使用 Entity Framework Core 在抽象基类中映射导航属性

Question

I have different Cars and each has a specific car type. All cars inherit from same abstract base class CarBase. The CarBase class has a navigaiton property to CarType.

public abstract CarTypeBase 
{ 
    public string Name { get; set; }
}

public class FordCarType : CarTypeBase 
{

}

public abstract class CarBase {
     public CarTypeBase CarType { get; set; }

     public string GetName() {
           return CarType.Name;
     }      
}

public class Ford : CarBase {

}

The Ford is mapped with the following EF mapping configuration:

builder.HasOne(o => (FordCarType) o.CarType);

For the CarTypeBase class I'm using the default Table per Hierarchy (TPH) mapping of Entity Framework, so the CarTypeBase table has a discriminator column. And the Ford table has a Foreign Key to CarTypeBase table.

The problem is that the Ford CarType navigation property is always null if I'm trying to access it for instance in the GetName() method. If I use instead the concrete type FordCarType the CarType property will be mapped in the Ford class.

So maybe what I want to achieve is not possible with EF or isn't possible at all?

Answer 1

Late to the party but, shouldn't this be:

public abstract CarTypeBase 
{ 
    public string Name { get; set; }
}

public abstract class CarBase : CarTypeBase  {
        
     public string GetName() {
           return this.Name;
     }      
}

public class Ford : CarBase {

}