alonp alonp - 4 months ago 39
SQL Question

Getting "org.hibernate.TransactionException: nested transactions not supported" error when deleting

When running removeUserFromConference method getting this exception:

04/06/2012 00:20:48 org.apache.catalina.core.StandardWrapperValve invoke
SEVERE: Servlet.service() for servlet [ConferenceServlet] in context with path [/conf4u] threw exception
org.hibernate.TransactionException: nested transactions not supported
at org.hibernate.engine.transaction.spi.AbstractTransactionImpl.begin(AbstractTransactionImpl.java:152)
at org.hibernate.internal.SessionImpl.beginTransaction(SessionImpl.java:1396)
at sun.reflect.GeneratedMethodAccessor39.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
at java.lang.reflect.Method.invoke(Unknown Source)
at org.hibernate.context.internal.ThreadLocalSessionContext$TransactionProtectionWrapper.invoke(ThreadLocalSessionContext.java:352)
at $Proxy12.beginTransaction(Unknown Source)
at daos.ConferenceDao.isConferenceNameExists(ConferenceDao.java:129)
at servlets.ConferenceServlet.removeUser(ConferenceServlet.java:232)
at servlets.ConferenceServlet.processRequest(ConferenceServlet.java:79)
at servlets.ConferenceServlet.doPost(ConferenceServlet.java:433)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:641)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:722)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:305)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:224)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:169)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:168)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:98)
at org.apache.catalina.valves.AccessLogValve.invoke(AccessLogValve.java:928)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:118)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:407)
at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:987)
at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:539)
at org.apache.tomcat.util.net.JIoEndpoint$SocketProcessor.run(JIoEndpoint.java:298)
at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(Unknown Source)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source)
at java.lang.Thread.run(Unknown Source)
04/06/2012 00:27:15 org.apache.catalina.core.StandardContext reload
INFO: Reloading Context with name [/conf4u] has started
04/06/2012 00:27:15 org.apache.catalina.loader.WebappClassLoader clearReferencesJdbc
SEVERE: The web application [/conf4u] registered the JDBC driver [com.mysql.jdbc.Driver] but failed to unregister it when the web application was stopped. To prevent a memory leak, the JDBC Driver has been forcibly unregistered.
04/06/2012 00:27:15 org.apache.catalina.core.StandardContext reload
INFO: Reloading Context with name [/conf4u] is completed


Dao method:

public void removeUserFromConference(Conference conference, User user) {
ConferencesUsers conferenceUser = getConferenceUser(conference, user);

Session session = HibernateUtil.getSessionFactory().getCurrentSession();
session.beginTransaction();

session.delete(conferenceUser);

session.getTransaction().commit();
}


The model class:

@Entity
@Table( name = "Conferences_Users" )
public class ConferencesUsers implements Serializable {
private static final long serialVersionUID = -3401337605668111437L;
private Conference conference;
private User user;
private int userRole;
private UserAttendanceStatus attendanceStatus;
private boolean notifiedByMail;

ConferencesUsers() {} //not public on purpose!

public ConferencesUsers(Conference conf, User user, int userRole) {
this.conference = conf;
this.user = user;
this.userRole = userRole;
this.attendanceStatus = null;
this.notifiedByMail = false;
}

public ConferencesUsers(Conference conf, User user, int userRole, UserAttendanceStatus attendanceStatus, boolean notifiedByMail) {
this.conference = conf;
this.user = user;
this.userRole = userRole;
this.attendanceStatus = attendanceStatus;
this.notifiedByMail = notifiedByMail;
}

@Id
@ManyToOne(cascade = CascadeType.ALL)
public Conference getConference() {
return conference;
}

public void setConference(Conference conference) {
this.conference = conference;
}

@Id
@ManyToOne(cascade = CascadeType.ALL)
public User getUser() {
return user;
}

public void setUser(User user) {
this.user = user;
}

@Enumerated(EnumType.STRING)
public int getUserRole() {
return userRole;
}

public void setUserRole(int userRole) {
this.userRole = userRole;
}

@Nullable
public boolean isNotifiedByMail() {
return notifiedByMail;
}

public void setNotifiedByMail(boolean notifiedByMail) {
this.notifiedByMail = notifiedByMail;
}

public UserAttendanceStatus getAttendanceStatus() {
return attendanceStatus;
}

public ConferencesUsers setAttendanceStatus(UserAttendanceStatus attendanceStatus) {
this.attendanceStatus = attendanceStatus;
return this;
}
}

Answer

You probably have begun a transaction, and trying to begin another one without having committed or rollbacked the previous one. The idiom when using programmatic transaction demarcation is the following one:

try {
    sess.getTransaction().begin();

    // do some work

    sess.getTransaction().commit()
}
catch (RuntimeException e) {
    sess.getTransaction().rollback();
    throw e;
}

This is cumbersome and error-prone, and this is one of the reasons why using EJBs or Spring to have declarative transactions is so useful.