List<T>转换为DataTable

   今天小姚碰到个问题,有个以前的程序直接调用数据库用dataset和datatable.但是现在想加一层Model层.获取List<T>后赋值给Table时碰到难题.

    本来我觉得这就是个简单的问题,将Table看做一张表,直接循环List后赋值即可.查了下资料才知道自己把DataTable想得太简单了....

     先说后来用到的方法一:

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List<info> infos = Dal.GetInfos(); DataTable dt = new DataTable(); dt.Columns.Add("cName");   foreach(var info in infos) {      DataRow dr = dt.NewRow();      dr["cName"] = info.Name;      dt.Add(dr); }

     再说网上通用的方法二:

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public static class DataTableExtensions    {        /// <summary>        /// 转化一个DataTable        /// </summary>        /// <typeparam name="T"></typeparam>        /// <param name="list"></param>        /// <returns></returns>        public static DataTable ToDataTable<T>(this IEnumerable<T> list)        {            //创建属性的集合            List<PropertyInfo> pList = new List<PropertyInfo>();            //获得反射的入口            Type type = typeof(T);            DataTable dt = new DataTable();            //把所有的public属性加入到集合 并添加DataTable的列            Array.ForEach<PropertyInfo>(type.GetProperties(), p => { pList.Add(p); dt.Columns.Add(p.Name, p.PropertyType); });            foreach (var item in list)            {                //创建一个DataRow实例                DataRow row = dt.NewRow();                //给row 赋值                pList.ForEach(p => row[p.Name] = p.GetValue(item, null));                //加入到DataTable                dt.Rows.Add(row);            }            return dt;        }          /// <summary>        /// DataTable 转换为List 集合        /// </summary>        /// <typeparam name="TResult">类型</typeparam>        /// <param name="dt">DataTable</param>        /// <returns></returns>        public static List<T> ToList<T>(this DataTable dt) where T : class, new()        {            //创建一个属性的列表            List<PropertyInfo> prlist = new List<PropertyInfo>();            //获取TResult的类型实例  反射的入口            Type t = typeof(T);            //获得TResult 的所有的Public 属性 并找出TResult属性和DataTable的列名称相同的属性(PropertyInfo) 并加入到属性列表            Array.ForEach<PropertyInfo>(t.GetProperties(), p => { if (dt.Columns.IndexOf(p.Name) != -1) prlist.Add(p); });            //创建返回的集合            List<T> oblist = new List<T>();              foreach (DataRow row in dt.Rows)            {                //创建TResult的实例                T ob = new T();                //找到对应的数据  并赋值                prlist.ForEach(p => { if (row[p.Name] != DBNull.Value) p.SetValue(ob, row[p.Name], null); });                //放入到返回的集合中.                oblist.Add(ob);            }            return oblist;        }            /// <summary>        /// 将集合类转换成DataTable        /// </summary>        /// <param name="list">集合</param>        /// <returns></returns>        public static DataTable ToDataTableTow(IList list)        {            DataTable result = new DataTable();            if (list.Count > 0)            {                PropertyInfo[] propertys = list[0].GetType().GetProperties();                foreach (PropertyInfo pi in propertys)                {                    result.Columns.Add(pi.Name, pi.PropertyType);                }                  for (int i = 0; i < list.Count; i++)                {                    ArrayList tempList = new ArrayList();                    foreach (PropertyInfo pi in propertys)                    {                        object obj = pi.GetValue(list[i], null);                        tempList.Add(obj);                    }                    object[] array = tempList.ToArray();                    result.LoadDataRow(array, true);                }            }            return result;        }          /**/        /// <summary>        /// 将泛型集合类转换成DataTable        /// </summary>        /// <typeparam name="T">集合项类型</typeparam>        /// <param name="list">集合</param>        /// <returns>数据集(表)</returns>        public static DataTable ToDataTable<T>(IList<T> list)        {            return ToDataTable<T>(list, null);        }          /**/        /// <summary>        /// 将泛型集合类转换成DataTable        /// </summary>        /// <typeparam name="T">集合项类型</typeparam>        /// <param name="list">集合</param>        /// <param name="propertyName">需要返回的列的列名</param>        /// <returns>数据集(表)</returns>        public static DataTable ToDataTable<T>(IList<T> list, params string[] propertyName)        {            List<string> propertyNameList = new List<string>();            if (propertyName != null)                propertyNameList.AddRange(propertyName);              DataTable result = new DataTable();            if (list.Count > 0)            {                PropertyInfo[] propertys = list[0].GetType().GetProperties();                foreach (PropertyInfo pi in propertys)                {                    if (propertyNameList.Count == 0)                    {                        result.Columns.Add(pi.Name, pi.PropertyType);                    }                    else                    {                        if (propertyNameList.Contains(pi.Name))                            result.Columns.Add(pi.Name, pi.PropertyType);                    }                }                  for (int i = 0; i < list.Count; i++)                {                    ArrayList tempList = new ArrayList();                    foreach (PropertyInfo pi in propertys)                    {                        if (propertyNameList.Count == 0)                        {                            object obj = pi.GetValue(list[i], null);                            tempList.Add(obj);                        }                        else                        {                            if (propertyNameList.Contains(pi.Name))                            {                                object obj = pi.GetValue(list[i], null);                                tempList.Add(obj);                            }                        }                    }                    object[] array = tempList.ToArray();                    result.LoadDataRow(array, true);                }            }            return result;        }    }