C#泛型轉換函數

 public static IList <T> ConvertToList< T>(DataTable dt) where T : new()
        {
            List<T > list = new List< T>();
            T model = default (T);
            foreach (DataRow dr in dt.Rows)
            {
                model = Activator.CreateInstance<T >();
                PropertyInfo[] propertys = model.GetType().GetProperties();
                foreach (PropertyInfo pi in propertys)
                {
                    if (dt.Columns.Contains(pi.Name))
                    {
                        if (!pi.CanWrite) continue ;
                        object value = dr[pi.Name];
                        if (value != DBNull .Value)
                        {
                            pi.SetValue(model, value, null);
                        }
                        else
                        {
                            pi.SetValue(model, null, null );
                        }
                    }

                }
                list.Add(model);
            }

            return list;
        }


        public static DataTable ToDataTable< T>(IEnumerable <T> list)
        {
            List<PropertyInfo > pList = new List< PropertyInfo>();
            Type type = typeof (T);
            DataTable dt = new DataTable();
            Array.ForEach<PropertyInfo >(type.GetProperties(),
                p =>
                {
                    pList.Add(p);
                    Type colType = p.PropertyType;
                    if ((colType.IsGenericType) && (colType.GetGenericTypeDefinition() == typeof( Nullable<>)))
                    {
                        colType = colType.GetGenericArguments()[0];
                    }
                    dt.Columns.Add(p.Name, colType);
                });
            foreach (var item in list)
            {
                DataRow row = dt.NewRow();
                pList.ForEach(p => row[p.Name] = p.GetValue(item, null) == null ? DBNull.Value : p.GetValue(item, null));
                dt.Rows.Add(row);
            }
            return dt;
        }

       /// <summary>
        /// C#系統類型轉換為SQL數據庫類型
        /// </summary>
        /// <param name=" theType"></param>
        /// <returns></returns>
        public static SqlDbType GetDBType(System. Type theType)
        {
            System.Data.SqlClient. SqlParameter p1;
            System.ComponentModel. TypeConverter tc;
            p1 = new System.Data.SqlClient.SqlParameter ();
            tc = System.ComponentModel. TypeDescriptor.GetConverter(p1.DbType);
            if (tc.CanConvertFrom(theType))
            {
                p1.DbType = ( DbType)tc.ConvertFrom(theType.Name);
            }
            else
            {
                //Try brute force
                try
                {
                    p1.DbType = ( DbType)tc.ConvertFrom(theType.Name);
                }
                catch (Exception )
                {
                    //Do Nothing; will return NVarChar as default
                }
            }
            return p1.SqlDbType;
        }