Iterating & casting after query

monkeyden · **Joined:** Wed Jun 07, 2006 12:28 pm **Posts:** 22

Hibernate 3.1 beta 3
JBoss 4.0.3

I am having trouble while iterating over a List of results. I get a ClassCastException when I try to cast the proxy to User. Type found in the collection is com.monkeyden.pipeline.poc.bo.User$$EnhancerByCGLIB$$646a18c4

Code:

Query query = session.createQuery("from com.monkeyden.pipeline.poc.bo.User u where " +
                    "lower(u.email) like lower(:email)");
Iterator users = query.iterate();
while(users.hasNext()){
    Object current = users.next();
    User current = (User)current;
    results.add(current);
}

Code:

<class name="com.monkeyden.pipeline.poc.bo.User" table="USERS">
    <id name="id" type="java.lang.Long">
        <column name="USER_ID" not-null="true" sql-type="NUMBER" />
        <generator class="native">
            <!--  
                To add non XDoclet generator parameters, create a file named 
                hibernate-generator-params-User.xml 
                containing the additional parameters and place it in your merge dir. 
            -->
        </generator>
    </id>
    <property name="createDate" type="java.util.Date" update="true" insert="true">
        <column name="CREATE_DATE" not-null="true" sql-type="DATE" />
    </property>
    <property name="displayName" type="java.lang.String" update="true" insert="true">
        <column name="DISPLAY_NAME" not-null="true" sql-type="VARCHAR2" />
    </property>
    <property name="email" type="java.lang.String" update="true" insert="true">
        <column name="EMAIL" not-null="true" sql-type="VARCHAR2" />
    </property>
    <property name="password" type="java.lang.String" update="true" insert="true">
        <column name="PASSWORD" not-null="true" sql-type="VARCHAR2" />
    </property>
    <property name="username" type="java.lang.String" update="true" insert="true">
        <column name="USERNAME" not-null="true" sql-type="VARCHAR2" />
    </property>
</class>

szroland · **Joined:** Sat Jun 03, 2006 6:23 pm **Posts:** 28

The proxy is an actual subclass of your class, which means you should be able to cast it.

Are you sure, though, that the code you posted is the code that is run?

You cannot redefine a variable in the same context, so this should not compile:

while(users.hasNext()){
Object current = users.next();
User current = (User)current;
results.add(current);
}

Roland

monkeyden · **Joined:** Wed Jun 07, 2006 12:28 pm **Posts:** 22

szroland wrote:

The proxy is an actual subclass of your class, which means you should be able to cast it.

Are you sure, though, that the code you posted is the code that is run?

You cannot redefine a variable in the same context, so this should not compile:

while(users.hasNext()){
Object current = users.next();
User current = (User)current;
results.add(current);
}

Roland

Sorry, copy and paste flub. Here is the actual code:

Code:

Query query = session.createQuery("from com.monkeyden.pipeline.poc.bo.User u where " +
                    "lower(u.email) like lower(:email)");

query.setParameter("email", email);

Iterator users = query.iterate();
while(users.hasNext()){
    Object row = users.next();
    User current = (User)row;
    results.add(current);
}

szroland · **Joined:** Sat Jun 03, 2006 6:23 pm **Posts:** 28

Could you add these four lines, and show the result, including the exception itself?

while(users.hasNext()){
Object row = users.next();
System.out.println(row.getClass());
System.out.println(row.getClass().getGenericSuperclass());
System.out.println(User.class);
System.out.println(row instanceof User);

User current = (User)row;
results.add(current);
}

monkeyden · **Joined:** Wed Jun 07, 2006 12:28 pm **Posts:** 22

The output was:

class com.nemoves.pipeline.poc.bo.User$$EnhancerByCGLIB$$71e1d5b6
class com.nemoves.pipeline.poc.bo.User
false

This has as much information as any RuntimeException, so I figured it wasn't worth putting in the initial post. Thanks

Code:

java.lang.ClassCastException
at com.monkeyden.pipeline.action.SimpleSearchAction.doSubmit(SimpleSearchAction.java:80)
at com.monkeyden.pipeline.admin.PipelineRequestProcessor.processActionPerform(PipelineRequestProcessor.java:49)
at org.apache.struts.action.RequestProcessor.process(RequestProcessor.java:236)
at org.apache.struts.action.ActionServlet.process(ActionServlet.java:1196)
at org.apache.struts.action.ActionServlet.doPost(ActionServlet.java:432)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:717)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:810)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:252)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:173)
at com.monkeyden.pipeline.servlets.HibernateFilter.doFilter(HibernateFilter.java:55)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:202)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:173)
at org.jboss.web.tomcat.filters.ReplyHeaderFilter.doFilter(ReplyHeaderFilter.java:81)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:202)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:173)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:213)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:178)
at org.jboss.web.tomcat.security.CustomPrincipalValve.invoke(CustomPrincipalValve.java:39)
at org.jboss.web.tomcat.security.SecurityAssociationValve.invoke(SecurityAssociationValve.java:159)
at org.jboss.web.tomcat.security.JaccContextValve.invoke(JaccContextValve.java:59)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:126)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:105)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:107)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:148)
at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:856)
at org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.processConnection(Http11Protocol.java:744)
at org.apache.tomcat.util.net.PoolTcpEndpoint.processSocket(PoolTcpEndpoint.java:527)
at org.apache.tomcat.util.net.MasterSlaveWorkerThread.run(MasterSlaveWorkerThread.java:112)
at java.lang.Thread.run(Thread.java:534)

tenwit · **Joined:** Thu Dec 23, 2004 9:08 pm **Posts:** 2008

Is User a final class, or does it contain any final methods or members? If it does, remove all instances of the "final" keyword and try it again..

szroland · **Joined:** Sat Jun 03, 2006 6:23 pm **Posts:** 28

monkeyden wrote:

The output was:
class com.nemoves.pipeline.poc.bo.User$$EnhancerByCGLIB$$71e1d5b6
class com.nemoves.pipeline.poc.bo.User
false

Why was the ouput only 3 lines, instead of 4?

My last idea is that the User class you imported in your SimpleSearchAction class, is not com.nemoves.pipeline.poc.bo.User but from some other package. Now you only have 3 lines of output, so I don't know if com.nemoves.pipeline.poc.bo.User is the ancestor class of the proxy (which it should be), or the actually imported User class you are trying to cast to (User.class).

Roland

hibernate_user · **Joined:** Mon May 22, 2006 2:30 pm **Posts:** 74

You didn't somehow import a different class named "User" from a different package by accident, or anything like that? That would cause the same problem. I know it's a long shot.

monkeyden · **Joined:** Wed Jun 07, 2006 12:28 pm **Posts:** 22

The class is public and has a public no-arg and doesn't have any final data members. Is there anything I can check in the proxy instance that will shed some light on this? I can dig around in the debugger. I didn't see anything that stood out.

monkeyden · **Joined:** Wed Jun 07, 2006 12:28 pm **Posts:** 22

Quote:

Why was the ouput only 3 lines, instead of 4?

Because getGenericSuperclass() is undefined for type class.

EDIT: Just realized it's available in Java 5. I'm using java 1.4

Quote:

My last idea is that the User class you imported in your SimpleSearchAction class, is not com.nemoves.pipeline.poc.bo.User but from some other package. Now you only have 3 lines of output, so I don't know if com.nemoves.pipeline.poc.bo.User is the ancestor class of the proxy (which it should be), or the actually imported User class you are trying to cast to (User.class).

You'll notice that in previous messages in this thread it has com.monkeyden for the package, which was an obfuscation attempt I grew tired of, but I assure you they are both in com.nemoves.pipeline.poc.bo. That was one of the first things I checked, since we have several projects with a User class. This is proven by the system output.

tenwit · **Joined:** Thu Dec 23, 2004 9:08 pm **Posts:** 2008

If you want to verify that the proxy class is extending the correct User, you could use code like this:

Code:

while (users.hasNext()) {
  Object row = users.next();
  int i = 0;
  for (Object o = row; o.getClass() != Object.class; o = o.getSuperclass())
  {
    System.out.println("Ancestor " + i++ + " has class " + o.getClass().getName());
  }

  User current = (User)row;
  results.add(current);
}

Obviously, "Ancestor 0" will be the class itself.

szroland · **Joined:** Sat Jun 03, 2006 6:23 pm **Posts:** 28

monkeyden wrote:

Quote:

Why was the ouput only 3 lines, instead of 4?

Because getGenericSuperclass() is undefined for type class.

Yes, sorry, that'd JDK 5. You could try getSuperclass() instead.

Otherwise, I'm really out of ideas. The proxy should be a subclass, I see no reason why it is not so (except your class being final, but that should generate an error early on I think). Sorry I couldn't help.

monkeyden · **Joined:** Wed Jun 07, 2006 12:28 pm **Posts:** 22

Object.getSuperclass() is also not available.

szroland · **Joined:** Sat Jun 03, 2006 6:23 pm **Posts:** 28

monkeyden wrote:

Object.getSuperclass() is also not available.

It's a method of Class. So you would go like this: object.getClass().getSuperclass().

Or:
for (Class o = row.getClass(); o != Object.class; o = o.getSuperclass()) {
System.out.println(o);
}

monkeyden · **Joined:** Wed Jun 07, 2006 12:28 pm **Posts:** 22

I know JDO has a detachable attribute for the class. Does Hibernate have such an attribute? I didnt see anything related in the DTD.

Thanks for the sustained effort.