如何映射實體框架的關係

Question

我有3個表

================= ================= ================= 
| TableA  | | RelationAC | | TableC  | 
================= ================= ================= 
| IdA   | | Id   | | IdC   | 
|    | | IdA   | |    | 
| Field1A  | | IdC   | | Field1C  | 
================= ================= ================= 

這是我的模型代碼：

public partial class TableA 
{ 
    public TableA() 
    { 
     this.RelationAC = new HashSet<RelationAC>(); 
    } 

    [Key] 
    public decimal IdA { get; set; } 
    public string Field1A { get; set; } 
    [ForeignKey("IdA")] 
    public virtual ICollection<RelationAC> RelationAC { get; set; } 
} 

public partial class TableC 
{ 
    [Key] 
    public decimal IdC { get; set; } 
    public string Field1C { get; set; } 
} 


public partial class RelationAC  
{ 
    public RelationAC () 
    { 
     this.TableC= new HashSet<TableC>(); 
    } 
    [Key] 
    public decimal Id { get; set; } 
    public decimal IdA{ get; set; } 
    public decimal IdC{ get; set; } 

    [ForeignKey("IdC")] 
    public virtual ICollection<TableC> TableC { get; set; } 
} 

如果使這個查詢

var query = from d in db.TableA 
      select d; 


foreach(TableA ta in query.Tolist()) 
{ 
    foreach(RelationAC rac in ta.RelationAC.Tolist()) 
    { 
     TableC tc = rac.TableC.First(); // It allways has count = 0 , even my db has data 
    } 
} 

爲什麼表C TC總是空的？

Answer 1

您的財產可能是有問題/延遲加載。嘗試熱切加載收藏：

db.TableA.Include("RelationAC.TableC")