Hibernate Joined Table strategy Polymorphism does not work due to column not found

Question

I am new to Spring MVC and Hibernate. As titled, I do not know how to fix this bug.

I have a root entity Task defined as follows:

@Entity
@Inheritance(strategy = InheritanceType.JOINED)
@Table(name="_Task")
@DiscriminatorColumn(name = "task_type")
@Polymorphism(type = PolymorphismType.EXPLICIT)
@Getter @Setter @NoArgsConstructor 
public class Task {
    @Id
    @GeneratedValue(strategy=GenerationType.IDENTITY)
    @Column(nullable=false,unique=true)
    private long id;

    private String name;

    private String date;

    @Enumerated(EnumType.STRING)
    private Progress progress;

    @Enumerated(EnumType.STRING)
    private Stage stage;

    @Enumerated(EnumType.STRING)
    private Priority priority;

    private int quality;

    @OneToOne
    private User user;

    @OneToOne
    private Product product;

    }
}

And I have two subclasses OTask(other task) and PTask(Produce Task) defined as follows:

@Entity
@PrimaryKeyJoinColumn(name = "taskid")
@Table(name="_ptask")
@DiscriminatorValue("produce")
@Getter @Setter @NoArgsConstructor 
public class PTask extends Task{


    @OneToMany(fetch = FetchType.EAGER,mappedBy="ptask")
    @Column(nullable=true)
    private List<OTask> stasks;

    @OneToMany(fetch = FetchType.EAGER,mappedBy="ptask")
    @Column(nullable=true)
    private List<OTask> prtasks;

    @OneToMany(fetch = FetchType.EAGER,mappedBy="ptask")
    @Column(nullable=true)
    private List<OTask> satasks;

}


@Entity
@PrimaryKeyJoinColumn(name = "taskid")
@Table(name="_otask")
@DiscriminatorValue("other")
@Getter @Setter @NoArgsConstructor 
public class OTask extends Task{

    @ManyToOne
    @JoinColumn(name="ptask_id", nullable=false)
    private PTask ptask;

}

The column 'task_id' not found error occurred when I use Task Dao to get task list.

@SuppressWarnings("unchecked")
public List<Task> getTaskList() {

    Session s = this.sessionFactory.getCurrentSession();

    return (List<Task>) s.createSQLQuery("select _task.* FROM _task;").addEntity(Task.class).list();

}

Here is the error messages:

java.sql.SQLException: Column 'ptask_id' not found. at com.mysql.cj.jdbc.exceptions.SQLError.createSQLException(SQLError.java:129) at com.mysql.cj.jdbc.exceptions.SQLError.createSQLException(SQLError.java:97) at com.mysql.cj.jdbc.exceptions.SQLError.createSQLException(SQLError.java:89) at com.mysql.cj.jdbc.exceptions.SQLError.createSQLException(SQLError.java:63) at com.mysql.cj.jdbc.result.ResultSetImpl.findColumn(ResultSetImpl.java:581) at com.mysql.cj.jdbc.result.ResultSetImpl.getLong(ResultSetImpl.java:928) at com.mchange.v2.c3p0.impl.NewProxyResultSet.getLong(NewProxyResultSet.java:2478) at org.hibernate.type.descriptor.sql.BigIntTypeDescriptor$2.doExtract(BigIntTypeDescriptor.java:73) at org.hibernate.type.descriptor.sql.BasicExtractor.extract(BasicExtractor.java:64) at org.hibernate.type.AbstractStandardBasicType.nullSafeGet(AbstractStandardBasicType.java:267) at org.hibernate.type.AbstractStandardBasicType.nullSafeGet(AbstractStandardBasicType.java:263) at org.hibernate.type.AbstractStandardBasicType.nullSafeGet(AbstractStandardBasicType.java:253) at org.hibernate.type.ManyToOneType.hydrate(ManyToOneType.java:190) at org.hibernate.persister.entity.AbstractEntityPersister.hydrate(AbstractEntityPersister.java:2969) at org.hibernate.loader.Loader.loadFromResultSet(Loader.java:1696) at org.hibernate.loader.Loader.instanceNotYetLoaded(Loader.java:1628) at org.hibernate.loader.Loader.getRow(Loader.java:1515) at org.hibernate.loader.Loader.getRowFromResultSet(Loader.java:726) at org.hibernate.loader.Loader.processResultSet(Loader.java:953) at org.hibernate.loader.Loader.doQuery(Loader.java:921) at org.hibernate.loader.Loader.doQueryAndInitializeNonLazyCollections(Loader.java:355) at org.hibernate.loader.Loader.doList(Loader.java:2554) at org.hibernate.loader.Loader.doList(Loader.java:2540) at org.hibernate.loader.Loader.listIgnoreQueryCache(Loader.java:2370) at org.hibernate.loader.Loader.list(Loader.java:2365) at org.hibernate.loader.custom.CustomLoader.list(CustomLoader.java:353) at org.hibernate.internal.SessionImpl.listCustomQuery(SessionImpl.java:1909) at org.hibernate.internal.AbstractSessionImpl.list(AbstractSessionImpl.java:311) at org.hibernate.internal.SQLQueryImpl.list(SQLQueryImpl.java:141) at com.lyn.dao.impl.TaskDaoImpl.getTaskList(TaskDaoImpl.java:74) at com.lyn.service.impl.TaskServiceImpl.getTaskList(TaskServiceImpl.java:53) at com.lyn.service.impl.TaskServiceImpl$$FastClassBySpringCGLIB$$acdada75.invoke() at org.springframework.cglib.proxy.MethodProxy.invoke(MethodProxy.java:204) at org.springframework.aop.framework.CglibAopProxy$CglibMethodInvocation.invokeJoinpoint(CglibAopProxy.java:738) at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:157) at org.springframework.transaction.interceptor.TransactionInterceptor$1.proceedWithInvocation(TransactionInterceptor.java:99) at org.springframework.transaction.interceptor.TransactionAspectSupport.invokeWithinTransaction(TransactionAspectSupport.java:282) at org.springframework.transaction.interceptor.TransactionInterceptor.invoke(TransactionInterceptor.java:96) at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:179) at org.springframework.aop.interceptor.ExposeInvocationInterceptor.invoke(ExposeInvocationInterceptor.java:92) at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:179) at org.springframework.aop.framework.CglibAopProxy$DynamicAdvisedInterceptor.intercept(CglibAopProxy.java:673) at com.lyn.service.impl.TaskServiceImpl$$EnhancerBySpringCGLIB$$7c9d87b4.getTaskList() at com.lyn.controller.PurchaserController.indexHandler(PurchaserController.java:64) at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) at java.lang.reflect.Method.invoke(Method.java:498) at org.springframework.web.method.support.InvocableHandlerMethod.doInvoke(InvocableHandlerMethod.java:205) at org.springframework.web.method.support.InvocableHandlerMethod.invokeForRequest(InvocableHandlerMethod.java:133) at org.springframework.web.servlet.mvc.method.annotation.ServletInvocableHandlerMethod.invokeAndHandle(ServletInvocableHandlerMethod.java:97) at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.invokeHandlerMethod(RequestMappingHandlerAdapter.java:827) at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.handleInternal(RequestMappingHandlerAdapter.java:738) at org.springframework.web.servlet.mvc.method.AbstractHandlerMethodAdapter.handle(AbstractHandlerMethodAdapter.java:85) at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:967) at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:901) at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:970) at org.springframework.web.servlet.FrameworkServlet.doGet(FrameworkServlet.java:861) at javax.servlet.http.HttpServlet.service(HttpServlet.java:634) at org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:846) at javax.servlet.http.HttpServlet.service(HttpServlet.java:741) at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:231) at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:53) at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) at org.springframework.web.filter.CharacterEncodingFilter.doFilterInternal(CharacterEncodingFilter.java:197) at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107) at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:199) at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:96) at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:490) at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:139) at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:92) at org.apache.catalina.valves.AbstractAccessLogValve.invoke(AbstractAccessLogValve.java:668) at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:74) at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:343) at org.apache.coyote.http11.Http11Processor.service(Http11Processor.java:408) at org.apache.coyote.AbstractProcessorLight.process(AbstractProcessorLight.java:66) at org.apache.coyote.AbstractProtocol$ConnectionHandler.process(AbstractProtocol.java:834) at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1417) at org.apache.tomcat.util.net.SocketProcessorBase.run(SocketProcessorBase.java:49) at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149) at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624) at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61) at java.lang.Thread.run(Thread.java:748)

Any help will be appericated, thanks in advance.

Stop using SQL. Use JPQL. It will load the data from all the joined tables, which your SQL does not do. — JB Nizet
@JBNizet OMG, Thanks a lot. It worked perfectly. And "loading the data from all the joined tables“ dawned on me. Thank you very much. — Saige Zhang

Saige Zhang Saige Zhang · Accepted Answer · 2019-03-31T18:13:56

The key to the solution is "not loading the data from all the joined tables" by JBNizet. Hibernate querying is object-oriented, not database-oriented, which means it selects from an "entity table" not true table from a database. Thus, in "entity table" for subclasses, it indeed has a column ptaskid. If loading the data by SQL language not JPQL or HSQL, which not joined the table, it messed up somehow. Therefore, I need to update my dao impl layer as follows:

    Session s = this.sessionFactory.getCurrentSession();
//       s.createSQLQuery("select _task.* FROM _task;")
        return (List<Task>)s.createQuery("select e FROM Task e").list();

The bug fixed.

Hibernate Joined Table strategy Polymorphism does not work due to column not found

1 Answers