Question

We a mant-to-many relationship modeled in the database (with a bridge table) between Student and Professor, but in our entites we want to model it as a one-to-many relationship i.e. a Student has one Professor.

Here is our attempt, but it doesnt work:

protected StudentMap()
        {
            Id(x => x.Id);
            Map(x => x.Name);

            Join("student_professor_selected", m =>
            {                                                  
                m.KeyColumn("student_professor_selected_key");
                m.References(x => x.Professor);
             });
        }

Answer 1

Join is something completely different. It is used to put parts of a class into another table (one-to-one).

You just map a many-to-many relation from professor to student, it is always a simple List in C#.

It’s not possible to map it as a single ending reference from student to professor. But you could map a list of professors in a private property and implement a Professor property which just returns the first element:

private IList<Professor> professors;

public Professor Professor { get { return professors.First(); } }