Map entities to many-to-many junction table in EF 4.5

Question

At the moment I’m mapping my existing DB tables to new EF 4.5 model via Fluent Api. I’ve got a questing on how to map following db structure to classes.

Students(pk Id...)
Courses (pk Id...)
Students_Courses (pk Id, fk StudentId, fk CourseId)
Comments (pk Id, fk Students_Courses Id, comment, dateposted...)

The idea is that I may have many reviews per student_course pair. What is the best way to represent my classes in this scenario? The problem here is that I’ll probably need to map Comment entity to Students_Courses table and somehow determine to which Student and Course (in terms of classes) this comment belongs. Any suggestions on the design? Thanks!

Answer 1

Maybe you'd like to use Entity Framework Power Tools to reverse-engineer your data model into a "code -first" model with DbContext API.

You will see that something like a StudentCourse class will be generated that looks like this:

public class StudentCourse
{
    public StudentCourse()
    {
        this.Comments = new List<Comment>();
    }

    public int StudentCourseId { get; set; }
    public int StudentId { get; set; }
    public int CourseId { get; set; }
    public virtual ICollection<Comment> Comments { get; set; }
    public virtual Course Course { get; set; }
    public virtual Student Student { get; set; }
}

and Comment looking like this:

public class Comment
{
    public int CommentId { get; set; }
    public int StudentCourseId { get; set; }
    public virtual StudentCourse StudentCourse { get; set; }
    ...
}

So comments are related with students and courses through StudentCourse