How do I specify a one to one relationship in Entity Framework Core where both sides have a foreign-CodePudding

All the documentation I'm finding on one to one relationships in Entity Framework talk about one side being the dependent and only having a foreign key in one table. How can I tell Entity Framework that both tables have a foreign key to each other. Here is a simple example:

public class TechnicalAdvisor
{
  public Guid TechnicalAdvisorId { get; set; }
  public Guid ProjectRequestId { get; set; }
  public virtual ProjectRequest ProjectRequest { get; set; }
}

public class ProjectRequest 
{
  public Guid ProjectRequestId { get; set; }
  public Guid? TechnicalReviewCompletedById { get; set; }
  public virtual TechnicalAdvisor TechnicalReviewCompletedBy { get; set; }
}

The use case is we have a project request that requires technical review. The TechnicalAdvisor table is a whitelist basically for who can do it. Then we need an id for who actually did it. I can't figure out how to tell Entity Framework what this relationship is.

CodePudding user response：

You're almost there. You just need an additional table to represent the TechincalAdvisors who are on the Whitelist.

public class TechnicalAdvisorWhitelist
{
  public int Id {get; set;} 
  public Guid TechnicalAdvisorId  {get; set;}
}

CodePudding user response：

So I was seeing this wrong. Really I had two relationships: 1:0/1 and 1:many so really the answer is this:

modelBuilder.Entity<TechnicalAdvisor>()
            .HasOne(x => x.ProjectRequest)
            .WithMany()
            .HasForeignKey("ProjectRequestId");

modelBuilder.Entity<ProjectRequest>()
            .HasOne(x => x.TechnicalReviewCompletedBy)
            .WithOne()
            .HasForeignKey<ProjectRequest>(x => x.TechnicalReviewCompletedById);