How to make a mapped field inherited from a superclass transient in JPA?
- by Russ Hayward
I have a legacy schema that cannot be changed. I am using a base class for the common features and it contains an embedded object. There is a field that is normally mapped in the embedded object that needs to be in the persistence id for only one (of many) subclasses. I have made a new id class that includes it but then I get the error that the field is mapped twice. Here is some example code that is much simplified to maintain the sanity of the reader:
@MappedSuperclass
class BaseClass {
@Embedded
private Data data;
}
@Entity
class SubClass extends BaseClass {
@EmbeddedId
private SubClassId id;
}
@Embeddable
class Data {
private int location;
private String name;
}
@Embeddable
class SubClassId {
private int thingy;
private int location;
}
I have tried @AttributeOverride but I can only get it to rename the field. I have tried to set it to updatable = false, insertable = false but this did not seem to work when used in the @AttributeOverride annotation. See answer below for the solution to this issue.
I realise I could change the base class but I really do not want to split up the embedded object to separate the shared field as it would make the surrounding code more complex and require some ugly wrapping code. I could also redesign the whole system for this corner case but I would really rather not.
I am using Hibernate as my JPA provider.
