How to inherit @Entity not mapped class in Hibernate?

Question

Hibernate

The Field entity is required, which will be inherited by such classes as SliderField, DateField, etc., while they only perform the wrapper function and their data is already stored by Field in the form of an ArrayList
. It looks like this:

@Entity
class Field{

 public String val1;
// ...

public ArrayList<Data> data;

//...
}

class SliderField extends Field{
 public int min.max;

public void setMin(int m);
// ....
}

And in this case, Hibernate swears "Unknown entity: com.pkg.app.SliderField", although SliderField itself is not Mapped in any way, but is only transferred to .persist after explicit conversion to Field

Answer 1

If I understand correctly, all classes are projected onto one table. At the same time, Field contains projections of those fields of the table that are used in all classes, and Field's heirs project additional fields specific to them. In this case, the following construction should be suitable:

@MappedSuperclass
abstract class Field {
//...
}

@Entity
@Table(name = "FIELDS")
class SliderField extends Field {
//...
}

@Entity
@Table(name = "FIELDS")
class DateField extends Field {
//...
}

Your main mistake is that the @Entity annotation should mark final classes, not parent ones. Intermediate parent classes should be marked as @MappedSuperclass.