Pageable Projections Neo4jRepository

[mklopp]

Hello,

I am trying to get Projections to work, as I want to load only some data from neo4j and not all nested relationships and nodes. I got everything to work so far except "Pages".

Consider following example:

Entity:

@Node(primaryLabel = "Entity")
public class Entity {
    @Property(name = some_property)
    private String someProperty;

    @Relationship(type = "some_rel", direction = Relationship.Direction.OUTGOING)
    private List<Entity2> otherEntities;

Projection:

@Value //lombok
public class Entity {
    String someProperty;

Repository:

public interface EntityRepository extends Neo4jRepository<Entity, Long> {
    Optional<MyProjection> findBySomeProperty(String someProperty);
    Page<MyProjection> findAllProjectedBy(Pageable pageable);
}

Now calling findBySomeProperty("value") works like a charm and the related entities do not have to be loaded from the neo4j database (at least I hope so, as this is the goal of projections)

But calling findAllProjectedBy(PageRequest.of(0,20) throws an unexpected error:

java.lang.ClassCastException: class java.util.ArrayList cannot be cast to class org.springframework.data.neo4j.repository.query.EntityInstanceWithSource (java.util.ArrayList is in module java.base of loader 'bootstrap'; org.springframework.data.neo4j.repository.query.EntityInstanceWithSource is in unnamed module of loader 'app')
	at org.springframework.data.neo4j.repository.query.AbstractNeo4jQuery.lambda$execute$2(AbstractNeo4jQuery.java:94) ~[spring-data-neo4j-6.0.3.jar:6.0.3]
	at org.springframework.data.repository.query.ResultProcessor$ChainingConverter.convert(ResultProcessor.java:236) ~[spring-data-commons-2.4.3.jar:2.4.3]
	at org.springframework.data.repository.query.ResultProcessor$ChainingConverter.lambda$and$0(ResultProcessor.java:222) ~[spring-data-commons-2.4.3.jar:2.4.3]
	at org.springframework.data.repository.query.ResultProcessor$ChainingConverter.convert(ResultProcessor.java:236) ~[spring-data-commons-2.4.3.jar:2.4.3]
	at org.springframework.data.repository.query.ResultProcessor.processResult(ResultProcessor.java:170) ~[spring-data-commons-2.4.3.jar:2.4.3]
	at org.springframework.data.neo4j.repository.query.AbstractNeo4jQuery.execute(AbstractNeo4jQuery.java:97) ~[spring-data-neo4j-6.0.3.jar:6.0.3]
	at org.springframework.data.repository.core.support.RepositoryMethodInvoker.doInvoke(RepositoryMethodInvoker.java:137) ~[spring-data-commons-2.4.3.jar:2.4.3]
	at org.springframework.data.repository.core.support.RepositoryMethodInvoker.invoke(RepositoryMethodInvoker.java:121) ~[spring-data-commons-2.4.3.jar:2.4.3]
	at org.springframework.data.repository.core.support.QueryExecutorMethodInterceptor.doInvoke(QueryExecutorMethodInterceptor.java:152) ~[spring-data-commons-2.4.3.jar:2.4.3]
	at org.springframework.data.repository.core.support.QueryExecutorMethodInterceptor.invoke(QueryExecutorMethodInterceptor.java:131) ~[spring-data-commons-2.4.3.jar:2.4.3]
	at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:186) ~[spring-aop-5.3.3.jar:5.3.3]
	at org.springframework.data.projection.DefaultMethodInvokingMethodInterceptor.invoke(DefaultMethodInvokingMethodInterceptor.java:80) ~[spring-data-commons-2.4.3.jar:2.4.3]
	at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:186) ~[spring-aop-5.3.3.jar:5.3.3]
	at org.springframework.transaction.interceptor.TransactionInterceptor$1.proceedWithInvocation(TransactionInterceptor.java:123) ~[spring-tx-5.3.3.jar:5.3.3]
	at org.springframework.transaction.interceptor.TransactionAspectSupport.invokeWithinTransaction(TransactionAspectSupport.java:388) ~[spring-tx-5.3.3.jar:5.3.3]
	at org.springframework.transaction.interceptor.TransactionInterceptor.invoke(TransactionInterceptor.java:119) ~[spring-tx-5.3.3.jar:5.3.3]
	at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:186) ~[spring-aop-5.3.3.jar:5.3.3]
	at org.springframework.dao.support.PersistenceExceptionTranslationInterceptor.invoke(PersistenceExceptionTranslationInterceptor.java:137) ~[spring-tx-5.3.3.jar:5.3.3]
	at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:186) ~[spring-aop-5.3.3.jar:5.3.3]
	at org.springframework.aop.interceptor.ExposeInvocationInterceptor.invoke(ExposeInvocationInterceptor.java:97) ~[spring-aop-5.3.3.jar:5.3.3]
	at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:186) ~[spring-aop-5.3.3.jar:5.3.3]
	at org.springframework.aop.framework.JdkDynamicAopProxy.invoke(JdkDynamicAopProxy.java:215) ~[spring-aop-5.3.3.jar:5.3.3]
	at com.sun.proxy.$Proxy128.findAllProjectedBy(Unknown Source) ~[na:na]

Maybe someone can tell me what I did wrong or how it is supposed to work.

Thank you.

[mklopp]

Still trying to solve this issue. Any help?

[gerrit_meier]

Sorry for the delay.
I tried to reproduce your problem with Spring Boot 2.4.4 (Spring Data Neo4j 6.0.6 / current) and 2.4.3 (6.0.5) but could not find a problem. Maybe you can have a look at neo4j-issues-examples/c-35084 at master · meistermeier/neo4j-issues-examples · GitHub and tell me if there is something different in your code. I tried to keep it as close as possible to the given example.

[mklopp]

Thank you a lot!
I was using Spring Boot 2.4.2.
I downloaded your example and it worked. When I changed the Spring Boot version in your example back to 2.4.2, it threw the same error that I posted above.
I never thought changing from 2.4.2 to 2.4.4 would do the trick.

[gerrit_meier]

And now that you are saying this, I remember that there was something around pageables and projections that got fixed.