Foreign key mapping for composite keys in entity structure

Question

First, try to establish the following relationships with the entity. The following code does not work. I tried many options ... who has 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.

Use attributes as you have, for example:

 [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 model builder (free api)

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