Question

This is my situation, very much simplified.

My classes;

public class ClassBase
{
    [Key]
    [DatabaseGenerated(DatabaseGeneratedOption.Identity)]
    public int Id { get; set; }
}

public class ClassMiddle1 : ClassBase
{

}

public class ClassMiddle2 : ClassBase
{
    public Guid Token { get; set; }
}

public class ClassA : ClassMiddle1
{
    public string UserId { get; set; }
    public string Username { get; set; }
}

public class ClassB : ClassMiddle2
{
    public string Username { get; set; }
}

And my OnModelCreating;

protected override void OnModelCreating(DbModelBuilder modelBuilder)
{
    modelBuilder.Entity<ClassBase>()
        .Map(m => {
            m.Properties(p => new { p.Id});
            m.ToTable("TableBase");
        });

    modelBuilder.Entity<ClassMiddle1>()
        .Map<ClassMiddle1>(m =>
        {
            m.Properties(p => new { });
            m.ToTable("TableBase");
        });

    modelBuilder.Entity<ClassMiddle2>()
        .Map<ClassMiddle2>(m =>
        {
            m.Properties(p => new { p.Token });
            m.ToTable("TableBase");
        });

    modelBuilder.Entity<ClassA>()
        .Map<ClassA>(m =>
        {
            m.Properties(p => new
            {
                p.UserId,
                p.Username
            });
            m.ToTable("TableA");

        });

    modelBuilder.Entity<ClassB>()
        .Map<ClassB>(m =>
        {
            m.Properties(p => new
            {
                p.Username
            });
            m.ToTable("TableB");

        }).Property(p => p.Username).HasColumnName("User");

}

This works fine but the Discriminator column is by default Discriminator, NVARCHAR(128). I read that it is possible to define this column myself using something like below.

m.Requires("ClassType").HasValue(1);

I turned my possibilities inside out but all times running into a dead end. Anyone having a suggestion how to do it?

I will end with another question. As our hierarchy pretty much are as above but even more derivated classes like C, D, E, F and so on to… say P. We found out that EF are making this incredibly big database query (~150K). Anyone else ran into this scenario?

I am hoping with changing Discriminator to at least minimize this. By that I say we have a very neat class hierarchy but an ugly query set.

Answer 1

Late answer how the actual solution went. Only writing it down here because the documentation around this was not that easy to find.

My solution ended up like below…

modelBuilder.Entity<ClassBase>()
        .Map(m => {
            ...
            m.Requires("Discriminator").HasValue(1)
        });