c# - EF TPT 生成重复的外键

Question

我正在编写一个使用继承的应用程序，我试图将其映射到具有 TPT 结构的 SQL Server 数据库。

但是，出于某种原因，EF 在父类(super class)表和子类表中生成了重复的外键。

我有这些类(class):

public abstract class Answer
{
    public int AnswerId { get; set; }
    [Required]
    [MaxLength(250, ErrorMessage = "The answer cannot contain more than 250 characters")]
    public String Text { get; set; }
    [Required]
    [MaxLength(1500, ErrorMessage = "The description cannot contain more than 1500 characters")]
    public String Description { get; set; }

    public User User { get; set; }
}

public class AgendaAnswer : Answer
{
    [Required]
    public AgendaModule AgendaModule { get; set; }
}

public class SolutionAnswer : Answer
{
    [Required]
    public SolutionModule SolutionModule { get; set; }
}

public abstract class Module
{
    // for some reason EF doesn't recognize this as primary key
    public int ModuleId { get; set; }
    [Required]
    public String Question { get; set; }
    public String Description { get; set; }
    [Required]
    public DateTime StartTime { get; set; }
    [Required]
    public DateTime EndTime { get; set; }

    public virtual IList<Tag> Tags { get; set; }
}

public class AgendaModule : Module
{
    public IList<AgendaAnswer> AgendaAnswers { get; set; }
}

public class SolutionModule : Module
{
    public IList<SolutionAnswer> SolutionAnswers { get; set; }
}

public class User
{
    public int UserId { get; set; }
    public String FirstName { get; set; }
    public String LastName { get; set; }
    public int Zip { get; set; }
    public bool Active { get; set; }

    public virtual IList<AgendaAnswer> AgendaAnswers { get; set; }
    public virtual IList<SolutionAnswer> SolutionAnswers { get; set; }
}

这是我的 DbContext 类的内容:

public DbSet<AgendaModule> AgendaModules { get; set; }
public DbSet<SolutionModule> SolutionModules { get; set; }
public DbSet<AgendaAnswer> AgendaAnswers { get; set; }
public DbSet<SolutionAnswer> SolutionAnswers { get; set; }

protected override void OnModelCreating(DbModelBuilder modelBuilder)
{
    base.OnModelCreating(modelBuilder);

    modelBuilder.Conventions.Remove<OneToManyCascadeDeleteConvention>();

    modelBuilder.Entity<Module>().HasKey(m => m.ModuleId);
    modelBuilder.Entity<Answer>().HasKey(a => a.AnswerId);

    modelBuilder.Entity<AgendaAnswer>().Map(m =>
    {
        m.ToTable("AgendaAnswers");
    });

    modelBuilder.Entity<SolutionAnswer>().Map(m =>
    {
        m.ToTable("SolutionAnswers");
    });
}

当我运行我的应用程序时，EF 按照我想要的方式创建表 (TPT)，但它会为每个表中的用户复制外键(参见图片)。

提前致谢

Answer 1

如我在上面的评论中所述，解决方案是从 User 类中删除 AgendaAnswers 和 SolutionAnswers 属性。

如果您想将这些集合保留在 User 类中，您可能必须从 中删除 User 和 UserId 属性>Answer 类，而是在 AgendaAnswer 和 SolutionAnswer 类中复制它们。参见 this SO question获取更多信息。