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I want to do LAZY loading in a OneToMany Relation in JPA.

The Problem is, that when i want to acces the LAZY loaded Attribute i get a exception. I know that i have to be in a Transaction when trying to access the attribute. But it seems like the Transaction is not open. This is the exception:

org.hibernate.LazyInitializationException: failed to lazily initialize a collection of role: de.recipemanager.recipe.data.Recipe.ingredients, could not initialize proxy - no Session at org.hibernate.collection.internal.AbstractPersistentCollection.throwLazyInitializationException(AbstractPersistentCollection.java:566) at org.hibernate.collection.internal.AbstractPersistentCollection.withTemporarySessionIfNeeded(AbstractPersistentCollection.java:186) at org.hibernate.collection.internal.AbstractPersistentCollection.initialize(AbstractPersistentCollection.java:545) at org.hibernate.collection.internal.AbstractPersistentCollection.read(AbstractPersistentCollection.java:124) at org.hibernate.collection.internal.PersistentBag.iterator(PersistentBag.java:266) at de.recipemanager.recipe.web.IngredientDTOList.<init>(IngredientDTOList.java:27) at de.recipemanager.recipe.web.RecipeDTO.<init>(RecipeDTO.java:28) at de.recipemanager.recipe.web.RecipeDTOServiceImpl.get(RecipeDTOServiceImpl.java:22) at de.recipemanager.recipe.web.RecipeController.get(RecipeController.java:32) at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57) at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) at java.lang.reflect.Method.invoke(Method.java:606) at org.springframework.web.method.support.InvocableHandlerMethod.invoke(InvocableHandlerMethod.java:219) at org.springframework.web.method.support.InvocableHandlerMethod.invokeForRequest(InvocableHandlerMethod.java:132) at org.springframework.web.servlet.mvc.method.annotation.ServletInvocableHandlerMethod.invokeAndHandle(ServletInvocableHandlerMethod.java:104) at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.invokeHandleMethod(RequestMappingHandlerAdapter.java:745) at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.handleInternal(RequestMappingHandlerAdapter.java:686) at org.springframework.web.servlet.mvc.method.AbstractHandlerMethodAdapter.handle(AbstractHandlerMethodAdapter.java:80) at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:925) at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:856) at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:936) at org.springframework.web.servlet.FrameworkServlet.doGet(FrameworkServlet.java:827) at javax.servlet.http.HttpServlet.service(HttpServlet.java:735) at org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:812) at javax.servlet.http.HttpServlet.service(HttpServlet.java:848) at org.eclipse.jetty.servlet.ServletHolder.handle(ServletHolder.java:594) at org.eclipse.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1366) at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:330) at org.springframework.security.web.access.intercept.FilterSecurityInterceptor.invoke(FilterSecurityInterceptor.java:118) at org.springframework.security.web.access.intercept.FilterSecurityInterceptor.doFilter(FilterSecurityInterceptor.java:84) at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342) at org.springframework.security.web.access.ExceptionTranslationFilter.doFilter(ExceptionTranslationFilter.java:113) at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342) at org.springframework.security.web.session.SessionManagementFilter.doFilter(SessionManagementFilter.java:103) at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342) at org.springframework.security.web.authentication.AnonymousAuthenticationFilter.doFilter(AnonymousAuthenticationFilter.java:113) at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342) at org.springframework.security.web.servletapi.SecurityContextHolderAwareRequestFilter.doFilter(SecurityContextHolderAwareRequestFilter.java:150) at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342) at org.springframework.security.web.savedrequest.RequestCacheAwareFilter.doFilter(RequestCacheAwareFilter.java:45) at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342) at org.springframework.security.web.authentication.www.BasicAuthenticationFilter.doFilter(BasicAuthenticationFilter.java:201) at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342) at org.springframework.security.web.authentication.logout.LogoutFilter.doFilter(LogoutFilter.java:105) at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342) at org.springframework.security.web.context.SecurityContextPersistenceFilter.doFilter(SecurityContextPersistenceFilter.java:87) at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342) at org.springframework.security.web.FilterChainProxy.doFilterInternal(FilterChainProxy.java:192) at org.springframework.security.web.FilterChainProxy.doFilter(FilterChainProxy.java:160) at org.springframework.web.filter.DelegatingFilterProxy.invokeDelegate(DelegatingFilterProxy.java:346) at org.springframework.web.filter.DelegatingFilterProxy.doFilter(DelegatingFilterProxy.java:259) at org.eclipse.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1337) at org.eclipse.jetty.servlet.ServletHandler.doHandle(ServletHandler.java:484) at org.eclipse.jetty.server.handler.ScopedHandler.handle(ScopedHandler.java:119) at org.eclipse.jetty.security.SecurityHandler.handle(SecurityHandler.java:524) at org.eclipse.jetty.server.session.SessionHandler.doHandle(SessionHandler.java:233) at org.eclipse.jetty.server.handler.ContextHandler.doHandle(ContextHandler.java:1065) at org.eclipse.jetty.servlet.ServletHandler.doScope(ServletHandler.java:413) at org.eclipse.jetty.server.session.SessionHandler.doScope(SessionHandler.java:192) at org.eclipse.jetty.server.handler.ContextHandler.doScope(ContextHandler.java:999) at org.eclipse.jetty.server.handler.ScopedHandler.handle(ScopedHandler.java:117) at org.eclipse.jetty.server.handler.ContextHandlerCollection.handle(ContextHandlerCollection.java:250) at org.eclipse.jetty.server.handler.HandlerCollection.handle(HandlerCollection.java:149) at org.eclipse.jetty.server.handler.HandlerWrapper.handle(HandlerWrapper.java:111) at org.eclipse.jetty.server.Server.handle(Server.java:351) at org.eclipse.jetty.server.AbstractHttpConnection.handleRequest(AbstractHttpConnection.java:454) at org.eclipse.jetty.server.AbstractHttpConnection.headerComplete(AbstractHttpConnection.java:890) at org.eclipse.jetty.server.AbstractHttpConnection$RequestHandler.headerComplete(AbstractHttpConnection.java:944) at org.eclipse.jetty.http.HttpParser.parseNext(HttpParser.java:634) at org.eclipse.jetty.http.HttpParser.parseAvailable(HttpParser.java:230) at org.eclipse.jetty.server.AsyncHttpConnection.handle(AsyncHttpConnection.java:77) at org.eclipse.jetty.io.nio.SelectChannelEndPoint.handle(SelectChannelEndPoint.java:609) at org.eclipse.jetty.io.nio.SelectChannelEndPoint$1.run(SelectChannelEndPoint.java:45) at org.eclipse.jetty.util.thread.QueuedThreadPool.runJob(QueuedThreadPool.java:599) at org.eclipse.jetty.util.thread.QueuedThreadPool$3.run(QueuedThreadPool.java:534) at java.lang.Thread.run(Thread.java:724) 2013-10-10 21:17:53.427:WARN:oejs.ServletHandler:/api/recipes/1 org.hibernate.LazyInitializationException: failed to lazily initialize a collection of role: de.recipemanager.recipe.data.Recipe.ingredients, could not initialize proxy - no Session at org.hibernate.collection.internal.AbstractPersistentCollection.throwLazyInitializationException(AbstractPersistentCollection.java:566) at org.hibernate.collection.internal.AbstractPersistentCollection.withTemporarySessionIfNeeded(AbstractPersistentCollection.java:186) at org.hibernate.collection.internal.AbstractPersistentCollection.initialize(AbstractPersistentCollection.java:545) at org.hibernate.collection.internal.AbstractPersistentCollection.read(AbstractPersistentCollection.java:124) at org.hibernate.collection.internal.PersistentBag.iterator(PersistentBag.java:266) at de.recipemanager.recipe.web.IngredientDTOList.<init>(IngredientDTOList.java:27) at de.recipemanager.recipe.web.RecipeDTO.<init>(RecipeDTO.java:28) at de.recipemanager.recipe.web.RecipeDTOServiceImpl.get(RecipeDTOServiceImpl.java:22) at de.recipemanager.recipe.web.RecipeController.get(RecipeController.java:32) at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57) at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) at java.lang.reflect.Method.invoke(Method.java:606) at org.springframework.web.method.support.InvocableHandlerMethod.invoke(InvocableHandlerMethod.java:219) at org.springframework.web.method.support.InvocableHandlerMethod.invokeForRequest(InvocableHandlerMethod.java:132) at org.springframework.web.servlet.mvc.method.annotation.ServletInvocableHandlerMethod.invokeAndHandle(ServletInvocableHandlerMethod.java:104) at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.invokeHandleMethod(RequestMappingHandlerAdapter.java:745) at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.handleInternal(RequestMappingHandlerAdapter.java:686) at org.springframework.web.servlet.mvc.method.AbstractHandlerMethodAdapter.handle(AbstractHandlerMethodAdapter.java:80) at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:925) at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:856) at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:936) at org.springframework.web.servlet.FrameworkServlet.doGet(FrameworkServlet.java:827) at javax.servlet.http.HttpServlet.service(HttpServlet.java:735) at org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:812) at javax.servlet.http.HttpServlet.service(HttpServlet.java:848) at org.eclipse.jetty.servlet.ServletHolder.handle(ServletHolder.java:594) at org.eclipse.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1366) at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:330) at org.springframework.security.web.access.intercept.FilterSecurityInterceptor.invoke(FilterSecurityInterceptor.java:118) at org.springframework.security.web.access.intercept.FilterSecurityInterceptor.doFilter(FilterSecurityInterceptor.java:84) at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342) at org.springframework.security.web.access.ExceptionTranslationFilter.doFilter(ExceptionTranslationFilter.java:113) at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342) at org.springframework.security.web.session.SessionManagementFilter.doFilter(SessionManagementFilter.java:103) at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342) at org.springframework.security.web.authentication.AnonymousAuthenticationFilter.doFilter(AnonymousAuthenticationFilter.java:113) at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342) at org.springframework.security.web.servletapi.SecurityContextHolderAwareRequestFilter.doFilter(SecurityContextHolderAwareRequestFilter.java:150) at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342) at org.springframework.security.web.savedrequest.RequestCacheAwareFilter.doFilter(RequestCacheAwareFilter.java:45) at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342) at org.springframework.security.web.authentication.www.BasicAuthenticationFilter.doFilter(BasicAuthenticationFilter.java:201) at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342) at org.springframework.security.web.authentication.logout.LogoutFilter.doFilter(LogoutFilter.java:105) at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342) at org.springframework.security.web.context.SecurityContextPersistenceFilter.doFilter(SecurityContextPersistenceFilter.java:87) at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342) at org.springframework.security.web.FilterChainProxy.doFilterInternal(FilterChainProxy.java:192) at org.springframework.security.web.FilterChainProxy.doFilter(FilterChainProxy.java:160) at org.springframework.web.filter.DelegatingFilterProxy.invokeDelegate(DelegatingFilterProxy.java:346) at org.springframework.web.filter.DelegatingFilterProxy.doFilter(DelegatingFilterProxy.java:259) at org.eclipse.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1337) at org.eclipse.jetty.servlet.ServletHandler.doHandle(ServletHandler.java:484) at org.eclipse.jetty.server.handler.ScopedHandler.handle(ScopedHandler.java:119) at org.eclipse.jetty.security.SecurityHandler.handle(SecurityHandler.java:524) at org.eclipse.jetty.server.session.SessionHandler.doHandle(SessionHandler.java:233) at org.eclipse.jetty.server.handler.ContextHandler.doHandle(ContextHandler.java:1065) at org.eclipse.jetty.servlet.ServletHandler.doScope(ServletHandler.java:413) at org.eclipse.jetty.server.session.SessionHandler.doScope(SessionHandler.java:192) at org.eclipse.jetty.server.handler.ContextHandler.doScope(ContextHandler.java:999) at org.eclipse.jetty.server.handler.ScopedHandler.handle(ScopedHandler.java:117) at org.eclipse.jetty.server.handler.ContextHandlerCollection.handle(ContextHandlerCollection.java:250) at org.eclipse.jetty.server.handler.HandlerCollection.handle(HandlerCollection.java:149) at org.eclipse.jetty.server.handler.HandlerWrapper.handle(HandlerWrapper.java:111) at org.eclipse.jetty.server.Server.handle(Server.java:351) at org.eclipse.jetty.server.AbstractHttpConnection.handleRequest(AbstractHttpConnection.java:454) at org.eclipse.jetty.server.AbstractHttpConnection.headerComplete(AbstractHttpConnection.java:890) at org.eclipse.jetty.server.AbstractHttpConnection$RequestHandler.headerComplete(AbstractHttpConnection.java:944) at org.eclipse.jetty.http.HttpParser.parseNext(HttpParser.java:634) at org.eclipse.jetty.http.HttpParser.parseAvailable(HttpParser.java:230) at org.eclipse.jetty.server.AsyncHttpConnection.handle(AsyncHttpConnection.java:77) at org.eclipse.jetty.io.nio.SelectChannelEndPoint.handle(SelectChannelEndPoint.java:609) at org.eclipse.jetty.io.nio.SelectChannelEndPoint$1.run(SelectChannelEndPoint.java:45) at org.eclipse.jetty.util.thread.QueuedThreadPool.runJob(QueuedThreadPool.java:599) at org.eclipse.jetty.util.thread.QueuedThreadPool$3.run(QueuedThreadPool.java:534) at java.lang.Thread.run(Thread.java:724)

The Entity: 

@Entity(name = "recipe") public class Recipe { @Id @GeneratedValue private Long id; private String name; private Integer duration; @Enumerated(EnumType.STRING) private Difficulty difficulty; @OneToMany(fetch = FetchType.LAZY, cascade = CascadeType.ALL, orphanRemoval = true, mappedBy = "recipe") List<Ingredient> ingredients;

The code where the exception is thrown:

@Service @Transactional public class RecipeServiceImpl implements RecipeService { private final RecipeRepository recipeRepository; @Autowired public RecipeServiceImpl(RecipeRepository recipeRepository) { this.recipeRepository = recipeRepository; } @Override public Recipe get(Long id) { Recipe recipe = recipeRepository.findOne(id); if(recipe == null) { throw new EntityNotFoundException("Recipe with id: " + id + " was not found."); } recipe.getIngredients(); return recipe; }

And my Spring config:

@Configuration @ComponentScan(basePackages = "de.recipemanager") @EnableWebMvc public class ApplicationContext { } @Configuration @PropertySource("classpath:application.properties") @EnableJpaRepositories(basePackages = "de.recipemanager") @EnableTransactionManagement public class JPAContext { private static final String PROPERTY_NAME_DATABASE_DRIVER = "db.driver"; private static final String PROPERTY_NAME_DATABASE_URL = "db.url"; private static final String PROPERTY_NAME_DATABASE_USERNAME = "db.username"; private static final String PROPERTY_NAME_DATABASE_PASSWORD = "db.password"; private static final String PROPERTY_NAME_ENTITYMANAGER_PACKAGES_TO_SCAN = "entitymanager.packages.to.scan"; private static final String PROPERTY_NAME_HIBERNATE_DIALECT = "hibernate.dialect"; private static final String PROPERTY_NAME_HIBERNATE_FORMAT_SQL = "hibernate.format_sql"; private static final String PROPERTY_NAME_HIBERNATE_NAMING_STRATEGY = "hibernate.ejb.naming_strategy"; private static final String PROPERTY_NAME_HIBERNATE_SHOW_SQL = "hibernate.show_sql"; private static final String PROPERTY_NAME_HIBERNATE_AUTO = "hibernate.hbm2ddl.auto"; @Resource private Environment environment; @Bean public DataSource dataSource() throws PropertyVetoException { ComboPooledDataSource dataSource = new ComboPooledDataSource(); dataSource.setDriverClass(environment.getRequiredProperty(PROPERTY_NAME_DATABASE_DRIVER)); dataSource.setJdbcUrl(environment.getRequiredProperty(PROPERTY_NAME_DATABASE_URL)); dataSource.setUser(environment.getRequiredProperty(PROPERTY_NAME_DATABASE_USERNAME)); dataSource.setPassword(environment.getRequiredProperty(PROPERTY_NAME_DATABASE_PASSWORD)); return dataSource; } @Bean public LocalContainerEntityManagerFactoryBean entityManagerFactory() throws ClassNotFoundException, PropertyVetoException { LocalContainerEntityManagerFactoryBean entityManagerFactoryBean = new LocalContainerEntityManagerFactoryBean(); entityManagerFactoryBean.setDataSource(dataSource()); entityManagerFactoryBean.setPackagesToScan( environment.getRequiredProperty(PROPERTY_NAME_ENTITYMANAGER_PACKAGES_TO_SCAN)); entityManagerFactoryBean.setPersistenceProviderClass(HibernatePersistence.class); Properties jpaProperties = new Properties(); jpaProperties.put(PROPERTY_NAME_HIBERNATE_DIALECT, environment.getRequiredProperty(PROPERTY_NAME_HIBERNATE_DIALECT)); jpaProperties.put(PROPERTY_NAME_HIBERNATE_AUTO, environment.getRequiredProperty(PROPERTY_NAME_HIBERNATE_AUTO)); jpaProperties.put(PROPERTY_NAME_HIBERNATE_FORMAT_SQL, environment.getRequiredProperty(PROPERTY_NAME_HIBERNATE_FORMAT_SQL)); jpaProperties.put(PROPERTY_NAME_HIBERNATE_NAMING_STRATEGY, environment.getRequiredProperty(PROPERTY_NAME_HIBERNATE_NAMING_STRATEGY)); jpaProperties.put(PROPERTY_NAME_HIBERNATE_SHOW_SQL, environment.getRequiredProperty(PROPERTY_NAME_HIBERNATE_SHOW_SQL)); entityManagerFactoryBean.setJpaProperties(jpaProperties); return entityManagerFactoryBean; } @Bean public JpaTransactionManager transactionManager() throws ClassNotFoundException, PropertyVetoException { JpaTransactionManager transactionManager = new JpaTransactionManager(); transactionManager.setEntityManagerFactory(entityManagerFactory().getObject()); return transactionManager; } }

I hope someone can help my figure out the solution for my problem, and sorry for my bad english.

Solution

I could get it work by calling the size() attribute of the Ingredientslist.

@Service @Transactional public class RecipeServiceImpl implements RecipeService { private final RecipeRepository recipeRepository; @Autowired public RecipeServiceImpl(RecipeRepository recipeRepository) { this.recipeRepository = recipeRepository; } @Override public Recipe get(Long id) { Recipe recipe = recipeRepository.findOne(id); if(recipe == null) { throw new EntityNotFoundException("Recipe with id: " + id + " was not found."); } recipe.getIngredients().size(); //Needed to fetch the Ingredients in the open Transaction. return recipe; }
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1 Answer 1

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Once you leave this @Transactional method

@Override public Recipe get(Long id) { Recipe recipe = recipeRepository.findOne(id); if(recipe == null) { throw new EntityNotFoundException("Recipe with id: " + id + " was not found."); } recipe.getIngredients(); return recipe; }

The TransactionManager commits/rollsback the transaction and closes the session. As such, for any entities that were lazy loaded, the Session object that was attached is either null or is closed. Those entities cannot therefore be loaded and hibernate throws an Exception. You will need to either put a broader Session scope, possibly with an OpenSessionInViewFilter, eagerly load your entities, or force some of their initializations (the ones you need) inside the @Transactional method.

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5 Comments

But i thought that with the recipe.getIngredients(); i force the initialization of the List?
@DavidSchilling Ah, that won't force it. That'll get an instance of type PersistentList. You can either call size() on the list (I think), or Hibernate.initialize(recipe.getIngredients());.
@SotiriosDelimanolis I'm sure this works all fine and great, but it generates 2 queries correct? I feel like there should be a way to easily do this in 1 query..that or JPA is really lacking
@DavidSchilling I guess another option (way more verbose but would improve efficiency) is to create 2 entity classes, one not containing the ingredients, and one containing them. And then choose when to use which entity class.
@CameronAskew I'm not exactly sure how many it would be and I don't think JPA specifies that. I think the proper solution in that case is to eagerly load the entities.

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