Create EF Foreign Key Through Fluent API

Question

Entity Framework isn't reacting to my data annotation changes in this particular scenario, so I want to try through Fluent API, which I never use.

I have a model "Transfer" which has three properties - its Id and "TransferredFromId" and "TransferredToId" properties, which represent Users (another EF model) involved in the transfer. Like so:

public class Transfer
{
    public long Id { get; set; }

    public long TransferredFromId { get; set; }
    [ForeignKey("TransferredFromId")]
    public User TransferredFrom { get; set; }

    public long TransferredToId { get; set; }
    [ForeignKey("TransferredToId")]
    public User TransferredTo { get; set; }
}

The user model currently looks like this:

public class User 
{
    public long Id { get; set; }

    [InverseProperty("TransferredFrom")]
    public ICollection<Transfer> TransferredFroms { get; set; }

    [InverseProperty("TransferredTo")]
    public ICollection<Transfer> TransferredTos { get; set; }
}

Note - I think user can look like this and it would still work:

public class User 
{
    public long Id { get; set; }
}

How do I achieve the exact same thing through Fluent API?

To clarify, I want to have a transfer table which has two properties, which both represent the Id from the Users table.

---

Temporary edit: Should my models look like this when I switch to Fluent API?

public class Transfer
{
    public long Id { get; set; }

    public long TransferredFromId { get; set; }

    public long TransferredToId { get; set; }
}

and

public class User 
{
    public long Id { get; set; }
}

and then add this in context?

        modelBuilder.Entity<Transfer>().HasRequired(x => x.TransferredFrom).WithMany(x => x.TransferredFroms).HasForeignKey(x => x.TransferredFromId);
        modelBuilder.Entity<Transfer>().HasRequired(x => x.TransferredTo).WithMany(x => x.TransferredTos).HasForeignKey(x => x.TransferredToId);

Answer 1

two possibilities, depending on which side you want to start on.

first, you have to override the OnModelCreating() method in your context.

your two options should look like:

modelBuilder.Entity<Transfer>().HasRequired(x=>x.TransferredFrom).WithMany(x=>x.TransferredFroms).HasForeignKey(x=>x.TransferredFromId);
modelBuilder.Entity<Transfer>().HasRequired(x=>x.TransferredTo).WithMany(x=>x.TransferredTos).HasForeignKey(x=>x.TransferredToId);

and

modelBuilder.Entity<User>().HasMany(x=>x.TransferredFroms).WithRequired(x=>x.TransferredFrom).HasForeignKey(x=>x.TransferredFromId);
modelBuilder.Entity<User>().HasMany(x=>x.TransferredTos).WithRequired(x=>x.TransferredTo).HasForeignKey(x=>x.TransferredToId);

each Set of these 2 lines should have the same semantics as your data annotation mapping.