
              subtitle: Text('Age: $age'),
            );
          },
        ),
      ),
    );
  }
}