如何告诉EF核心两个型号使用同一个表？

Question

I'm migrating a classic SQL database to EF core 2.2 and I'm facing a problem. I'm not new to EF but I don't see how to do this...

Here is the problem, I have a table Users , a table Groups , and a table Members . Members are users composing Groups. I simplified models and kept only the keys :

public class User
{
    [Key]
    [DatabaseGenerated(DatabaseGeneratedOption.Identity)]
    public int Id { get; set; }

    public virtual ICollection<Group> Groups { get; set; }
}

public class Member
{
    [Key]
    public int UserId { get; set; }

    [ForeignKey(nameof(UserId))]
    public virtual User User { get; set; }

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

    [ForeignKey(nameof(GroupId))]
    public virtual Group Group { get; set; }
}

public class Group
{
    [Key]
    [DatabaseGenerated(DatabaseGeneratedOption.Identity)]
    public int Id { get; set; }

    public virtual ICollection<Member> Members { get; set; }
}

In classic SQL I can join tables by key, but how can I "jump" from Users to Groups like User.Groups ?

Answer 1

User already has a groups why do you need to include the group into Member? is not just having a user enough? If you need to read Members from DB then you can read them and use "Include" method to add User or Groups in your case. Something like this will do the job:

   var result = db.Members
                .Include(m => m.Groups)
                .Include(m => m.User)

Answer 2

Ok, I resolved this by another way :

User.Groups = context.Groups.Where(g => g.Members.Any(m => m.UserId == x.Id)).Select(g => new GenericData
{
    Id = g.Id,
    Tag = g.Tag,
    Label = g.Name,
    Flag = g.Flag
}).ToList()

Where x is the db user

It works like this, but if someone could say me how to do this like I wanted at start, I'm curious to know it :)