当类已经被引用为FK时EF多对多

Question

I am trying to create an Entity Framework many-to-many relationship between People and Penguins in the form of the usual PenguinPeople table holding Person_Id and Penguin_Id . When I generate a migration with the code below, the many-to-many is not created. However, if I comment out the 3 "OwnerId" lines in the Penguin class, the many-to-many works. What gives? They should be independent.

public class Penguin
{
    [DatabaseGenerated(DatabaseGeneratedOption.Identity)]
    public long Id { get; set; }

    public long OwnerId{ get; set; } //works if I comment this out
    [ForeignKey("OwnerId")] //works if I comment this out
    public Person Person{ get; set; } //works if I comment this out

    public virtual ICollection<Person> PenguinTrainers{ get; set; }
}

public class Person 
{
    [DatabaseGenerated(DatabaseGeneratedOption.Identity)]
    public long Id { get; set; }

    public virtual ICollection<Person> People{ get; set; }
}

Answer 1

If you have an

ICollection<Penguin> AssignedPenguins { get; set; }

on your Person class and just the Id properties on both classes then it should create the associative table.

Answer 2

I don't know if there is an easier way to do this, but I was forced to use FluentAPI as outlined in the EF docs . Example is just from docs, since obviously my penguin/person models were just made-up replacements for the ones actually causing the problem:

modelBuilder.Entity<Post>() 
                .HasMany(p => p.Tags) 
                .WithMany(t => t.Posts) 
                .Map(mc => 
                   { 
                       mc.ToTable("PostTags"); 
                       mc.MapLeftKey("Post_Id"); 
                       mc.MapRightKey("Tag_Id"); 
                   });