Issue with Postgres, @MappedSuperclass, generics and enums

Hibernate ORM
1

Hi,

I had a very weird and specific issue today using a parameterized @MappedSuperclass containing an enum field with a Postgres datasource. I’m using the latest Hibernate ORM 6.1.6 with Spring Boot 3.0.

Here’s how it’s triggered:

  • Use a Postgresql data source
  • Have a parameterized @MappedSuperclass class ParameterizedParent<T> { ... }
  • Have an enum type field on this @MappedSuperclass (something like @Enumerated(EnumType.STRING) private MyEnum myEnum;)
  • Have a regular @Entity subclass of the parameterized @MappedSuperclass
  • Generate the DDL (hibernate.hbm2ddl.auto=create/create-drop/update)

The bug does NOT occur when:

  • Using another database like H2 or HSQL (I did not test others)
  • The @MappedSuperclass is not parameterized
  • The enum field is declared on the @Entity class directly instead of the @MappedSuperclass one

The bug still occurs when:

  • Using the pgjdbc-ng Postgres driver instead of the standard one
  • The @Entity does not declare the type parameter (raw usage of generics) on its parent class
  • The enum field is not annotated or annotated with @Enumerated(EnumType.ORDINAL) => the exception become “mapped as 5 but is -3”

A simple workaround is to set the column definition explicitly on the enum field with @Column(columnDefinition = "varchar(255)") (or similar declaration if the enum should be saved as ordinal).

The whole thing is described in this repo, with a bunch of unit tests for each case above and the full exception I get.

Before I open a bug, does anyone have an idea of what went wrong here, and how it could be fixed?

1 Like
2

Sorry, no idea, but thanks for creating the reproducer. Please add the link to the JIRA issue and we will look into it ASAP.

3

Here it is (finally): [HHH-15970] - Hibernate JIRA

1 Like