MVC 5 Code First Entity Framework Optional Relationship seperate PK from FK

Question

I want to configure a 'one to zero or one' relationship between ApplicationUser table and User table whereby ApplicationUser table is the principal and Student is the dependent. However, I would like to have a seperate Primary key for Student table and a Foreign Key that references ApplicationUser table's ApplicationUserID .

public class Student
{
    [Key]
    [Required]
    [StringLength(10)]
    public string StudentCode { get; set; }

    [Required]
    [StringLength(15)]
    [Column(TypeName = "varchar")]
    public string ContactNum { get; set; }

    public virtual ApplicationUser User { get; set; }

    [ForeignKey("User")]
    public string ApplicationUserID { get; set; }
}

public class ApplicationUser : IdentityUser
{
    public virtual Students Students { get; set; }
}

I've problem migrating this code as it raises an error of:

Student_User_Source: : Multiplicity is not valid in Role 'Student_User_Source' in relationship 'Student_User'. Because the Dependent Role properties are not the key properties, the upper bound of the multiplicity of the Dependent Role must be '*'.

So how do I configure this?

Answer 1

For one to one or zero relation do the folowing

Class ApplicationUser
{
[Key]
Int ApplicationUserId

// other properties
}

Class Student
{
[Key]
Int StudentId

Int? AppUserId

[ForeignKey("AppUserId")]
Virtual ApplicationUser AppUser
}

Now a Student can have one or Zero ApplicationUser

Plus you had the annotation of the foreign key reversed .. it is possible that this was the only problem