合并表已经转化对象的操作

   写这个东西主要是当时 需要同时用到2个系统的数据，合并在一起操作，有点像SQL中的 left join 东西写得有点繁琐 ，当时准备用.net自己的 Merge（）方面但是好像不行不符合我的要求 无奈之下写下这些

       /// <summary>
        /// 2个DataTable合并DataTable
        /// </summary>
        /// <param name="FT"> DataTable</param>
        /// <param name="LT">DataTable</param>
        /// <param name="FtKeyName">关联的字段</param>
        /// <param name="LtKeyName">关联字段</param>
        /// <param name="AllColumnsName">要合并的字段</param>
        /// <returns></returns>
        public static DataTable MergeTable(DataTable FT, DataTable LT, string FtKeyName, string LtKeyName, params string[] AllColumnsName)
        {

            for (int i = 0; i < AllColumnsName.Length; i++)
            {
                FT.Columns.Add(AllColumnsName[i]);
            }
            foreach (DataRow row in FT.Rows)
            {
                for (int i = 0; i < LT.Rows.Count; i++)
                {
                    if (row[FtKeyName].ToString().Trim() == LT.Rows[i][LtKeyName].ToString().Trim())
                    {
                        for (int j = 0; j < AllColumnsName.Length; j++)
                        {
                            row[AllColumnsName[j]] = LT.Rows[i][AllColumnsName[j]];

                        }
                    }
                }

            }
            return FT;
        }
        /// <summary>
        /// 将实体转换成具有相同结构的DataTable 
        /// </summary>
        /// <typeparam name="T"></typeparam>
        /// <param name="model">要转换的实体</param>
        /// <returns></returns>
        public static DataTable ToDataTable<T>(List<T> model)
        {
            //检查实体集合不能为空
            if (model == null)
            {
                throw new Exception("需转换的集合为空");
            }
            //取出第一个实体的所有Propertie
            Type entityType = model.GetType();
            PropertyInfo[] entityProperties = entityType.GetProperties();


            DataTable dt = new DataTable();
            for (int i = 0; i < entityProperties.Length; i++)
            {
                dt.Columns.Add(entityProperties[i].Name, entityProperties[i].GetType());
            }
            foreach (object entity in model)
            {
                //检查所有的的实体都为同一类型
                if (entity.GetType() != entityType)
                {
                    throw new Exception("要转换的集合元素类型不一致");
                }
                object[] entityValues = new object[entityProperties.Length];
                for (int i = 0; i < entityProperties.Length; i++)
                {
                    entityValues[i] = entityProperties[i].GetValue(entity, null);

                }
                dt.Rows.Add(entity);
            }
            return dt;
        }
        /// <summary>
        /// 对象数组转换成DataTable 
        /// </summary>
        /// <param name="entities"></param>
        /// <returns></returns>
        public static DataTable FillToDataTable(object[] entities)
        {
            Type type = entities.GetType().GetElementType();
            PropertyInfo[] infoList = type.GetProperties();
            DataTable table = new DataTable();
            for (int i = 0; i < infoList.Length; i++)
            {
                PropertyInfo info = infoList[i];
                if (IsBaseType(info.GetType()))
                {
                    continue;
                }
                DataColumn column = new DataColumn();
                column.ColumnName = info.Name;
                column.DataType = info.PropertyType;
                table.Columns.Add(column);
            }
            for (int i = 0; i < entities.Length; i++)
            {
                object obj = entities[i];
                DataRow newRow = table.NewRow();
                for (int j = 0; j < infoList.Length; j++)
                {
                    PropertyInfo info = infoList[j];
                    if (IsBaseType(info.GetType()))
                    {
                        continue;
                    }
                    string name = info.Name;
                    object value = info.GetValue(obj, null);
                    if (value != null)
                    {
                        newRow[name] = value;
                    }
                }
                table.Rows.Add(newRow);
            }
            return table;
        }
        /// <summary>
        /// 验证是否同一类型 
        /// </summary>
        /// <param name="type">Type</param>
        /// <returns>根据返回验证结果</returns>
        private static bool IsBaseType(Type type)
        {
            return (type.IsValueType || type.IsPrimitive || type == typeof(string));
        }