SchemaManager

[gavinking]

For testing, it's quite useful to have a programmatic way to perform schema management, instead of messing about with properties and creating/destroying the EntityManagerFactory.

[gavinking]

As possible starting point for discussion, here's an API we recently added to Hibernate:

public interface SchemaManager {
    /**
     * Export database objects mapped by Hibernate entities.
     *
     * @param createSchemas if {@code true}, attempt to create schemas,
     *                      otherwise, assume the schemas already exist
     */
    void exportMappedObjects(boolean createSchemas);

    /**
     * Drop database objects mapped by Hibernate entities, undoing the
     * {@linkplain #exportMappedObjects(boolean) previous export}.
     * <p>
     * @param dropSchemas if {@code true}, drop schemas,
     *                    otherwise, leave them be
     */
    void dropMappedObjects(boolean dropSchemas);

    /**
     * Validate that the database objects mapped by Hibernate entities
     * have the expected definitions.
     */
    void validateMappedObjects();

    /**
     * Truncate the database tables mapped by Hibernate entities, and
     * then re-import initial data from any configured
     * {@linkplain org.hibernate.cfg.AvailableSettings#JAKARTA_HBM2DDL_LOAD_SCRIPT_SOURCE
     * load script}.
     */
    void truncateMappedObjects();
}

Of course, validateMappedObjects() and truncateMappedObjects() might not be features you folks want in the JPA spec, since JPA doesn't have any such functionality defined today.

[gavinking]

Folks, please review https://github.com/jakartaee/persistence/pull/431

[gavinking]

If we decide to do this, and if SchemaManager has a validate() method, then I think we should also list "validate" as one of the allowed values for schema export config. It would have fairly weakly-defined semantics (and providers could even just ignore it) but even so it's worth enumerating I believe.

(Note that validate is a lot less problematic than update, so I'm not really contradicting myself here.)