從兩個外鍵引用到兩個不同的表使複合鍵錯誤

Question

我有3個模型的用戶，ArticleComments和UserSubsription ..即時嘗試使3道具作爲組合鍵，其中兩個是外鍵引用兩個不同的表但我得到的錯誤嘗試啓用的遷移

User.CS

using System; 
using System.Collections.Generic; 
using System.ComponentModel.DataAnnotations; 
using System.ComponentModel.DataAnnotations.Schema; 
using System.Linq; 
using System.Web; 
using WebAppInternetApp.Models; 

namespace WebAppInternetApp.Models 
{ 
    public class User 
    { 

     public User() 
     { 
      this.WriterIDs = new HashSet<JobArticle>(); 
      this.AdminIDs = new HashSet<JobArticle>(); 
      this.UserIDs = new HashSet<ArticleComments>(); 
      this.UserIDss = new HashSet<UserQuestion>(); 
      this.UseerIDsss = new HashSet<UserSubscription>(); 
     } 

     [Key] 
     public int UID { get; set; } 

     [Required] 
     [StringLength(20, MinimumLength = 2)] 
     public string FName { set; get; } 

     [Required] 
     [StringLength(20, MinimumLength = 2)] 
     public string LName { set; get; } 

     [Required] 
     [DataType(DataType.EmailAddress)] 
     public string Email { set; get; } 

     [Required] 
     [StringLength(25, MinimumLength = 8)] 
     public string Password { set; get; } 

     [Required] 
     public bool Status { set; get; } 

     [Required] 
     [Phone] 
     public string PhoneNo { set; get; } 

     [Column(TypeName = "image")] 
     public byte[] UserImg { set; get; } 

     public virtual ICollection<JobArticle> WriterIDs { set; get; } 
     public virtual ICollection<JobArticle> AdminIDs { set; get; } 
     public virtual ICollection<ArticleComments> UserIDs { set; get; } 
     public virtual ICollection<UserQuestion> UserIDss { set; get; } 
     public virtual ICollection<UserSubscription> UseerIDsss { set; get; } 

     public virtual UserType usertypeIDs { set; get; } 



    } 
} 

文章Comments.CS

using System; 
using System.Collections.Generic; 
using System.Linq; 
using System.Web; 
using System.ComponentModel.DataAnnotations; 
using System.ComponentModel.DataAnnotations.Schema; 

namespace WebAppInternetApp.Models 
{ 
    public class ArticleComments 
    { 
     [Required] 
     public string Comment { set; get; } 
     [Key] 
     [Column(Order = 0)] 
     public DateTime CommentTime { set; get; } 
     [Key] 
     [Column(Order = 1)] 
     [ForeignKey("User")] 
     public virtual User UserID { set; get; } 
     [Key] 
     [Column(Order = 2)] 
     [ForeignKey("JobArticle")] 
     public virtual JobArticle ArticleID { set; get; } 
    } 
} 

UserSubsription.C小號

using System; 
using System.Collections.Generic; 
using System.ComponentModel.DataAnnotations; 
using System.ComponentModel.DataAnnotations.Schema; 
using System.Linq; 
using System.Web; 
using WebAppInternetApp.Models; 

namespace WebAppInternetApp.Models 
{ 
    public class UserSubscription 
    { 
     [Key] 
     [Column(Order = 0)] 
     [ForeignKey("User")] 
     public virtual User UserIDs { set; get; } 

     [Key] 
     [Column(Order = 1)] 
     [ForeignKey("JobCategory")] 
     public virtual JobCategory SubscriptID { set; get; } 
    } 
} 

Answer 1

基礎上微軟description of the ForeignKeyAttribute：

如果添加ForeigKey屬性外鍵屬性，您應該 指定關聯的導航屬性的名稱。如果 將ForeigKey屬性添加到導航屬性，您應該 指定關聯的外鍵的名稱。如果導航 酒店有多個外鍵，用逗號分隔的 外鍵的名稱

在你的代碼清單，你不定義外鍵屬性。您只定義導航屬性。

檢查這篇文章，看看如何使用ForeignKey的屬性：

Understanding ForeignKey attribute in entity framework code first

例如，您UserSubscription應該是這個樣子：

using System; 
using System.Collections.Generic; 
using System.ComponentModel.DataAnnotations; 
using System.ComponentModel.DataAnnotations.Schema; 
using System.Linq; 
using System.Web; 
using WebAppInternetApp.Models; 

namespace WebAppInternetApp.Models 
{ 
    public class UserSubscription 
    { 
     [Key] 
     [Column(Order = 0)] 
     [ForeignKey("User")] 
     public int UserIDs { set; get; } 

     [Key] 
     [Column(Order = 1)] 
     [ForeignKey("JobCategory")] 
     public int SubscriptID { set; get; } 

     // those are the navigation properties 
     public virtual User User { set; get; } 
     public virtual JobCategory JobCategory { set; get; } 
    } 
} 

而且ArticleComments可能是這樣的：

using System; 
using System.Collections.Generic; 
using System.Linq; 
using System.Web; 
using System.ComponentModel.DataAnnotations; 
using System.ComponentModel.DataAnnotations.Schema; 

namespace WebAppInternetApp.Models 
{ 
    public class ArticleComments 
    { 
     [Required] 
     public string Comment { set; get; } 

     [Key] 
     [Column(Order = 0)] 
     public DateTime CommentTime { set; get; } 

     [Key] 
     [Column(Order = 1)] 
     [ForeignKey("User")] 
     public int UserID { set; get; } 

     [Key] 
     [Column(Order = 2)] 
     [ForeignKey("JobArticle")] 
     public int ArticleID { set; get; } 

     public virtual User User { set; get; } 
     public virtual JobArticle JobArticle { set; get; } 

    } 
}