Question

I have a Quest and QuestTemplate class like below

public class Quest{

    public int ID {get;set;}

    public virtual QuestTemplate QuestTemplate {get;set;}

    public string Name{get;set;}
}

public class QuestTemplate{

    public int ID {get;set;}

    public QuestTemplate QuestTemplate {get;set;}

    public string Name{get;set;}

    public virtual Quest Quest{get;set;}
}

I create Quest and QuestTemplate like below in runtime

Quest q = new Quest();
q.Name = "Foo";
q.QuestTemplate = new QuestTemplate();
q.QuestTemplate.Name = "Bar";

context.Quests.Add(q);
context.SaveChanges();

It adds quest object and quest template object into related tables (Quests, QuestTemplates in this example). However the problem is that the Quest_ID column of quest template object in table is not set with quest object’s ID. Instead, it remains null. How can I resolve this problem?

P.S: I’m using EF5 with code first.

Best regards,

Kemal

Answer 1

Nowhere in the code did you specify the QuestTemplate applies to the Quest object. The following code should work:

Quest q = new Quest();
q.Name = "Foo";

QuestTemplate qt = new QuestTemplate();
qt.QuestTemplate.Name = "Bar";
qt.Quest = q;

q.QuestTemplate = qt;

context.Quests.Add(q);
context.SaveChanges();

Or you can map a one-to-one relationship.

modelBuilder.Entity<Quest >()
    .HasRequred(q => q.QuestTemplate)
    .WithRequiredPrincipal()
    .WillCascadeOnDelete();

Edit

Looked at this tonight and the reason for the relation isn’t mapping is in regards to the FK name. If you specify the FK in the fluent mapping, the relationship works as expected. Also, this type of 1-to-1 relationship requires either Quest or QuestTemplate be loaded first before the other (since it’s a required field) I randomly chose QuestTemplate below:

public class DataContext : DbContext
{
    public DbSet<Quest> Quests { get; set; }

    protected override void OnModelCreating(DbModelBuilder modelBuilder)
    {
        modelBuilder.Entity<Quest>()
            .HasOptional(q => q.QuestTemplate)
            .WithRequired(qt => qt.Quest)
            .Map(m => m.MapKey("QuestId"));
    }
}

public class Quest
{
    public int QuestId { get; set; }
    public string Name { get; set; }
    public virtual QuestTemplate QuestTemplate { get; set; }
}

public class QuestTemplate
{
    public int QuestTemplateId { get; set; }
    public string Name { get; set; }
    public virtual Quest Quest { get; set; }
}

class Program
{
    static void Main(string[] args)
    {
        using (DataContext db = new DataContext())
        {
            Quest q = new Quest { Name = "Bar" };
            q.QuestTemplate = new QuestTemplate { Name = "Foo" };
            db.Quests.Add(q);
            db.SaveChanges();
        }
    }
}

I believe it has something to do with the section titled Foreign Keys here, but I’m still not clear on why this is. I have other relationships configured exactly the same way without identifying the FK.