实体框架-父母不同的孩子

Question

I am using EF 6, Code First. I have a "contact" entity, a "customer" and a "manufacturer". Both customer and manufacturer have a list of contact entities. Maybe during development there can be more entities with a list of contact entities. How do I shape the contact entity so I do not have a separate Id as foreign key for customer and manufacturer? What I have in mind is something like:

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

    public int ParentId { get; set; }

    [ForeignKey("ParentId")]
    public virtual Customer Customer { get; set; }

    [ForeignKey("ParentId")]
    public virtual Manufacturer Manufacturer { get; set; }
}

Is this possible?

---

EDIT: Seems that it is not that easy. What I did was the following:

public class Customer 
{
    ...
    [InverseProperty("Customer")]
    public virtual ICollection<Contact> Contacts { get; set; }
    ....
}

public class Manufacturer
{
    ...
    [InverseProperty("Manufacturer")]
    public virtual ICollection<Contact> Contacts { get; set; }
    ...
}

public class Contact
{
    public int? ParentId { get; set; }

    [ForeignKey("ParentId")]
    public virtual Manufacturer Manufacturer { get; set; }

    [ForeignKey("ParentId")]
    public virtual Customer Customer { get; set; }
}

Now I have to include both manufacturer AND customer not manufacturer OR customer. Putting an "...HasOptional(...)" in ModelBuilder did not solve the problem.

????

Answer 1

You need to use the InverseProperty attribute on your customer and manufacturer fields, eg

[InverseProperty("Id")]
[ForeignKey("ParentId")]
public virtual Customer Customer { get; set; }

Read about it here.