表中每个具体类型配置的抽象类

Question

I have this simple situation:

public abstract class Parent
{
    [Key]
    public Guid SomeId { get; set; }
}

public abstract class ParentArc
{
    public Guid ArcId { get; set; }

    public Guid StartNodeId { get; set; }
    public Guid EndNodeId { get; set; }

    public Parent StartNode { get; set; }
    public Parent EndNode { get; set; }
}

public class Node : Parent
{

}

public class Arc : ParentArc
{

}

And use these EntityTypeConfigurations:

public class ArcMapping : EntityTypeConfiguration<Arc>
{
    public ArcMapping()
    {
        HasKey(t => t.ArcId);
        HasRequired(p => p.StartNode).WithMany().HasForeignKey(p => p.StartNodeId).WillCascadeOnDelete(false);
        HasRequired(p => p.EndNode).WithMany().HasForeignKey(p => p.EndNodeId).WillCascadeOnDelete(false);
        Map(m =>
        {
        m.MapInheritedProperties();
        m.ToTable("Arc");
        });
    }
}

public class NodeMapping : EntityTypeConfiguration<Node>
{
    public NodeMapping()
    {
        HasKey(t => t.SomeId); 
        Map(m =>
        {
        m.MapInheritedProperties();
        m.ToTable("Node");
        });
    }
}

public class ParentArcMapping : EntityTypeConfiguration<ParentArc>
{
    public ParentArcMapping()
    {
        Map(m => m.ToTable("ParentArc"));
        HasRequired(p => p.StartNode).WithMany().HasForeignKey(p => p.StartNodeId).WillCascadeOnDelete(false);
        HasRequired(p => p.EndNode).WithMany().HasForeignKey(p => p.EndNodeId).WillCascadeOnDelete(false); 
    }
}

public class ParentMapping : EntityTypeConfiguration<Parent>
{
    public ParentMapping()
    {
        Map(m => m.ToTable("Parent"));
    }
}

In my DBContext I have:

public DbSet<Node> Nodes { get; set; }
public DbSet<Arc> Arcs { get; set; }

protected override void OnModelCreating(DbModelBuilder modelBuilder)
{
    modelBuilder.Conventions.Add<ForeignKeyNamingConvention>();

    modelBuilder.Configurations.Add(new ArcMapping());
    modelBuilder.Configurations.Add(new NodeMapping());
}

I have switched from Table per Type (TPT) to Table per Concrete Type (TPC) as this makes life easier during bulk import. The major downside is that TPC has no physical table for abstract classes and thus no foreign keys in the physical table dbo.Arc:

Is there anyway to change this?

Answer 1

You still need to add the mapping configuration for ParentArc and define the primary key and the relationships within there. The mapping for Arc does not need to define any relationships as it will inherit the base class's with the call to MapInheritedProperties()

public class ArcMapping : EntityTypeConfiguration<Arc>
{
    public ArcMapping()
    {
        Map(m =>
        {
            m.MapInheritedProperties();
            m.ToTable("Arc");
        });
    }
}

public class NodeMapping : EntityTypeConfiguration<Node>
{
    public NodeMapping()
    {
        HasKey(t => t.SomeId);
        Map(m =>
        {
            m.MapInheritedProperties();
            m.ToTable("Node");
        });
    }
}

public class ParentArcMapping : EntityTypeConfiguration<ParentArc>
{
    public ParentArcMapping()
    {
        HasKey(t => t.ArcId);
        HasRequired(p => p.StartNode).WithMany().HasForeignKey(p => p.StartNodeId).WillCascadeOnDelete(false);
        HasRequired(p => p.EndNode).WithMany().HasForeignKey(p => p.EndNodeId).WillCascadeOnDelete(false);
    }
}

and then in your OnModelCreating

protected override void OnModelCreating(DbModelBuilder modelBuilder)
{
    modelBuilder.Configurations.Add(new ParentArcMapping());

    modelBuilder.Configurations.Add(new ArcMapping());
    modelBuilder.Configurations.Add(new NodeMapping());

}