Handling multiple Foreign Keys to the same database table in Entity Framework Code First

I recently encountered a requirement while working with Entity Framework Code First that required mapping more than 2 foreign keys to the same database table.

The convention for Entity Framework Code First, by default, does not make this easy simply by defining [ForeignKey] Data Annotations.

Fortunately, a quick search turned up this Stack Overflow thread: http://stackoverflow.com/questions/5559043/entity-framework-code-first-two-foreign-keys-from-same-table

This thread ultimately resulted in 2 possible solutions to this problem.

The first solution required the usage of the FluentAPI for Entity Framework Code First by relying on the OnModelCreating event in the DbContext class:

	public class Team
	{
	public int TeamId { get; set;}
	public string Name { get; set; }
	public virtual ICollection<Match> HomeMatches { get; set; }
	public virtual ICollection<Match> AwayMatches { get; set; }
	}
	public class Match
	{
	public int MatchId { get; set; }
	public int HomeTeamId { get; set; }
	public int GuestTeamId { get; set; }
	public float HomePoints { get; set; }
	public float GuestPoints { get; set; }
	public DateTime Date { get; set; }
	public virtual Team HomeTeam { get; set; }
	public virtual Team GuestTeam { get; set; }
	}
	public class Context : DbContext
	{
	protected override void OnModelCreating(DbModelBuilder modelBuilder)
	{
	modelBuilder.Entity<Match>()
	.HasRequired(m => m.HomeTeam)
	.WithMany(t => t.HomeMatches)
	.HasForeignKey(m => m.HomeTeamId)
	.WillCascadeOnDelete(false);
	modelBuilder.Entity<Match>()
	.HasRequired(m => m.GuestTeam)
	.WithMany(t => t.AwayMatches)
	.HasForeignKey(m => m.GuestTeamId)
	.WillCascadeOnDelete(false);
	}
	}

view raw EFCodeFirstMultipleFKs.cs hosted with ❤ by GitHub

The second solution required the use of the [InverseProperty] Data Annotation instead:

	public class Team
	{
	public int TeamId { get; set;}
	public string Name { get; set; }
	[InverseProperty("HomeTeam")]
	public virtual ICollection<Match> HomeMatches { get; set; }
	[InverseProperty("GuestTeam")]
	public virtual ICollection<Match> AwayMatches { get; set; }
	}
	public class Match
	{
	public int MatchId { get; set; }
	public float HomePoints { get; set; }
	public float GuestPoints { get; set; }
	public DateTime Date { get; set; }
	public virtual Team HomeTeam { get; set; }
	public virtual Team GuestTeam { get; set; }
	}

view raw EFCodeFirstMultipleFKsDataAnnotations.cs hosted with ❤ by GitHub