类型转换

#region List <=> DataTable 互相转换

        /// <summary> 
        /// LINQ返回DataTable类型
        /// </summary> 
        /// <typeparam name="T"> </typeparam> 
        /// <param name="varlist"> </param> 
        /// <returns> </returns> 

        public static DataTable ListToDataTable<T>(IEnumerable<T> varlist)
        {

            DataTable dtReturn = new DataTable();
            // column names 
            PropertyInfo[] oProps = null;
            if (varlist == null)
                return dtReturn;

            foreach (T rec in varlist)
            {
                if (oProps == null)
                {
                    oProps = ((Type)rec.GetType()).GetProperties();
                    foreach (PropertyInfo pi in oProps)
                    {
                        Type colType = pi.PropertyType;
                        if ((colType.IsGenericType) && (colType.GetGenericTypeDefinition()
                             == typeof(Nullable<>)))
                        {
                            colType = colType.GetGenericArguments()[0];
                        }
                        dtReturn.Columns.Add(new DataColumn(pi.Name, colType));
                    }
                }
                DataRow dr = dtReturn.NewRow();
                foreach (PropertyInfo pi in oProps)
                {
                    dr[pi.Name] = pi.GetValue(rec, null) == null ? DBNull.Value : pi.GetValue
                    (rec, null);
                }
                dtReturn.Rows.Add(dr);
            }
            return dtReturn;
        }