生成序列號。在列表中使用LINQ

Question

我有三個模型和一個View模型。該模型是這樣的：

public partial class SalesDetail 
    { 
     public long IID { get; set; } 
     public Nullable<long> SalesId { get; set; } 
     public int ItemId { get; set; } 
     public int UoM { get; set; } 
     public int Qty { get; set; } 
     public Nullable<decimal> Disc { get; set; } 

     public virtual General General { get; set; } 
     public virtual Item Item { get; set; } 
     public virtual Sale Sale { get; set; } 
    } 

public partial class Item 
    { 
       public Item() 
     { 
      this.SalesDetails = new HashSet<SalesDetail>(); 
     } 

     public int IID { get; set; } 
     public string Item1 { get; set; } 
     public int UoM { get; set; } 

     [System.Diagnostics.CodeAnalysis.SuppressMessage("Microsoft.Usage", "CA2227:CollectionPropertiesShouldBeReadOnly")] 
     public virtual ICollection<SalesDetail> SalesDetails { get; set; } 
    } 



    public partial class General 
     { 
      public General() 
      { 
       this.Parties = new HashSet<Party>(); 
       this.Parties1 = new HashSet<Party>(); 
       this.SalesDetails = new HashSet<SalesDetail>(); 
      } 

      public int IID { get; set; } 
      public string Value { get; set; } 
      public string Desciption { get; set; } 
      public byte Type { get; set; } 
      public Nullable<int> ParentID { get; set; } 
} 

我也有一個像視圖模型：

public class SalelsDetailListViewModel 
    { 
     public int SerialNo { get; set; } 
     public Int64 Id { get; set; } 
     public int ItemId { get; set; } 

     public string ItemName { get; set; } 

     public int UoM { get; set; } 

     public string UnitName { get; set; } 

     public int Qty { get; set; } 

     public decimal? Disc { get; set; } 
    } 

我試圖生成序列號。同時執行linq查詢作爲列表。稍後，此列表將顯示爲序列號爲的表格。 我寫了下面的查詢。

lstDetails = (from d in db.SalesDetails 
            join i in db.Items on d.ItemId equals i.IID 
            join u in db.Generals on d.UoM equals u.IID 
            select new SalelsDetailListViewModel 
                     { 
             SerialNo = ???, 
             Id = d.IID, 
             ItemId = i.IID, 
             ItemName = i.Item1, 
             UoM = u.IID, 
             UnitName = u.Value, 
             Qty = d.Qty, 
             Disc = d.Disc 
            }).ToList(); 

我不明白如何增加與其他項目的查詢內序列號。 任何幫助將被感謝接受。

感謝

帕塔

Answer 1

爲什麼不能簡單地遍歷結果和使用計數器設置？
你有幾個元素？你關心性能嗎？

你面臨什麼困難？

var counter = 0; 
foreach (var x in lstDetails) x.SerialNo = counter++; 

你也可以做它在原來的查詢，如下圖所示（使用C＃7 ValueTuple）

var sample = new [] { "a", "b", "c" }; 
var count = 0; 
sample.Select(x => (x, count++)).ToList(); 
// result 
// List<ValueTuple<string, int>>(3) { [(a, 1)], [(b, 2)], [(c, 3)] } 

或匿名類型，try with Fiddle

var sample = new [] { "a", "b", "c" }; 
var count = 0; 
sample.Select(x => new { x, c = count++ }).ToList(); 
// result 
// List<<>f__AnonymousType0#8<string, int>>(3) { \{ x = "a", c = 1 }, \{ x = "b", c = 2 }, \{ x = "c", c = 3 } } 

Answer 2

編輯：這是一種更好的替代解決方案

var lstDetails = (from d in salesDetailsList 
         join i in itemList on d.ItemId equals i.IID 
         join u in generalList on d.UoM equals u.IID 
         select new 
         { 
          Id = d.IID, 
          ItemId = i.IID, 
          ItemName = i.Item1, 
          UoM = u.IID, 
          UnitName = u.Value, 
          Qty = d.Qty, 
          Disc = d.Disc 
         }) 
         .Select((s, index) => new SalesDetailListViewModel() 
         { 
          SerialNo = index, 
          Id = s.Id, 
          ItemId = s.ItemId, 
          ItemName = s.ItemName, 
          UoM = s.UoM, 
          UnitName = s.UnitName, 
          Qty = s.Qty, 
          Disc = s.Disc 
         }).ToList();