如何在使用FileHelpers时将CSV空字符串作为NULL加载到SQL Server中？

using FileHelpers;
using System;
using System.Collections.Generic;
using System.Data.SqlClient;

namespace FileHelpersExample
{
    // 定义CSV映射的对象类型
    [DelimitedRecord(",")]
    public class Person
    {
        [FieldNullValue(null)] // 将空字符串映射为NULL
        public string Name;

        [FieldNullValue(null)]
        public string Age;

        [FieldNullValue(null)]
        public string Email;
    }

    public class Program
    {
        static void Main(string[] args)
        {
            var engine = new FileHelperEngine<Person>(); // 创建FileHelpers引擎对象
            var records = engine.ReadFile("path/to/your/csv/file.csv"); // 读取CSV文件并转换为对象集合

            foreach (var record in records)
            {
                // 检查需要映射的属性是否为空字符串，如果是则设置为NULL
                if (record.Name == "")
                    record.Name = null;
                
                if (record.Age == "")
                    record.Age = null;

                if (record.Email == "")
                    record.Email = null;
            }

            // 将对象集合插入到SQL Server中的数据库表中
            using (var connection = new SqlConnection("your_connection_string"))
            {
                connection.Open();
                
                foreach (var record in records)
                {
                    // 执行插入操作，将record的属性映射到对应的数据库表字段
                    var command = new SqlCommand("INSERT INTO YourTable (Name, Age, Email) VALUES (@Name, @Age, @Email)", connection);
                    command.Parameters.AddWithValue("@Name", record.Name);
                    command.Parameters.AddWithValue("@Age", record.Age);
                    command.Parameters.AddWithValue("@Email", record.Email);
                    command.ExecuteNonQuery();
                }
            }
        }
    }
}