declare TPH with existing TPT (Code First)

Question

I have couple of classes which inherits 1 base abstract class. It is mapped via fluent API to existing database (using Table-Per-Concrete-Type, i.e. base abstract class not mapped to any table).

Now I want to add some statistics to my code and the best solution for me is to use TPH approach for 3-4 new classes. It maybe or maybe not inherits the same class as described above.

But I do not know how to instruct EF use TPH-approach for these 3-4 classes. Am I need to add correect table with discriminators and it will be used ok? Or I need to specify it somehow via fluent API?

Answer 1

I found. You do not need to specify somehow EF that you want to use TPH. Enough to do following:

Create classes hierarchy

class Base { ... }
class Derived1 : Base { ... }
class Derived2 : Base { ... }
.......
class DerivedN : Base { ... }

Create table called as your base type (otherwise do not forget to map it using ModelBuilder) with common columns (content of Base) and with one column per public property in each derived types. Add "Discriminator" column (nvarchar(128), but I suggest to use varchar unless you using unicode classes names).

In your successor of DbContext add only one DbSet: DbSet<Base> Data { get; set; } and use it for CRUD operations.

That is all!