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POLazyInitializationException in JPA and Hibernate
 

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  1. POLazyInitializationException in JPA and Hibernate
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    <p>I know that this question has been ask numerous times here and across the internet and I have read through many of those answers but I still don't understand the proper way to solve this problem. I am experimenting with Spring MVC and JPA and every time I access a lazily loaded property I get a LazyInitializationException. </p> <p>Here is some of the code I am experimenting with:</p> <pre><code>@Repository public class MyDAO { private static final Logger logger = LoggerFactory.getLogger(MyDAO.class); @PersistenceContext private EntityManager em; @Transactional public void logDOI() { DOI myDOI = em.find(DOI.class, Long.valueOf(1)); // This line gives the expected output logger.info("Fetched DOI: " + myDOI.getDoiKey()); // This line throws the LazyInitalizationException for(DOIMembership m : myDOI.getDoiMemberships()) { logger.info("Got DOI Membership id: " + m.getId()); } } } </code></pre> <p>The entity I am accessing:</p> <pre><code>@Entity @Table(name="DOI") public class DOI implements Serializable { private static final long serialVersionUID = 1L; @Id @SequenceGenerator(name="DOI_ID_GENERATOR", sequenceName="DOI_SEQ") @GeneratedValue(strategy=GenerationType.SEQUENCE, generator="DOI_ID_GENERATOR") private long id; // Other properties omitted //bi-directional many-to-one association to DOIMembership @OneToMany(mappedBy="doi", fetch=FetchType.LAZY) private Set&lt;DOIMembership&gt; doiMemberships; public DOI() { } public long getId() { return this.id; } public void setId(long id) { this.id = id; } // Other Accessors Omitted } </code></pre> <p>The entity referenced from DOI</p> <pre><code>@Entity @Table(name="DOI_MEMBERSHIP") public class DOIMembership implements Serializable { private static final long serialVersionUID = 1L; @Id @SequenceGenerator(name="DOI_MEMBERSHIP_ID_GENERATOR", sequenceName="DOI_MEMBERSHIP_SEQ") @GeneratedValue(strategy=GenerationType.SEQUENCE, generator="DOI_MEMBERSHIP_ID_GENERATOR") private long id; //bi-directional many-to-one association to DOI @ManyToOne(fetch=FetchType.LAZY) @JoinColumn(name="DOI_ID") private DOI doi; @Column(name="GROUP_ID") private BigDecimal groupId; @Column(name="DATA_SET") private BigDecimal dataSetId; public DOIMembership() { } public BigDecimal getGroupId() { return groupId; } public BigDecimal getDataSetId() { return dataSetId; } public void setDataSetId(BigDecimal dataSetId) { this.dataSetId = dataSetId; } public void setGroupId(BigDecimal groupId) { this.groupId = groupId; } public long getId() { return this.id; } public void setId(long id) { this.id = id; } public DOI getDoi() { return this.doi; } public void setDoi(DOI doi) { this.doi = doi; } } </code></pre> <p>The Spring MVC Controller:</p> <pre><code>@Controller @RequestMapping("/summary") public class DOISummaryController { @Autowired MyDAO myDAO; @RequestMapping() public String DOISummary() { myDAO.logDOI(); return "home"; } } </code></pre> <p>My Spring configuration:</p> <pre><code>&lt;?xml version="1.0" encoding="UTF-8"?&gt; &lt;beans xmlns="http://www.springframework.org/schema/beans" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:context="http://www.springframework.org/schema/context" xmlns:task="http://www.springframework.org/schema/task" xmlns:tx="http://www.springframework.org/schema/tx" xsi:schemaLocation="http://www.springframework.org/schema/tx http://www.springframework.org/schema/tx/spring-tx-3.1.xsd http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-3.1.xsd http://www.springframework.org/schema/task http://www.springframework.org/schema/task/spring-task-3.0.xsd http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-3.1.xsd"&gt; &lt;!-- Root Context: defines shared resources visible to all other web components --&gt; &lt;context:property-placeholder location="WEB-INF/spring/root-context.properties, WEB-INF/spring/datasource-context.properties" /&gt; &lt;bean id="dataSource" class="org.apache.commons.dbcp.BasicDataSource" destroy-method="close"&gt; &lt;property name="driverClassName"&gt; &lt;value&gt;oracle.jdbc.driver.OracleDriver&lt;/value&gt; &lt;/property&gt; &lt;property name="url"&gt; &lt;value&gt;${Url}&lt;/value&gt; &lt;/property&gt; &lt;property name="username"&gt; &lt;value&gt;${Username}&lt;/value&gt; &lt;/property&gt; &lt;property name="password"&gt; &lt;value&gt;${Password}&lt;/value&gt; &lt;/property&gt; &lt;/bean&gt; &lt;bean id="emf" class="org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean"&gt; &lt;property name="dataSource" ref="dataSource" /&gt; &lt;property name="jpaVendorAdapter"&gt; &lt;bean class="org.springframework.orm.jpa.vendor.HibernateJpaVendorAdapter" /&gt; &lt;/property&gt; &lt;property name="packagesToScan" value="org.myorg.doi.domain" /&gt; &lt;property name="jpaProperties"&gt; &lt;props&gt; &lt;prop key="hibernate.dialect"&gt; org.hibernate.dialect.Oracle10gDialect &lt;/prop&gt; &lt;prop key="hibernate.max_fetch_depth"&gt;3&lt;/prop&gt; &lt;prop key="hibernate.jdbc.fetch_size"&gt;50&lt;/prop&gt; &lt;prop key="hibernate.jdbc.batch_size"&gt;10&lt;/prop&gt; &lt;prop key="hibernate.show_sql"&gt;true&lt;/prop&gt; &lt;/props&gt; &lt;/property&gt; &lt;/bean&gt; &lt;bean id="transactionManager" class="org.springframework.orm.jpa.JpaTransactionManager"&gt; &lt;property name="entityManagerFactory" ref="emf" /&gt; &lt;/bean&gt; &lt;tx:annotation-driven transaction-manager="transactionManager" /&gt; &lt;context:annotation-config /&gt; &lt;task:annotation-driven /&gt; &lt;context:component-scan base-package="org.myorg.doi" /&gt; &lt;/beans&gt; </code></pre> <p>And a stack trace, as requested:</p> <pre><code>SEVERE: Servlet.service() for servlet [appServlet] in context with path [/DOI] threw exception [Request processing failed; nested exception is org.hibernate.LazyInitializationException: could not initialize proxy - no Session] with root cause org.hibernate.LazyInitializationException: could not initialize proxy - no Session at org.hibernate.collection.internal.AbstractPersistentCollection.initialize(AbstractPersistentCollection.java:430) at org.hibernate.collection.internal.AbstractPersistentCollection.read(AbstractPersistentCollection.java:121) at org.hibernate.collection.internal.PersistentSet.iterator(PersistentSet.java:180) at org.myorg.doi.dao.MyDAO.logDOI(MyDAO.java:27) at org.myorg.doi.web.DOISummaryController.DOISummary(DOISummaryController.java:29) at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39) at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25) at java.lang.reflect.Method.invoke(Method.java:597) at org.springframework.web.method.support.InvocableHandlerMethod.invoke(InvocableHandlerMethod.java:213) at org.springframework.web.method.support.InvocableHandlerMethod.invokeForRequest(InvocableHandlerMethod.java:126) at org.springframework.web.servlet.mvc.method.annotation.ServletInvocableHandlerMethod.invokeAndHandle(ServletInvocableHandlerMethod.java:96) at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.invokeHandlerMethod(RequestMappingHandlerAdapter.java:617) at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.handleInternal(RequestMappingHandlerAdapter.java:578) at org.springframework.web.servlet.mvc.method.AbstractHandlerMethodAdapter.handle(AbstractHandlerMethodAdapter.java:80) at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:923) at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:852) at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:882) at org.springframework.web.servlet.FrameworkServlet.doGet(FrameworkServlet.java:778) at javax.servlet.http.HttpServlet.service(HttpServlet.java:621) at javax.servlet.http.HttpServlet.service(HttpServlet.java:722) at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:305) at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210) at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:225) at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:123) at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:472) at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:168) at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:98) at org.apache.catalina.valves.AccessLogValve.invoke(AccessLogValve.java:927) at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:118) at com.springsource.insight.collection.tcserver.request.HttpRequestOperationCollectionValve.traceNextValve(HttpRequestOperationCollectionValve.java:116) at com.springsource.insight.collection.tcserver.request.HttpRequestOperationCollectionValve.invoke(HttpRequestOperationCollectionValve.java:98) at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:407) at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1001) at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:585) at org.apache.tomcat.util.net.JIoEndpoint$SocketProcessor.run(JIoEndpoint.java:310) at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExecutor.java:886) at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:908) at java.lang.Thread.run(Thread.java:680) </code></pre> <p>I you can see, I am trying to use pure JPA and only using Hibernate as a JPA provider.</p> <p>I understand that the exception is caused by the session being detached from the entity. But, I thought that wouldn't happen if we are currently in a transaction, which should be the case since the logDOI method is annotated with @Transactional.</p> <p>Of course, everything works perfectly if I change the FetchType to EAGER but it seems that I shouldn't have to do that.</p> <p>I am also aware of OpenEntityManagerInViewFilter but it seems that I shouldn't have to use that either if I keep all access to my entities in a DAO annotated with @Transactional (or through some other means that I'm not aware of).</p> <p>I think that I might be approaching this problem incorrectly but I don't know what the correct approach is. How is one supposed to effectively use lazily loaded properties?</p>
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    1. COCould you post a stacktrace?
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    2. COIt seems to be related to get the current Hibernate Session. Did you check you inject correctly the Hibernate Session in your configuration? You ... have the annotation `@Repository` in new version of Spring Framework, I use it for some DAO.
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    3. COI think it is the same that `@Entity` you already use. Then, you should check that the deepth you have set in JPA properties are enough deep to load any `@Autowired` dependencies.
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