Post History

How to refer to the same table twice from one Entity Framework entity?

I have two classes, Contestant and Picture, with the following setup:

    public class Contestant 
    {
        ...
        public int AvatarID { get; set; }

        [ForeignKey(nameof(AvatarID))]
        public virtual Picture? Avatar { get; set; }
	
        public virtual ICollection<Picture>? Pictures { get; set; }
        ...
    }

    public class Picture
    {
        ...
        public int ContestantID { get; set; }
	
        [ForeignKey(nameof(ContestantID))]
        public virtual Contestant? Contestant { get; set; }
        ...
    }


Each contestant instance has a set of pictures and a single picture from the set that serves as their avatar.

The original setup (without AvatarID or Avatar relationship) worked fine. After adding the Avatar field and relationship, I get a run-time error message when I try to load either the Contestant set or Picture set. It reads:


 > System.InvalidOperationException: 'Unable to determine the relationship represented by navigation 'Contestant.Avatar' of type 'Picture.' Either manually configure the relationship, or ignore this property using the '[NotMapper]' attribute or by using 'EntityTypeBuilder.Ignore' in 'OnModelCreating'.' 

From my research, this happens when a class refers to another class twice. The answers I saw all involved the same class having both keys of the relationship. For example, a Project class might have multiple employees assigned, one as ProjectEngineer the other as AssignedDeveloper. For those, defining the [ForeignKey()] in the same file worked. I do not know what I need to do, here or possibly in the DbContext's OnModelCreating method.