EF代码优先：重复的外键（一个来自名称约定，一个来自导航属性） [英] EF Code First: Duplicate foreign keys (one from name convention, one from navigation property)

问题描述

我正尝试使用EF Code First创建一个SQL数据库。

I'm trying to create an SQL database by using EF Code First.

假设我有以下代码：

public class Account
{
    public int Id;
    public ICollection<User> Users;
}

public class User
{
    public int Id;
    public int AccountId;
}

public class AccountContext : DbContext
{
    public DbSet<Account> Accounts;
    public DbSet<User> Users;
}

（请注意，缺少任何Fluent API命令或数据注释；我想

(Note the lack of any Fluent API commands or Data Annotations; I want to do this by convention.)

创建数据库后，我在Users表中获得以下字段：

When the database is created, I get the following fields in the Users table:

Id
AccountId
Account_Id

为什么EF不能理解 AccountId是指Account的 Id主键这一事实？我希望避免在可能的情况下使用Fluent API / DA手动进行映射，并且希望避免在用户上拥有帐户导航属性。

Why isn't EF picking up on the fact that "AccountId" refers to the "Id" primary key (by convention) of Account? I want to avoid mapping this manually with Fluent API/DA if possible, and I want to avoid having the Account navigation property on User.

推荐答案

通过数据注释（非常快速）或流利的映射，我只有两种方法可以知道如何执行您要执行的操作。您不能只说 public int AccountId; 并期望一切正常。

There are only two ways i know how to perform what you are looking to do, either by Data Annotation (Very quick) or Fluent Mapping. You can't just say public int AccountId; and expect everything to work.

Fluent API映射双向

public class Account
{
   public int Id { get; set; }

   public ICollection<User> Users { get; set; }
}

public class User
{
   public int Id { get; set; }

   public Account Account { get; set; }
}

public class AccountContext : DbContext
{
   public AccountContext()
        : base("DefaultConnection")
    {

    }

   public DbSet<Account> Accounts { get; set; }
   public DbSet<User> Users { get; set; }

   protected override void OnModelCreating(DbModelBuilder modelBuilder)
    {
        modelBuilder.Entity<User>().HasRequired(u => u.Account) 
            .WithMany(a => a.Users) 
            .HasForeignKey(u => u.AccountId);
    }
}

双向数据注释

public class Account
{
   [Key]
   public int Id { get; set; }

   public ICollection<User> Users { get; set; }
}

public class User
{
   [Key]
   public int Id { get; set; }

   [ForeignKey("Account"), DatabaseGenerated(DatabaseGeneratedOption.None)]
   public int AccountId { get; set; }

   public Account Account { get; set; }
}

// and of course you need your context class, but with less code

public class AccountContext : DbContext
{
   public AccountContext()
        : base("DefaultConnection")
    {

    }

   public DbSet<Account> Accounts { get; set; }

   public DbSet<User> Users { get; set; }       
}

没有双向数据注释或Fluent API映射

public class Account
{
   public int Id { get; set; } //as Id in Accounts Table

   public ICollection<User> Users { get; set; }
}

public class User
{
   public int Id { get; set; } //as Id in Users Table

   public Account Account { get; set; } // as Account_Id in Users Table
}

// and of course you need your context class, but with less code

public class AccountContext : DbContext
{
   public AccountContext()
        : base("DefaultConnection")
    {

    }

   public DbSet<Account> Accounts { get; set; }

   public DbSet<User> Users { get; set; }       
}

我希望这可以帮助您或其他有疑问的人

I hope this helps you or anyone else in doubt

编辑

如果要避免使用双向导航，然后像这样更改个用户

If you want to avoid Bi-Directional navigation then make changes to Users like this

public class User
{
   public int Id { get; set; }

   //delete below from User class to avoid Bi-directional navigation 
   //public Account Account { get; set; }
}

注意：未经测试，但逻辑是声音

Note: Not tested but the logic is sound

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