Rails has-many-through equivalent in ASP.NET MVC3

Question

In .NET Entity Framework, what is the best way to have a (custom) join table with extra attributes (other than ids) and/or associate this join table with others via separate

Answer 1

Yes, you can get something pretty close. I'm not quite sure how to set this up in the designer since I only work with codefirst.

Here's an example:

Student -> StudentFloor <- Floor

public class Student
{
    public int Id { get; set; }
    // ... properties ...

    // Navigation property to your link table
    public virtual ICollection StudentFloors { get; set; }

    // If you wanted to have a property direct to the floors, just add this:
    public IEnumerable Floors
    {
        get
        {
            return StudentFloors.Select(ft => ft.Floor);
        }
    }
}

The linking table:

public class StudentFloor
{
    #region Composite Keys

    // Be sure to set the column order and key attributes.
    // Convention will link them to the navigation properties
    // below.  The database table will be created with a
    // compound key.

    [Key, Column(Order = 0)]
    public int StudentId { get; set; }

    [Key, Column(Order = 1)]
    public int FloorId { get; set; }

    #endregion

    // Here's the custom data stored in the link table

    [Required, StringLength(30)]
    public string Room { get; set; }

    [Required]
    public DateTime Checkin { get; set; }

    // Navigation properties to the outer tables
    [Required]
    public virtual Student Student { get; set; }

    [Required]
    public virtual Floor Floor { get; set; }

}

Finally, the other side of the many-to-many:

public class Floor
{
    public int Id { get; set; }
    // ... Other properties.

    public virtual ICollection StudentFloors { get; set; }
}