實體框架 - 代碼優先 - 數據註釋 - 不必要的外鍵列

Question

實體框架在我的AccountCompanyRole表中創建兩個不必要的列。

AccountCompany

public class AccountCompany 
{ 
    [Key, Column(Order = 0), ForeignKey("Account")] 
    public int AccountID { get; set; } 

    [Key, Column(Order = 1), ForeignKey("Company")] 
    public int CompanyID { get; set; } 

    public virtual Account Account { get; set; } 

    public virtual Company Company { get; set; } 

    public virtual ICollection<AccountCompanyRole> AccountCompanyRoles { get; set; } 
} 

AccountCompanyRoles

public class AccountCompanyRole 
{ 
    [Key, Column(Order = 0), ForeignKey("AccountCompany")] 
    public int AccountID { get; set; } 

    [Key, Column(Order = 1), ForeignKey("AccountCompany")] 
    public int CompanyID { get; set; } 

    [Key, Column(Order = 2), ForeignKey("Role")] 
    public int RoleID { get; set; } 

    public virtual AccountCompany AccountCompany { get; set; } 

    public virtual Role Role { get; set; } 
} 

OnModelCreating

protected override void OnModelCreating(DbModelBuilder modelBuilder) 
    { 
     modelBuilder.Entity<AccountCompanyRole>() 
      .HasRequired(p => p.AccountCompany) 
      .WithMany() 
      .WillCascadeOnDelete(false); 

     base.OnModelCreating(modelBuilder); 
    } 

結果在DB

正如你所看到的，EF甚至壽我指定的主密鑰和數據註釋外鍵增加了兩個外鍵在AccountCompanyRoles。

問題

1. 如何防止它從創建AccountCompany_AccountID和AccountCompany_CompanyID？

2. 這是我以後的最佳結構嗎？我是否應該使用一個主鍵並將IsUnique索引放在AccountID和CompanyID上？這可能會解決我的問題..

Answer 1

您的這樣流暢關係到指定的外鍵：

modelBuilder.Entity<AccountCompanyRole>() 
      .HasRequired(p => p.AccountCompany) 
      .WithMany().HasForeignKey(d => new { d.AccountID, d.CompanyID }) 
      .WillCascadeOnDelete(false); 

     modelBuilder.Entity<AccountCompany>() 
      .HasMany(c => c.AccountCompanyRoles) 
      .WithRequired(d => d.AccountCompany) 
      .HasForeignKey(e => new {e.AccountID, e.CompanyID}); 

編輯： 增加了AccountCompany

Answer 2

如何防止它從創建AccountCompany_AccountID和AccountCompany_CompanyID？

首先，從CompanyID和RoleID除去ForeignKey屬性。

然後要麼把ForeignKey屬性您AccountCompany成員像這樣的：

public class AccountCompanyRole 
{ 
    [Key, Column(Order = 0)] 
    public int AccountID { get; set; } 

    [Key, Column(Order = 1)] 
    public int CompanyID { get; set; } 

    [Key, Column(Order = 2), ForeignKey("Role")] 
    public int RoleID { get; set; } 

    [ForeignKey("AccountID, CompanyID")] 
    public virtual AccountCompany AccountCompany { get; set; } 

    public virtual Role Role { get; set; } 
} 

或用流利的配置是這樣的：

modelBuilder.Entity<AccountCompanyRole>() 
      .HasRequired(r => r.AccountCompany) 
      .WithMany(c => c.AccountCompanyRoles) 
      .HasForeignKey(r => new { r.AccountID, r.CompanyID }) 
      .WillCascadeOnDelete(false); 

這是爲了什麼，我之後的最佳結構？我是否應該使用一個主鍵並將IsUnique索引放在AccountID和CompanyID上？這可能會解決我的問題..

IMO都是有效的方法，使用更適合您的需求。