EF与外键的多对多关系

Question

I want to configure many to many relationship between 2 entities but I would also like to expose their foreign keys. I found only one concrete solution online like following:

modelBuilder.Entity<E1>()
                            .HasMany(t => t.E1s)
                            .WithMany(t => t.E2s)
                            .Map(m =>
                            {
                                m.ToTable("E1E2");
                                m.MapLeftKey("FKE1");
                                m.MapRightKey("FKE2");
                            });

But map left and right key does not take a properties from my models so I do not have access to them and they will not be filled when I query. So, I do not have access to my foreign key properties.

Hope I was able to explain my problem. Can anyone suggest any other option?

Answer 1

You can create an associative model that has keys from the two entities:

public class AssociativeEntity
{
    [Key]
    public Guid AssociativeEntityId { get; set; }
    public Guid Entity1Id { get; set; }
    public Guid Entity2Id { get; set; }

    [Display(Name = "Entity1", ResourceType = typeof(Resources.Language))]
    public virtual Entity1 Entity1 { get; set; }
    [Display(Name = "Entity2", ResourceType = typeof(Resources.Language))]
    public virtual Entity2 Entity2 { get; set; }
}

Entity 1:

public class Entity1
{
    [Key]
    public Guid Entity1Id { get; set; }

    /* Describe the other properties here */

    [Display(Name = "AssociativeEntities", ResourceType = typeof(Resources.Language))]
    public virtual ICollection<AssociativeEntity> AssociativeEntities { get; set; }
}

Entity 2:

public class Entity2
{
    [Key]
    public Guid Entity2Id { get; set; }

    /* Describe the other properties here */

    [Display(Name = "AssociativeEntities", ResourceType = typeof(Resources.Language))]
    public virtual ICollection<AssociativeEntity> AssociativeEntities { get; set; }
}