Migrating from @GenericGenerator to @IdGeneratorType

Hibernate ORM
1

Hi, we are upgrading our spring boot version from 3.2.5 to 3.4.X which also comes with a hibernate upgrade to 6.6. As it has been mentioned in other posts, this has broken some legacy tests in which an explicit id was set for entity classes for which the id was supposed to be auto-generated. Re-writing these tests is not an option for us mainly because of the number of these, as well as the fact, that this is a monolith repository with lots of legacy code/tests.

We tried following the approach suggested in other posts and using a custom class extending SequenceStyleGenerator like so:

public class SequenceOrAssignedGenerator extends SequenceStyleGenerator {
  @Override
  public Object generate(SharedSessionContractImplementor session, Object object) throws HibernateException {
    Object id = session.getEntityPersister(null, object).getIdentifier(object, session);
    return id == null ? super.generate(session, object) : id;
  }

  @Override
  public boolean allowAssignedIdentifiers() {
    return true;
  }
}

and then used @GenericGenerator in our entity classes like so:

@Entity
@Table(name="sgroup")
public class SomeClass {
  @Id
  @GenericGenerator(
      name = "group_id_seq",
      strategy = "com.test.SequenceOrAssignedGenerator",
      parameters = {
          @Parameter(name = SequenceStyleGenerator.SEQUENCE_PARAM, value = "group_id_seq"),
          @Parameter(name = SequenceStyleGenerator.INITIAL_PARAM, value = "1"),
          @Parameter(name = SequenceStyleGenerator.INCREMENT_PARAM, value = "1")
      }
  )
  @GeneratedValue(strategy = GenerationType.SEQUENCE, generator = "group_id_seq")
  @Column(name = "id", updatable=false)
  public Long id;
}

This seems to work and does solve our problem. However, we observed that @GenericGenerator has been marked deprecated since 6.5 and we ideally would like a more future-proof solution.

Digging a bit further we found that @IdGeneratorType is now what’s being used for this purpose. So as described in the examples we created a custom annotation like so:

@IdGeneratorType(SequenceOrAssignedGenerator.class)
@Retention(RetentionPolicy.RUNTIME)
@Target({FIELD})
public @interface CustomGen {
  String sequenceName();
  int initialValue() default 1;
  int incrementSize() default 1;
}

and went back to annotate our id field like so:

@Entity
@Table(name="sgroup")
public class SomeClass {
  @Id
  @CustomGen(sequenceName = "group_id_seq", initialValue = 1, incrementSize = 1)
  @GeneratedValue(strategy = GenerationType.SEQUENCE, generator = "group_id_seq")
  @Column(name = "id", updatable=false)
  public Long id;
}

However, with this although we don’t get the ObjectOptimisticLocking FailureException that we used to get before introducing @GenericGenerator, we do now get a SchemaManagementException: Schema-validation: missing sequence [sgroup_seq], which indicates that the sequence has not been created. (But the sequence should have been called group_id_seq instead?)

Are we missing some additional @IdGeneratorType config here? Any pointers?

2

Like I wrote in OptimisticLockException when manually setting the ID for the entity, you should be able to mark the SequenceOrAssignedGenerator as bean e.g. with @Component and then you wouldn’t have to change anything in the mappings. If you want to go the route of @IdGeneratorType I think you simply have to remove the @GeneratedValue.

3

Thanks for the reply @beikov. However, neither of the two suggestions seem to work for us.

The former (marking @SequenceOrAssignedGenerator as a bean and leaving previous annotations as they were), although it looks like it is being picked up (tested with debugger within allowAssignedIdentifiers method), the generate method is never invoked, resulting in the classic OptimisticLockException.

The latter (removing @GeneratedValue, but leaving the custom annotation) does not cause any difference in the outcome we’re getting. Still getting the missing sequence [sgroup_seq] one.

Any other ideas?

4

We have a test case that proves this works. It doesn’t use a bean, but you were saying it is picked up properly, so there must be an issue in your code somewhere.

The way that these custom annotations work is that they are injected in the constructor of the generator, which you can nicely see when you read the Javadoc of the @IdGeneratorType annotation. So you will have to add a constructor into your SequenceOrAssignedGenerator that accepts this CustomGen and configures the SequenceStyleGenerator accordingly.