DataTable转换成匿名类的List类型

 

因为匿名类是不能够 Activator.CreateInstance进行反射实例化的

/// <summary>
        /// 匿名类的转换方式
        /// </summary>
        /// <param name="GenericType"></param>
        /// <param name="dataTable"></param>
        /// <returns></returns>
        public static IList FromTable(Type GenericType, DataTable dataTable)
        {
            Type typeMaster = typeof(List<>);
            Type listType = typeMaster.MakeGenericType(GenericType);
            IList list = Activator.CreateInstance(listType) as IList;
            if (dataTable == null || dataTable.Rows.Count == 0)
                return list;
            var constructor = GenericType.GetConstructors(BindingFlags.Public | BindingFlags.NonPublic | BindingFlags.Instance)
                           .OrderBy(c => c.GetParameters().Length).First();
            var parameters = constructor.GetParameters();
            var values = new object[parameters.Length];
            foreach (DataRow dr in dataTable.Rows)
            {
                int index = 0;
                foreach (ParameterInfo item in parameters)
                {
                    object itemValue = null;
                    if (dr[item.Name] != null && dr[item.Name] != DBNull.Value)
                    {
                        itemValue = Convert.ChangeType(dr[item.Name], item.ParameterType.GetUnderlyingType());
                    }
                    values[index++] = itemValue;
                }
                list.Add(constructor.Invoke(values));
            }
            return list;
        }

        /// <summary>
        /// 匿名类的转换方式
        /// </summary>
        /// <typeparam name="T"></typeparam>
        /// <param name="dataTable"></param>
        /// <returns></returns>
        public static List<T> FromTable<T>(DataTable dataTable)
        {
            List<T> list = new List<T>();
            if (dataTable == null || dataTable.Rows.Count == 0)
                return list;
            //取当前匿名类的构造函数
            var constructor = typeof(T).GetConstructors(BindingFlags.Public | BindingFlags.NonPublic | BindingFlags.Instance)
                           .OrderBy(c => c.GetParameters().Length).First();
            //取当前构造函数的参数
            var parameters = constructor.GetParameters();
            var values = new object[parameters.Length];
            foreach (DataRow dr in dataTable.Rows)
            {
                int index = 0;
                foreach (ParameterInfo item in parameters)
                {
                    object itemValue = null;
                    if (dr[item.Name] != null)
                    {
                        itemValue = Convert.ChangeType(dr[item.Name], item.ParameterType.GetUnderlyingType());
                    }
                    values[index++] = itemValue;
                }
                T entity = (T)constructor.Invoke(values);
                list.Add(entity);
            }
            return list;
        }

使用方法

 var entity = new { Name = "item", ID = 0, GuidType = Guid.Empty };

            DataTable dataTable = new DataTable();
            dataTable.Columns.Add("Name", typeof(string));
            dataTable.Columns.Add("ID", typeof(int));
            dataTable.Columns.Add("GuidType", typeof(Guid));

            for (int i = 0; i < 10; i++)
            {
                DataRow dr = dataTable.NewRow();
                dr["Name"] = "STRING" + i;
                dr["ID"] = i;
                if (i % 2 == 0)
                    dr["GuidType"] = Guid.Empty;
                else
                {
                    dr["GuidType"] = DBNull.Value;
                }
                dataTable.Rows.Add(dr);
            }

            IList list = EntityExtensions.FromTable(entity.GetType(), dataTable);