I have a code-first, POCO project in which I am trying to adjust an existing database so that it syncs up with what EF is expecting, given my existing model.
I have these entities:
public class FlaggedDate
{
    [Key]
    public long scheduledDayID { get; set; }
    [Required]
    public DateTime date { get; set; }
    [StringLength(50)]
    [Required]
    public string dateStatus { get; set; }
    [Required]
    public bool isVisit { get; set; }
    [Required]
    public bool hasAvailableSlots { get; set; }
    [Required]
    public bool hasInterviewsScheduled { get; set; }
    // navigation properties
    public ICollection<ScheduledSchool> scheduledSchool { get; set; }
    public ICollection<Interview> interviews { get; set; }
    public ICollection<PartialDayAvailableBlock> partialDayAvailableBlocks { get; set; }
    public Visit visit { get; set; }
    public ICollection<Event> events { get; set; }
}
and
public class Visit
{
    [Key]
    public long flaggedDateScheduledDayID { get; set; }
    [Required]
    public bool isFullDay { get; set; }
    // navigation property
    public FlaggedDate flaggedDate { get; set; }
}
The relationship between these two is 1 : 0|1 -- i.e., FlaggedDate will exist but it may or may not have a corresponding single Visit object.
EF thinks, based on this model, that FlaggedDate should have an extra field, visit_flaggedDateScheduledDayID, which is nullable. I finally realized why: it thinks the Visit field, flaggedDateScheduledDayID, is an identity column. It's not supposed to be an identity column; it's supposed to be a foreign key that connects to FlaggedDate.
I think it does this by convention: I remember reading something to the effect that in CTP4, any field that is a single key and is int or long is assumed to be an identity column.
Is there any way I can tell EF that this is NOT an identity column? I tried fiddling with the Fluent API, but it's a mystery to me, and there are no data annotations that you can use for this.
Or, alternatively, is there any way I can fiddle with the navigation properties to get this to come out right?