c#.net帮助类-数据类型转换 DataTable,DataRow,json

using Newtonsoft.Json;
using System;
using System.Collections.Generic;
using System.Data;
using System.IO;
using System.Linq;
using System.Reflection;
using System.Runtime.Serialization.Json;
using System.Text;
using System.Threading.Tasks;

namespace TService.Code
{
    /// <summary>
    /// 常用数据格式转换帮助类
    /// </summary>
    public class Conversion<T> where T : new()
    {
        #region DataTable转换成实体类

        /// <summary>
        /// 填充对象列表：用DataSet的第一个表填充实体类
        /// </summary>
        /// <param name="ds">DataSet</param>
        /// <returns></returns>
        public List<T> FillModel(DataSet ds)
        {
            if (ds == null || ds.Tables[0] == null || ds.Tables[0].Rows.Count == 0)
            {
                return null;
            }
            else
            {
                return FillModel(ds.Tables[0]);
            }