Ndtyjky

I'm creating an MVC application using Entity Framework, and I'm using Code First conventions. There's a particular relationship which I'm unsure about.

I added staff roles to break up the many to many relationship between staff and modules. A module should always have a module leader and a number of tutors. Currently my entities look like this:

public class Staff

{

    public int StaffId { get; set; }



    [Required]

    public string FirstName { get; set; }



    [Required]

    public string LastName { get; set; }



    public string EmailAddress { get; set; }



    public int? PhoneNumber { get; set; }



    public string Full

    {

        get

        {

            return LastName + ", " + FirstName;

        }

    }



    public virtual List<StaffRole> Roles { get; set; }



}



   public enum StaffModuleRoles

{

    Leader,

    Tutor

}





public class StaffRole

{

    [Key, ForeignKey("Staff"), Column(Order = 0)]

    public int StaffId { get; set; }



    [Key, ForeignKey("Module"), Column(Order = 1)]

    public string ModuleCode { get; set; }



    public StaffModuleRoles Role { get; set; }



    public Staff Staff { get; set; }



    public Module Module { get; set; }

}



 public class Module

{



    [Key]

    public string ModuleCode { get; set; }



    [MaxLength(50)]

    [Required]

    public string Title { get; set; }



    public string Description { get; set; }



    public List<Enrolment> Enrolments { get; set; }



    public Staff ModuleLeader { get; set; }



    public virtual List<Staff> Tutors { get; set; }



}

What's the best practice here? As you can see, I mostly use data annotations and I'm fairly new to EF and coding in general.

Any help would be appreciated, additional thanks for tips on seeding the entities as well.

Edit in response to comments

I'm interested to know if my database design is correct and if so, how do I create this using Entity Framework.

As for your design, you may want to rethink the structure of these tables. Here is why I say that. By giving your module entity the ModuleLeader property, you are effectively saying "A module can only have 1 staff member", but then you put a M:M relationship in the mix with StaffModule which says "A module can have many staff members". I understand why you did this, but it really isn't the right thing to do. In your domain, the notion of a leader is a characteristic of the relationship, not a characteristic of the module.

Couple of options to consider: 1) Add another field to StaffModule like "IsLeader". This way your M:M relationship is responsible for owning which of the relationships is the leader and which are the tutors. 2) Consider changing your StaffModule table to Tutors and do not put the leader in this table at all. Model that relationship by doing what you have already....a ModuleLeader on your module that points directly to staff. The tutors table would only be the staff that are tutors. Both of these have pros/cons that you need to weigh to decide what is best.