c# - Foreign Key mapping to composite keys in entity framework

Question

Trying to setup the following relationship with entity framework code first. The following code does not work I've tried many variations... does anyone have a clue?

CONSTRAINT [FK_EVENT_Contact] FOREIGN KEY (Patient_ID,[Contact_ID]) REFERENCES
[PatientContact](Patient_ID,Person_ID)



public class PatientContact
{
    [Key, Column(Order = 0)]
    [DatabaseGenerated(DatabaseGeneratedOption.None)]
    public int Person_ID { get; set; }
    public virtual Person Person { get; set; }

    [Key, Column(Order = 1)]
    [DatabaseGenerated(DatabaseGeneratedOption.None)]
    public int Patient_ID { get; set; }
    public virtual Patient Patient { get; set; }
}

public class Event
{
    [Key]
    public int Event_ID { get; set; }

    [Required]
    public int EventType_ID {get;set;}
    public virtual EventType EventType { get; set; }

    [ForeignKey("Patient")]
    public int Patient_ID { get; set; }
    public virtual Patient Patient { get; set; }

    [ForeignKey("PatientContact")]
    public int Contact_ID { get; set; }
    public virtual PatientContact PatientContact { get; set; }

}

Answer 1

You have 2 options here.

Use attributes as you have eg:

[ForeignKey("PatientContact"), Column(Order = 0)]
public int Person_ID{ get; set; }
[ForeignKey("PatientContact"), Column(Order = 1)]
public int Patient_ID{ get; set; }
public virtual PatientContact PatientContact { get; set; }

Use the model builder (fluent api)

modelBuilder.Entity<Event>()
    .HasRequired(p => p.PatientContact)
    .WithMany()
    .HasForeignKey(p => new {p.Person_ID, p.Patient_ID});