My research suggests that this error occurs when something like item1.setOptions(item2.getOptions()) occurs. Solutions generally suggest searching for and removing anything like that. I am never calling Item.setOptions anywhere in my own code, so it seems to me that whatever is causing this must be within Spring GraphQL or JPA code or somewhere else. How do I stop it from causing this error?
I am trying to apply GraphQL to a particular data model with a Many to Many mapping. I have two classes, simplified below:
@Entity
@Data
@NoArgsConstructor
@Table(name="items_table")
public class Item implements Serializable {
private static final long serialVersionUID = -2084220931830648548L;
@Id
@Column(nullable = false)
String id;
@Basic(optional = false)
@Column(nullable = false)
String type;
@ManyToMany
@JoinTable(name="options_table",
joinColumns = @JoinColumn(name="type", referencedColumnName="type"),
inverseJoinColumns = @JoinColumn(name="id", referencedColumnName="id"))
List<Option> options;
}
@Entity
@Data
@NoArgsConstructor
@Table(name="options_table")
public class Option implements Serializable {
private static final long serialVersionUID = 7050760122397397513L;
@Id
@Column(nullable = false)
Long id;
@Basic(optional = false)
@Column(nullable = false)
String type;
}
The GraphQL Schema, again simplified:
type Query {
items: [Item]
}
type Item{
id : Int
type: String
options: [Option]
}
type Option {
id : Int
type: String
}
The Controller class and Service. If I use @SchemaMapping rather than @BatchMapping I do not get this error, but this is a large dataset so that is inefficient.:
@Controller
public class GraphQLController {
@Autowired
private GraphQLService graphqlService;
@QueryMapping
List<Item> items()
{
return graphqlService.getItems();
}
@BatchMapping
Map<Item, List<Option>> options(List<Item> items) {
return graphqlService.getOptionsByTypes(items);
}
}
@Service
public class GraphService {
@Autowired private ItemRepository itemRepo;
@Autowired private OptionRepository optionRepo;
public GraphService() {
super();
}
@Transactional(noRollbackFor=Exception.class)
public List<Item> getItems() {
return StreamSupport.stream(itemRepo.findAll().spliterator(), false).toList();
}
@Transactional(readOnly=true, noRollbackFor=Exception.class)
public Map<Item, List<Option>> getOptionsByTypes(List<Item> items) {
List<String> types = items.stream().map(Item::getType).collect(Collectors.toList());
Map<String, List<Option>> optionsByType= StreamSupport.stream(optionRepo.findByTypeIn(types).spliterator(), false).collect(Collectors.groupingBy(Option::getType));
Map<Item, List<Option>> itemOptionsMap = new HashMap<>();
for (Item item : items) {
List<Option> newList = new ArrayList<>();
newList.addAll(optionsByType.get(item.getType()));
itemOptionsMap.put(item, newList);
}
return itemOptionsMap;
}
}
The repositories only extend JpaRepository and include findByTypeIn(List<String> types) where necessary.
Whenever I do a graphiql query that includes 'items', even if I do not ask for 'options', I get this error:
org.springframework.orm.jpa.JpaSystemException: Found shared references to a collection: my.package.Item.options; nested exception is org.hibernate.HibernateException: Found shared references to a collection: my.package.Item.options
at org.springframework.orm.jpa.vendor.HibernateJpaDialect.convertHibernateAccessException(HibernateJpaDialect.java:331) ~[spring-orm-5.3.21.jar:5.3.21]
at org.springframework.orm.jpa.vendor.HibernateJpaDialect.translateExceptionIfPossible(HibernateJpaDialect.java:233) ~[spring-orm-5.3.21.jar:5.3.21]
at org.springframework.orm.jpa.JpaTransactionManager.doCommit(JpaTransactionManager.java:566) ~[spring-orm-5.3.21.jar:5.3.21]
at org.springframework.transaction.support.AbstractPlatformTransactionManager.processCommit(AbstractPlatformTransactionManager.java:743) ~[spring-tx-5.3.21.jar:5.3.21]
at org.springframework.transaction.support.AbstractPlatformTransactionManager.commit(AbstractPlatformTransactionManager.java:711) ~[spring-tx-5.3.21.jar:5.3.21]
at org.springframework.transaction.interceptor.TransactionAspectSupport.commitTransactionAfterReturning(TransactionAspectSupport.java:654) ~[spring-tx-5.3.21.jar:5.3.21]
at org.springframework.transaction.interceptor.TransactionAspectSupport.invokeWithinTransaction(TransactionAspectSupport.java:407) ~[spring-tx-5.3.21.jar:5.3.21]
at org.springframework.transaction.interceptor.TransactionInterceptor.invoke(TransactionInterceptor.java:119) ~[spring-tx-5.3.21.jar:5.3.21]
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:186) ~[spring-aop-5.3.21.jar:5.3.21]
at org.springframework.aop.framework.CglibAopProxy$CglibMethodInvocation.proceed(CglibAopProxy.java:763) ~[spring-aop-5.3.21.jar:5.3.21]
at org.springframework.aop.framework.CglibAopProxy$DynamicAdvisedInterceptor.intercept(CglibAopProxy.java:708) ~[spring-aop-5.3.21.jar:5.3.21]
at my.package.GraphQLService$$EnhancerBySpringCGLIB$$1b574e58.getItems(<generated>) ~[classes/:na]
at my.package.GraphController.items(GraphController.java:76) ~[classes/:na]
at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[na:na]
at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:77) ~[na:na]
at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[na:na]
at java.base/java.lang.reflect.Method.invoke(Method.java:568) ~[na:na]
at org.springframework.graphql.data.method.InvocableHandlerMethodSupport.doInvoke(InvocableHandlerMethodSupport.java:87) ~[spring-graphql-1.0.0.jar:1.0.0]
at org.springframework.graphql.data.method.annotation.support.DataFetcherHandlerMethod.validateAndInvoke(DataFetcherHandlerMethod.java:191) ~[spring-graphql-1.0.0.jar:1.0.0]
at org.springframework.graphql.data.method.annotation.support.DataFetcherHandlerMethod.invoke(DataFetcherHandlerMethod.java:122) ~[spring-graphql-1.0.0.jar:1.0.0]
at org.springframework.graphql.data.method.annotation.support.AnnotatedControllerConfigurer$SchemaMappingDataFetcher.get(AnnotatedControllerConfigurer.java:497) ~[spring-graphql-1.0.0.jar:1.0.0]
at org.springframework.graphql.execution.ContextDataFetcherDecorator.lambda$get$0(ContextDataFetcherDecorator.java:64) ~[spring-graphql-1.0.0.jar:1.0.0]
at org.springframework.graphql.execution.ReactorContextManager.invokeCallable(ReactorContextManager.java:104) ~[spring-graphql-1.0.0.jar:1.0.0]
at org.springframework.graphql.execution.ContextDataFetcherDecorator.get(ContextDataFetcherDecorator.java:63) ~[spring-graphql-1.0.0.jar:1.0.0]
at org.springframework.boot.actuate.metrics.graphql.GraphQlMetricsInstrumentation.lambda$instrumentDataFetcher$1(GraphQlMetricsInstrumentation.java:98) ~[spring-boot-actuator-2.7.1.jar:2.7.1]
at graphql.execution.ExecutionStrategy.fetchField(ExecutionStrategy.java:279) ~[graphql-java-18.1.jar:na]
at graphql.execution.ExecutionStrategy.resolveFieldWithInfo(ExecutionStrategy.java:210) ~[graphql-java-18.1.jar:na]
at graphql.execution.AsyncExecutionStrategy.execute(AsyncExecutionStrategy.java:60) ~[graphql-java-18.1.jar:na]
at graphql.execution.Execution.executeOperation(Execution.java:160) ~[graphql-java-18.1.jar:na]
at graphql.execution.Execution.execute(Execution.java:106) ~[graphql-java-18.1.jar:na]
at graphql.GraphQL.execute(GraphQL.java:641) ~[graphql-java-18.1.jar:na]
at graphql.GraphQL.lambda$parseValidateAndExecute$11(GraphQL.java:561) ~[graphql-java-18.1.jar:na]
at java.base/java.util.concurrent.CompletableFuture.uniComposeStage(CompletableFuture.java:1187) ~[na:na]
at java.base/java.util.concurrent.CompletableFuture.thenCompose(CompletableFuture.java:2309) ~[na:na]
at graphql.GraphQL.parseValidateAndExecute(GraphQL.java:556) ~[graphql-java-18.1.jar:na]
at graphql.GraphQL.executeAsync(GraphQL.java:524) ~[graphql-java-18.1.jar:na]
at org.springframework.graphql.execution.DefaultExecutionGraphQlService.lambda$execute$2(DefaultExecutionGraphQlService.java:81) ~[spring-graphql-1.0.0.jar:1.0.0]
at reactor.core.publisher.MonoDeferContextual.subscribe(MonoDeferContextual.java:47) ~[reactor-core-3.4.19.jar:3.4.19]
at reactor.core.publisher.InternalMonoOperator.subscribe(InternalMonoOperator.java:64) ~[reactor-core-3.4.19.jar:3.4.19]
at reactor.core.publisher.MonoFlatMap$FlatMapMain.onNext(MonoFlatMap.java:157) ~[reactor-core-3.4.19.jar:3.4.19]
at reactor.core.publisher.FluxOnErrorResume$ResumeSubscriber.onNext(FluxOnErrorResume.java:79) ~[reactor-core-3.4.19.jar:3.4.19]
at reactor.core.publisher.FluxOnErrorResume$ResumeSubscriber.onNext(FluxOnErrorResume.java:79) ~[reactor-core-3.4.19.jar:3.4.19]
at reactor.core.publisher.Operators$MonoSubscriber.complete(Operators.java:1816) ~[reactor-core-3.4.19.jar:3.4.19]
at reactor.core.publisher.MonoFlatMap$FlatMapMain.onNext(MonoFlatMap.java:151) ~[reactor-core-3.4.19.jar:3.4.19]
at reactor.core.publisher.FluxContextWrite$ContextWriteSubscriber.onNext(FluxContextWrite.java:107) ~[reactor-core-3.4.19.jar:3.4.19]
at reactor.core.publisher.FluxMapFuseable$MapFuseableConditionalSubscriber.onNext(FluxMapFuseable.java:299) ~[reactor-core-3.4.19.jar:3.4.19]
at reactor.core.publisher.FluxFilterFuseable$FilterFuseableConditionalSubscriber.onNext(FluxFilterFuseable.java:337) ~[reactor-core-3.4.19.jar:3.4.19]
at reactor.core.publisher.Operators$MonoSubscriber.complete(Operators.java:1816) ~[reactor-core-3.4.19.jar:3.4.19]
at reactor.core.publisher.MonoCollect$CollectSubscriber.onComplete(MonoCollect.java:160) ~[reactor-core-3.4.19.jar:3.4.19]
at reactor.core.publisher.FluxMap$MapSubscriber.onComplete(FluxMap.java:144) ~[reactor-core-3.4.19.jar:3.4.19]
at reactor.core.publisher.FluxPeek$PeekSubscriber.onComplete(FluxPeek.java:260) ~[reactor-core-3.4.19.jar:3.4.19]
at reactor.core.publisher.FluxMap$MapSubscriber.onComplete(FluxMap.java:144) ~[reactor-core-3.4.19.jar:3.4.19]
at reactor.netty.channel.FluxReceive.terminateReceiver(FluxReceive.java:468) ~[reactor-netty-core-1.0.20.jar:1.0.20]
at reactor.netty.channel.FluxReceive.drainReceiver(FluxReceive.java:260) ~[reactor-netty-core-1.0.20.jar:1.0.20]
at reactor.netty.channel.FluxReceive.request(FluxReceive.java:129) ~[reactor-netty-core-1.0.20.jar:1.0.20]
at reactor.core.publisher.FluxMap$MapSubscriber.request(FluxMap.java:164) ~[reactor-core-3.4.19.jar:3.4.19]
at reactor.core.publisher.FluxPeek$PeekSubscriber.request(FluxPeek.java:138) ~[reactor-core-3.4.19.jar:3.4.19]
at reactor.core.publisher.FluxMap$MapSubscriber.request(FluxMap.java:164) ~[reactor-core-3.4.19.jar:3.4.19]
at reactor.core.publisher.MonoCollect$CollectSubscriber.onSubscribe(MonoCollect.java:104) ~[reactor-core-3.4.19.jar:3.4.19]
at reactor.core.publisher.FluxMap$MapSubscriber.onSubscribe(FluxMap.java:92) ~[reactor-core-3.4.19.jar:3.4.19]
at reactor.core.publisher.FluxPeek$PeekSubscriber.onSubscribe(FluxPeek.java:171) ~[reactor-core-3.4.19.jar:3.4.19]
at reactor.core.publisher.FluxMap$MapSubscriber.onSubscribe(FluxMap.java:92) ~[reactor-core-3.4.19.jar:3.4.19]
at reactor.netty.channel.FluxReceive.startReceiver(FluxReceive.java:167) ~[reactor-netty-core-1.0.20.jar:1.0.20]
at reactor.netty.channel.FluxReceive.lambda$subscribe$2(FluxReceive.java:146) ~[reactor-netty-core-1.0.20.jar:1.0.20]
at io.netty.util.concurrent.AbstractEventExecutor.runTask(AbstractEventExecutor.java:174) ~[netty-common-4.1.78.Final.jar:4.1.78.Final]
at io.netty.util.concurrent.AbstractEventExecutor.safeExecute(AbstractEventExecutor.java:167) ~[netty-common-4.1.78.Final.jar:4.1.78.Final]
at io.netty.util.concurrent.SingleThreadEventExecutor.runAllTasks(SingleThreadEventExecutor.java:470) ~[netty-common-4.1.78.Final.jar:4.1.78.Final]
at io.netty.channel.nio.NioEventLoop.run(NioEventLoop.java:503) ~[netty-transport-4.1.78.Final.jar:4.1.78.Final]
at io.netty.util.concurrent.SingleThreadEventExecutor$4.run(SingleThreadEventExecutor.java:997) ~[netty-common-4.1.78.Final.jar:4.1.78.Final]
at io.netty.util.internal.ThreadExecutorMap$2.run(ThreadExecutorMap.java:74) ~[netty-common-4.1.78.Final.jar:4.1.78.Final]
at io.netty.util.concurrent.FastThreadLocalRunnable.run(FastThreadLocalRunnable.java:30) ~[netty-common-4.1.78.Final.jar:4.1.78.Final]
at java.base/java.lang.Thread.run(Thread.java:833) ~[na:na]
Caused by: org.hibernate.HibernateException: Found shared references to a collection: my.package.Item.options
at org.hibernate.engine.internal.Collections.processReachableCollection(Collections.java:188) ~[hibernate-core-5.6.9.Final.jar:5.6.9.Final]
at org.hibernate.event.internal.FlushVisitor.processCollection(FlushVisitor.java:53) ~[hibernate-core-5.6.9.Final.jar:5.6.9.Final]
at org.hibernate.event.internal.AbstractVisitor.processValue(AbstractVisitor.java:104) ~[hibernate-core-5.6.9.Final.jar:5.6.9.Final]
at org.hibernate.event.internal.AbstractVisitor.processValue(AbstractVisitor.java:65) ~[hibernate-core-5.6.9.Final.jar:5.6.9.Final]
at org.hibernate.event.internal.AbstractVisitor.processEntityPropertyValues(AbstractVisitor.java:59) ~[hibernate-core-5.6.9.Final.jar:5.6.9.Final]
at org.hibernate.event.internal.DefaultFlushEntityEventListener.onFlushEntity(DefaultFlushEntityEventListener.java:183) ~[hibernate-core-5.6.9.Final.jar:5.6.9.Final]
at org.hibernate.event.service.internal.EventListenerGroupImpl.fireEventOnEachListener(EventListenerGroupImpl.java:107) ~[hibernate-core-5.6.9.Final.jar:5.6.9.Final]
at org.hibernate.event.internal.AbstractFlushingEventListener.flushEntities(AbstractFlushingEventListener.java:229) ~[hibernate-core-5.6.9.Final.jar:5.6.9.Final]
at org.hibernate.event.internal.AbstractFlushingEventListener.flushEverythingToExecutions(AbstractFlushingEventListener.java:93) ~[hibernate-core-5.6.9.Final.jar:5.6.9.Final]
at org.hibernate.event.internal.DefaultFlushEventListener.onFlush(DefaultFlushEventListener.java:39) ~[hibernate-core-5.6.9.Final.jar:5.6.9.Final]
at org.hibernate.event.service.internal.EventListenerGroupImpl.fireEventOnEachListener(EventListenerGroupImpl.java:107) ~[hibernate-core-5.6.9.Final.jar:5.6.9.Final]
at org.hibernate.internal.SessionImpl.doFlush(SessionImpl.java:1407) ~[hibernate-core-5.6.9.Final.jar:5.6.9.Final]
at org.hibernate.internal.SessionImpl.managedFlush(SessionImpl.java:489) ~[hibernate-core-5.6.9.Final.jar:5.6.9.Final]
at org.hibernate.internal.SessionImpl.flushBeforeTransactionCompletion(SessionImpl.java:3290) ~[hibernate-core-5.6.9.Final.jar:5.6.9.Final]
at org.hibernate.internal.SessionImpl.beforeTransactionCompletion(SessionImpl.java:2425) ~[hibernate-core-5.6.9.Final.jar:5.6.9.Final]
at org.hibernate.engine.jdbc.internal.JdbcCoordinatorImpl.beforeTransactionCompletion(JdbcCoordinatorImpl.java:449) ~[hibernate-core-5.6.9.Final.jar:5.6.9.Final]
at org.hibernate.resource.transaction.backend.jdbc.internal.JdbcResourceLocalTransactionCoordinatorImpl.beforeCompletionCallback(JdbcResourceLocalTransactionCoordinatorImpl.java:183) ~[hibernate-core-5.6.9.Final.jar:5.6.9.Final]
at org.hibernate.resource.transaction.backend.jdbc.internal.JdbcResourceLocalTransactionCoordinatorImpl.access$300(JdbcResourceLocalTransactionCoordinatorImpl.java:40) ~[hibernate-core-5.6.9.Final.jar:5.6.9.Final]
at org.hibernate.resource.transaction.backend.jdbc.internal.JdbcResourceLocalTransactionCoordinatorImpl$TransactionDriverControlImpl.commit(JdbcResourceLocalTransactionCoordinatorImpl.java:281) ~[hibernate-core-5.6.9.Final.jar:5.6.9.Final]
at org.hibernate.engine.transaction.internal.TransactionImpl.commit(TransactionImpl.java:101) ~[hibernate-core-5.6.9.Final.jar:5.6.9.Final]
at org.springframework.orm.jpa.JpaTransactionManager.doCommit(JpaTransactionManager.java:562) ~[spring-orm-5.3.21.jar:5.3.21]
... 69 common frames omitted
CodePudding user response：
The problem is the way your mapping is structured. You can't have a *-to-many association that is based on a column which is not unique. Your Item#options mapping does do that though, so you might have two different Item objects i.e. with different id values, but with the same type value.
Now due to your mapping, these two objects would refer to the same logical collection, in which case you are already in trouble, because that is the illegal "shared references to a collection" which the exception is talking about.
It seems to me that this is an ad-hoc association which is only relevant for your GraphQL endpoint, but not important for regular persistence. So I would suggest you to remove the Item#options association and model this in a DTO then.
I think this is a perfect use case for Blaze-Persistence Entity Views.
I created the library to allow easy mapping between JPA models and custom interface or abstract class defined models, something like Spring Data Projections on steroids. The idea is that you define your target structure(domain model) the way you like and map attributes(getters) via JPQL expressions to the entity model.
A DTO model for your use case could look like the following with Blaze-Persistence Entity-Views:
@EntityView(Item.class)
public interface ItemDto {
@IdMapping
String getId();
String getType();
@Mapping("Option[type = VIEW(type)]")
Set<OptionDto> getOptions();
@EntityView(Option.class)
interface OptionDto {
@IdMapping
Long getId();
String getType();
}
}
Querying is a matter of applying the entity view to a query, the simplest being just a query by id.
ItemDto a = entityViewManager.find(entityManager, ItemDto.class, id);
The Spring Data integration allows you to use it almost like Spring Data Projections: https://persistence.blazebit.com/documentation/entity-view/manual/en_US/index.html#spring-data-features
Page<ItemDto> findAll(Pageable pageable);
The best part is, it will only fetch the state that is actually necessary!
With the various GraphQL integrations, it even supports applying dynamic fetches based on user requested fields.