Flutter |如何验证时间选择器

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

class MyForm extends StatefulWidget {
  @override
  _MyFormState createState() => _MyFormState();
}

class _MyFormState extends State<MyForm> {
  final _formKey = GlobalKey<FormState>();
  DateTime _selectedTime;

  @override
  Widget build(BuildContext context) {
    return Form(
      key: _formKey,
      child: Column(
        children: [
          TextFormField(
            decoration: InputDecoration(
              labelText: '选择时间',
            ),
            onTap: () {
              DatePicker.showDateTimePicker(
                context,
                showTitleActions: true,
                onChanged: (dateTime) {
                  setState(() {
                    _selectedTime = dateTime;
                  });
                },
              );
            },
            validator: (value) {
              if (_selectedTime == null) {
                return '请选择时间';
              }
              // 进行其他时间验证逻辑，例如判断是否在指定范围内
              return null;
            },
          ),
          ElevatedButton(
            onPressed: () {
              if (_formKey.currentState.validate()) {
                // 表单验证通过，执行提交操作
                // ...
              }
            },
            child: Text('提交'),
          ),
        ],
      ),
    );
  }
}