Question

I got the following codes:

public class Trip
{
    public int TripId { get; set; }

    public int DriverId { get; set; }

    public string StartingPoint { get; set; }

    public string Destination { get; set; }

    public DateTime TimeDepart { get; set; }

    public int SeatAvailable { get; set; }

    public virtual Carpooler Carpooler { get; set; }

    public virtual ICollection<Passenger> Passengers { get; set; }
}

public class Driver
{
    public int DriverId { get; set; }

    public int TripId { get; set; }

    public virtual Trip Trip { get; set; }
}

public class Passenger
{
    public int PassengerId { get; set; }

    public int TripId { get; set; }

    public virtual Trip Trip { get; set; }
}

A model builder:

    protected override void OnModelCreating(DbModelBuilder modelBuilder)
    {

        //one-to-one between Trip and Carpooler
        modelBuilder.Entity<Trip>()
            .HasRequired(x => x.Carpooler)
            .WithRequiredDependent();
        modelBuilder.Entity<Carpooler>()
            .HasRequired(x => x.Trip)
            .WithRequiredPrincipal();
        base.OnModelCreating(modelBuilder);

        //zero or one-to-many between Trip and Passenger
        modelBuilder.Entity<Trip>()
        .HasOptional(x => x.Passengers);

        modelBuilder.Conventions.Remove<IncludeMetadataConvention>();
    }

A initializer:

Database.SetInitializer<LiveGreenContext>(new CarpoolTripInitializer());

And i get the following error:
Multiplicity is not valid in Role ‘Trip_Driver_Target’ in relationship ‘Trip_Driver’. Because the Dependent Role properties are not the key properties, the upper bound of the multiplicity of the Dependent Role must be *.

Any solution for the problem? Thanks!

Answer 1

Configure the relationship between Trip and Driver. There is a DriverId property in Trip which is not configured. If you intend to use this as a navigational property you need to configure that too.

Some of the configuration were incomplete in your OnModelCreating method and are corrected.

protected override void OnModelCreating(DbModelBuilder modelBuilder)
{
    modelBuilder.Entity<Driver>()
        .HasRequired(x => x.Trip)
        .WithMany()
        .HasForeignKey(x => x.TripId);

    //one-to-one between Trip and Carpooler
    modelBuilder.Entity<Trip>()
        .HasRequired(x => x.Carpooler)
        .WithRequiredDependent();

    modelBuilder.Entity<Carpooler>()
        .HasRequired(x => x.Trip)
        .WithRequiredPrincipal();

    //zero or one-to-many between Trip and Passenger
    modelBuilder.Entity<Trip>()
    .HasMany(x => x.Passengers)
    .WithRequired(x => x.Trip)
    .HasForeignKey(x => x.TripId);

    base.OnModelCreating(modelBuilder);

    modelBuilder.Conventions.Remove<IncludeMetadataConvention>();
}