实体框架级联删除（继承）

Question

I have read everything that I could find and still I couldn't solve my problem. I am using PostgreSQL and I have an abstract class and a child class. I would like that when the parent has been deleted also all related dependencies to be deleted.

Here is how my class looks like:

public abstract class NotificationModel
{
    [DatabaseGenerated(DatabaseGeneratedOption.Identity)]
    [Key]
    public Guid id { get; set; }
    public string type { get; set; }
    // and other common fileds
    public abstract NotificationModel buildObject(JObject json);
}

My child class:

class SmsNotificationModel : NotificationModel
{
    public override NotificationModel buildObject(JObject json){return dummyObj;}
    public SmsBody Body { get; set; }
    public Guid Fk_sms { get; set; }
}

And SmsBody

class SmsBody
{
    [DatabaseGenerated(DatabaseGeneratedOption.Identity)]
    [Key]
    public Guid Id { get; set; }
    public List<string> Recipients { get; set; }
    public string Route { get; set; }

    //edit
    public SmsNotificationModel smsNotModel { get; set; }
}

In DbContext:

 protected override void OnModelCreating(ModelBuilder modelBuilder)
 {
        modelBuilder.Entity<SmsNotificationModel>()
            .HasOne(em => em.Body)
            .WithOne(d => d.smsNotModel)
            .HasForeignKey<SmsNotificationModel>(f => f.Fk_sms)
            .OnDelete(DeleteBehavior.Cascade);

        base.OnModelCreating(modelBuilder);
  }

I don't understand what I am doing wrong. The table is marked as a cascade but when I try to drop this it does not work at all. Can somebody give me some tips about how can I set up this.

==== Later Edit

I have a generic repo for removing (template param is NotificationModel abstract class)

public class GenericRepository<T> : IGenericRepository<T> where T :class
{
    private readonly ApplicationDbContext _context;
    private DbSet<T> table = null;

    public GenericRepository(ApplicationDbContext _context) {
        this._context = _context;
        table = _context.Set<T>();
    }

    public void Delete(object id){
        T existing = table.Find(id);
        table.Remove(existing);
    }
}

Answer 1

One-to-One Relationship configuration applied to the post scenario.
Entities definition.

SmsNotification

public class SmsNotificationModel : NotificationModel
{
    public SmsBody Body { get; set; }
    // ...
}

SmsBody

public class SmsBody
{
    [DatabaseGenerated(DatabaseGeneratedOption.Identity)]
    [Key]
    public Guid Id { get; set; }
    // ...

    // I moved the Id relation here.
    // To me, it seems like Notification is the one-level-up absatraction model.
    // This may be changed at any time.
    public SmsNotificationModel SmsNotModel { get; set; }
    public Guid SmsNotificationModelId { get; set; }
}

Also, by the way, I made classes public . I am not sure if this is to important, by I believe that Entity Framework needs access from its own assembly to ours.

Then, configuring OnModelCreating .

public class YourContext : DbContext
{
    // ...

    public DbSet<SmsNotificationModel> Notifications { get; set; }
    public DbSet<SmsBody> SmsBodies { get; set; }

    protected override void OnModelCreating(ModelBuilder builder)
    {
        // ...

        builder.Entity<SmsNotificationModel>(entity =>
        {
            // Configures the One-To-One relationship
            // and the OnDelete behavior, as well.
            entity.HasOne<SmsBody>(notification => notification.Body)
                  .WithOne(body => body.SmsNotModel)
                  .HasForeignKey<SmsBody>(body => body.SmsNotificationModelId)
                  .OnDelete(DeleteBehavior.Cascade);
        });
    }
}

And, just for completion, the data-access layer.
I don't know if generic constrains fits with Entity Framework policies. I believe if does.
I just want to mention my way to go.

public interface IRepository<TEntity> : IDisposable
{
    // CRUD methods...

    void Delete(TEntity entity);
    void Delete(Expression<Func<TEntity, bool>> expression);

    void Save();
}

I like to have an interface defining all CRUD operations. Even an IAsyncRepository which defines the same operations, but async.

public class SmsRepository : IRepository<SmsNotificationModel>
{
    private readonly YourContext _context;

    public SmsRepository(YourContext context) =>  _context = context;

    // CRUD operations implementation ...

    public void Delete(SmsNotificationModel entity)
    {
        _context.Notifications.Remove(entity);
    }
}

You can continue reading an extended explanation if you face any truobles.

Hope it helps.