How do I link two properties to one class but only being able to reference to one in EFC Code First?

Question

I have two Classes:

public class User
{
    public Guid UserId { get; set; }
    [Required]
    public string Username { get; set; }
    [Required]
    public string Password { get; set; }

    public UserProfile UserProfile { get; set; }
}

public class UserProfile
{
    public int UserProfileId { get; set; }
    public string Avatar { get; set; }

    public User User { get; set; }
    public User Wingman { get; set; }
}

Trying to add a migration understandably i get the following error:

Unable to determine the relationship represented by navigation property 'User.UserProfile' of type 'UserProfile'. Either manually configure the relationship, or ignore this property using the '[NotMapped]' attribute or by using 'EntityTypeBuilder.Ignore' in 'OnModelCreating'.

UserProfile.User is the user itself and UserProfile.Wingman is another user representig the wingman. Do i need another Table for that like a bridge or is there another way to resolve that problem? And I don't need to reference Wingman from the User .

Thanks in advance!

Answer 1

You can use the InversePropertyAttribute or the Fluent API config methods HasOne / WithOne or HasOne/WithMany with appropriate property selectors.

If you're looking for a 1:1 relationship, use a shard primary key - make the PK for UserProfile the FK to User.

modelBuilder.Entity<UserProfile>()
    .HasOne( up => up.User )
    .WithOne( u => u.UserProfile )
    .HasForeignKey( up => up.UserProfileId ); // I suggest renaming PK to UserId for clarity

If 1:N relationship, two ways; first, w/ InversePropertyAttribute :

public class User
{
    ...
    [InverseProperty( "User" )]
    public ICollection<UserProfile> UserProfiles { get; set; }
}

Or via Fluent API:

modelBuilder.Entity<UserProfile>()
    .HasOne( up => up.User )
    .WithMany( u => u.UserProfiles );