Finding an element in a DbSet with a composite primary key

Question

I have the following model and am trying to find a specific object in a DbSet:

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

    [Key, Column(Order = 2)]
    [ForeignKey("Skill")]
    public int SkillId { get; set; }

    public virtual Skill Skill { get; set; }
}

I've tried the following two ways of finding a certain UserSkill object (I'm passing the DbSet of UserSkills via the ViewBag):

ViewBag.UserSkills.Find(new { WebSecurity.CurrentUserId, item.SkillId })
ViewBag.UserSkills.Find(new UserSkill(WebSecurity.CurrentUserId, item.SkillId))

But in both cases, I get an error:

The number of primary key values passed must match number of primary key values defined on the entity.

What am I missing? It seems to me that the primary key consists of two columns, and I'm providing the find function with the two values that comprise the primary key.

Answer 1

The signature of Find method is TEntity Find(params Object[] keyValues) and you can enlist the keys of composite primary key in proper order.

ViewBag.UserSkills.Find(WebSecurity.CurrentUserId, item.SkillId )

Answer 2

To find an entity by composite key you should use this overload

ViewBag.UserSkills.Find(WebSecurity.CurrentUserId, item.SkillId);

Msdn