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遞迴遞迴我愛你！只要你想做，就一定能成功！

從一到二，從二到三，它是容易的，也是沒什麼可搞的，或者說，它是一種流水線的方式，而從三到十，從十到百，它註定要有一個質的突破，否則，它會把你累死，程式碼寫的讓你自己都覺得想吐！有時，我們是被逼出來的，對於一種功能的實現，我們有時需要有從三到十的態度中，就像０的出現是人類最大的突破之一……

迴歸到例項，在MongoDB中實體可以巢狀，這在C#裡叫做複雜屬性，即類中也有類級的屬性，這在面向物件裡叫做“組合”(設計模式中的組合模式)，它經常在日常開發環境中見到，大家都耳熟能詳了，呵呵，而在mongodb裡，如果希望對N層巢狀的型別進行update操作，這絕對不是一件容易的事，最起碼在大叔框架裡，在面向linq的語法裡，它並不容易，但經過大叔的努力，和對遞迴的依賴，把這個問題解決了！

這才有今天的文章：遞迴遞迴我愛你！

一 從超級變態的類開始

 public class Person : Base
    {

        public Person()
        {
            Contact = new Test.Contact();
            OrderList = new List<Order>();
        }


        public string Name { get; set; }
        public DateTime LastContact { get
 
; set; }
        public DateTime Birthday { get; set; }
        public int Age { get; set; }

        #region 值物件
        /// <summary>
        /// 統計
        /// </summary>
        public Total Total { get; set; }
        /// <summary>
        /// 聯絡方式和地址
        /// </summary>
        public
 
 Contact Contact { get; set; }
        #endregion

        #region 列表實體
        public List<Order> OrderList { get; set; }
        #endregion
    }
    public class Section
    {
        public string SectionID { get; set; }
        public string SectionName { get; set; }
    }
    public class Area
    {
        public Area()
        {
            Section = new Section();
        }
        public string Province { get; set; }
        public string City { get; set; }
        public string District { get; set; }

        public Section Section { get; set; }
    }
    public class Contact
    {
        public Contact()
        {
            Area = new Area();
        }
        public string PostCode { get; set; }
        public string Email { get; set; }
        public string Phone { get; set; }

        public Area Area { get; set; }
    }
    public class Total
    {
        public int Count { get; set; }
        public int Max { get; set; }
    }
    public class Order
    {
        public Order()
        {
            Id = MongoDB.Bson.ObjectId.GenerateNewId().ToString();
            this.OrderDetail = new List<OrderDetail>();
            this.User_Info = new User_Info();
        }
        public string UserId { get; set; }
        public string UserName { get; set; }
        public string Id { get; set; }
        public double Price { get; set; }
        public DateTime AddTime { get; set; }

        public User_Info User_Info { get; set; }
        public List<OrderDetail> OrderDetail { get; set; }
    }

    public class User_Info
    {
        public User_Info()
        {
            Id = MongoDB.Bson.ObjectId.GenerateNewId().ToString();
        }
        public string Id { get; set; }
        public string Name { get; set; }
    }

    public class OrderDetail
    {
        public OrderDetail()
        {
            Id = MongoDB.Bson.ObjectId.GenerateNewId().ToString();
        }
        public string Id { get; set; }
        public string OrderId { get; set; }
        public string ProductName { get; set; }
        public int Count { get; set; }
        public double Price { get; set; }
        public string SellerId { get; set; }
    }

看到上面的類，絕對夠你喝一壺的，呵呵，這是一個複雜的型別People,它有實體屬性contact和列表屬性OrderList

而對於之前大叔的框架裡，這種結構是不被支援的，大叔只能支援到3級巢狀，但這顯然是不夠的，最後大叔硬著頭皮衝了上來，把這個骨頭啃掉了，哈哈！

下面貢獻我的Recursion程式碼

        /// <summary>
        /// 遞迴構建Update操作串
        /// </summary>
        /// <param name="fieldList"></param>
        /// <param name="property"></param>
        /// <param name="propertyValue"></param>
        /// <param name="item"></param>
        /// <param name="father"></param>
        private void GenerateRecursion(
              List<UpdateDefinition<TEntity>> fieldList,
              PropertyInfo property,
              object propertyValue,
              TEntity item,
              string father)
        {
            //複雜型別
            if (property.PropertyType.IsClass && property.PropertyType != typeof(string) && propertyValue != null)
            {
                //集合
                if (typeof(IList).IsAssignableFrom(propertyValue.GetType()))
                {
                    foreach (var sub in property.PropertyType.GetProperties(BindingFlags.Instance | BindingFlags.Public))
                    {
                        if (sub.PropertyType.IsClass && sub.PropertyType != typeof(string))
                        {
                            var arr = propertyValue as IList;
                            if (arr != null && arr.Count > 0)
                            {
                                for (int index = 0; index < arr.Count; index++)
                                {
                                    foreach (var subInner in sub.PropertyType.GetProperties(BindingFlags.Instance | BindingFlags.Public))
                                    {
                                        if (string.IsNullOrWhiteSpace(father))
                                            GenerateRecursion(fieldList, subInner, subInner.GetValue(arr[index]), item, property.Name + "." + index);
                                        else
                                            GenerateRecursion(fieldList, subInner, subInner.GetValue(arr[index]), item, father + "." + property.Name + "." + index);
                                    }
                                }
                            }
                        }
                    }
                }
                //實體
                else
                {
                    foreach (var sub in property.PropertyType.GetProperties(BindingFlags.Instance | BindingFlags.Public))
                    {

                        if (string.IsNullOrWhiteSpace(father))
                            GenerateRecursion(fieldList, sub, sub.GetValue(propertyValue), item, property.Name);
                        else
                            GenerateRecursion(fieldList, sub, sub.GetValue(propertyValue), item, father + "." + property.Name);
                    }
                }
            }
            //簡單型別
            else
            {
                if (property.Name != EntityKey)//更新集中不能有實體鍵_id
                {
                    if (string.IsNullOrWhiteSpace(father))
                        fieldList.Add(Builders<TEntity>.Update.Set(property.Name, propertyValue));
                    else
                        fieldList.Add(Builders<TEntity>.Update.Set(father + "." + property.Name, propertyValue));
                }
            }
        }

        /// <summary>
        /// 構建Mongo的更新表示式
        /// </summary>
        /// <param name="entity"></param>
        /// <returns></returns>
        private List<UpdateDefinition<TEntity>> GeneratorMongoUpdate(TEntity item)
        {
            var fieldList = new List<UpdateDefinition<TEntity>>();
            foreach (var property in typeof(TEntity).GetProperties(BindingFlags.Instance | BindingFlags.Public))
            {
                GenerateRecursion(fieldList, property, property.GetValue(item), item, string.Empty);
            }
            return fieldList;
        }

最後的結果，當然是在N層失敗之後，取得了成功，呵呵！

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