Inconsistency when having multiple MappingContexts in an application vs a single one

[joao-borges]

Hello,

I am upgrading my company applications to spring boot 2.6.6, which includes spring-data-commons 2.6.3.
Doing that, I bumped into this problem: spring-projects/spring-data-rest#2095.

This problem was supposed to be fixed in 2.6.1 version but I am still experiencing it, and after a long debugging journey I might have found the problem.

The inconsistency I found lives in here:

	public PersistentEntity<?, ? extends PersistentProperty<?>> getRequiredPersistentEntity(Class<?> type) {

		Assert.notNull(type, "Domain type must not be null!");

		if (contexts.size() == 1) {
			return contexts.iterator().next().getRequiredPersistentEntity(type);
		}

		return getPersistentEntity(type).orElseThrow(() -> {
			return new MappingException(String.format(
					"Cannot get or create PersistentEntity for type %s! PersistentEntities knows about %s MappingContext instances and therefore cannot identify a single responsible one. Please configure the initialEntitySet through an entity scan using the base package in your configuration to pre initialize contexts.",
					type.getName(), contexts.size()));
		});
	}

When there's a single mapping context, an optimization is done to invoke getRequiredPersistentEntity on that single one.
That works well with the solution made in the other issue reported, a proxy class for an entity is correctly related to its concrete class and everything works fine.

However, when we have multiple contexts, we dive into this method:

	public Optional<PersistentEntity<?, ? extends PersistentProperty<?>>> getPersistentEntity(Class<?> type) {

		for (MappingContext<?, ? extends PersistentProperty<?>> context : contexts) {
			if (context.hasPersistentEntityFor(type)) {
				return Optional.of(context.getRequiredPersistentEntity(type));
			}
		}

		return Optional.empty();
	}

In here, before invoking getRequiredPersistentEntity, it's being called hasPersistentEntityFor with the class being a HibernateProxy.
I am not sure why - but hasPersistentEntityFor is returning false in that situation, preventing the subsequent method to be called.
The other contexts I have are unrelated so they are expected to return false.

Looking at the caller method, this causes an exception that prevents the completion of the request.
But when a single context is involved, no issue happens.

I am attaching 2 simple spring-boot applications that reproduce the inconsistency. One with a single context, one with more than one.
single context
multiple contexts
For both, the problem is reproduced by using the following cURL command:

curl --location --request GET 'localhost:8088/api/test/userGroups?projection=projection'

Using the single-context app, no error will happen. In the multi-context, the error will happen.

I appreciate the time and if you guys are able to look into this please.
Our upgrade to latest spring boot is now blocked.

Thanks

Joao
[email protected]

[odrotbohm]

This suspiciously sounds like a duplicate of #2589, resolved in Spring Data Commons 2.6.4. Would you mind giving a recent version a try?

[joao-borges]

@odrotbohm it works. thanks for looking at it

[odrotbohm]

Happy coding!