从Spring Data JPA 1.4.x升级到更新的版本（例如1.7.1）后，为什么我的中间存储库接口会引起麻烦？

Question

No [ManagedType] was found for the key class [java.lang.Object] in the Metamodel - please verify that the [Managed] class was referenced in persistence.xml using a specific <class>java.lang.Object</class> property or a global <exclude-unlisted-classes>false</exclude-unlisted-classes> element.
       at org.eclipse.persistence.internal.jpa.metamodel.MetamodelImpl.entityEmbeddableManagedTypeNotFound(MetamodelImpl.java:173) ~[org.eclipse.persistence.jpa-2.5.2.jar:na]
       at org.eclipse.persistence.internal.jpa.metamodel.MetamodelImpl.managedType(MetamodelImpl.java:495) ~[org.eclipse.persistence.jpa-2.5.2.jar:na]

It's strange because reverting to Spring Data JPA 1.4.3.RELEASE fixed the problem. But we would like to understand what is causing this. The interface repository we're using looks like this

@Repository
public interface BaseRepository<T, K extends Serializable>
  extends JpaRepository<T, K>,
  QueryDslPredicateExecutor<T> {
}

and

@Repository
public interface PersonRepository extends BaseRepository<Person, Long> { }

In the meantime, we'll use the old version, but I'm not sure where to look in order to fix this. Any ideas?

Answer 1

tl;dr

As stated in the reference documentation , intermediate repository interfaces need to be annotated with @NoRepositoryBean . Generally speaking, Spring Data repositories do not need to be annotated with @Repository .

Details

Spring Data JPA versions until 1.4.x used a lazy instantiation model for repository interfaces. This means that if no one explicitly referred to a particular repository interface, no repository bean was created and thus the generic typing not evaluated.

In Spring Data 1.5 M1 we changed that (more precisely, Spring Data Commons 1.7 M1 - see this ticket , but that is what JPA 1.5 M1 depended on) to align with the default bean instantiation model that's used throughout the Spring container (eager instantiation is the default).

This means, that previously erroneous intermediate interfaces like your BaseRepository now start to fail the context bootstrapped as their generics information is evaluated at startup. As indicated above, the suggested workaround is using @NoRepositoryBean on the intermediate interface as this will cause the interface to be ignored by Spring Data and there will be no attempt to create a Spring bean for it at all.

Answer 2

Do you use BaseRepository somewhere as a bean? If not, maybe remove the @Repository annotation from it, or replace with @NoRepositoryBean