Hibernate version: 3.2.1 - Annotations 3.2

I have two entities Parent and Child. The parent holds an indexed list of Children, and I'm pretty sure I'm doing this right. I can save the relationship, and update the index, but I'm not able to add a Child to the List after it is saved.

Since I'm getting the database object in one session and updating it in another, I'm using the merge command to persist the updated object.

session.merge(parent)

I get an exception on the added child id which hibernate sets to DelayedPostIdentifier.

The session is opened and closed per request, and the web application does something like this:

Session 1: get Parent and initialize the Child collection
...
Session 5: add new Child to List
...
Session 7: merge parent to persist it to database.
exception

Is this a problem with the merge() function, or am I doing something wrong?

Full stack trace of any exception that occurs:

org.hibernate.TypeMismatchException: Provided id of the wrong type. Expected: class java.lang.Long, got class org.hibernate.action.DelayedPostInsertIdentifier
at org.hibernate.event.def.DefaultLoadEventListener.onLoad(DefaultLoadEventListener.java:86)
at org.hibernate.impl.SessionImpl.fireLoad(SessionImpl.java:878)
at org.hibernate.impl.SessionImpl.internalLoad(SessionImpl.java:846)
at org.hibernate.type.EntityType.resolveIdentifier(EntityType.java:557)
at org.hibernate.type.EntityType.resolve(EntityType.java:379)
at org.hibernate.type.EntityType.replace(EntityType.java:259)
at org.hibernate.type.CollectionType.replaceElements(CollectionType.java:425)
at org.hibernate.type.CollectionType.replace(CollectionType.java:487)
at org.hibernate.type.TypeFactory.replace(TypeFactory.java:462)
at org.hibernate.event.def.DefaultMergeEventListener.copyValues(DefaultMergeEventListener.java:340)
at org.hibernate.event.def.DefaultMergeEventListener.entityIsPersistent(DefaultMergeEventListener.java:153)
at org.hibernate.event.def.DefaultMergeEventListener.onMerge(DefaultMergeEventListener.java:126)
at org.hibernate.event.def.DefaultMergeEventListener.onMerge(DefaultMergeEventListener.java:53)
at org.hibernate.impl.SessionImpl.fireMerge(SessionImpl.java:677)
at org.hibernate.impl.SessionImpl.merge(SessionImpl.java:661)
at org.hibernate.impl.SessionImpl.merge(SessionImpl.java:665)
at org.product.data.handlers.GenericInstanceHandler.mergeInstance(GenericInstanceHandler.java:50)
at org.product.web.EditForm.save(EditForm.java:233)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
at java.lang.reflect.Method.invoke(Unknown Source)
at com.sun.el.parser.AstValue.invoke(AstValue.java:151)
at com.sun.el.MethodExpressionImpl.invoke(MethodExpressionImpl.java:283)
at com.sun.facelets.el.TagMethodExpression.invoke(TagMethodExpression.java:68)
at com.sun.facelets.el.LegacyMethodBinding.invoke(LegacyMethodBinding.java:69)
at org.apache.myfaces.application.ActionListenerImpl.processAction(ActionListenerImpl.java:63)
at javax.faces.component.UICommand.broadcast(UICommand.java:106)
at org.ajax4jsf.framework.ajax.AjaxViewRoot.processEvents(AjaxViewRoot.java:274)
at org.ajax4jsf.framework.ajax.AjaxViewRoot.broadcastEvents(AjaxViewRoot.java:250)
at org.ajax4jsf.framework.ajax.AjaxViewRoot.processApplication(AjaxViewRoot.java:405)
at org.apache.myfaces.lifecycle.LifecycleImpl.invokeApplication(LifecycleImpl.java:343)
at org.apache.myfaces.lifecycle.LifecycleImpl.execute(LifecycleImpl.java:86)
at javax.faces.webapp.FacesServlet.service(FacesServlet.java:137)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:252)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:173)
at org.ajax4jsf.framework.ajax.xmlfilter.BaseXMLFilter.doXmlFilter(BaseXMLFilter.java:67)
at org.ajax4jsf.framework.ajax.xmlfilter.BaseFilter.doFilter(BaseFilter.java:223)
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.ApplicationDispatcher.invoke(ApplicationDispatcher.java:672)
at org.apache.catalina.core.ApplicationDispatcher.processRequest(ApplicationDispatcher.java:463)
at org.apache.catalina.core.ApplicationDispatcher.doForward(ApplicationDispatcher.java:398)
at org.apache.catalina.core.ApplicationDispatcher.forward(ApplicationDispatcher.java:301)
at org.tuckey.web.filters.urlrewrite.NormalRewrittenUrl.doRewrite(NormalRewrittenUrl.java:183)
at org.tuckey.web.filters.urlrewrite.RuleChain.handleRewrite(RuleChain.java:125)
at org.tuckey.web.filters.urlrewrite.RuleChain.doRules(RuleChain.java:107)
at org.tuckey.web.filters.urlrewrite.UrlRewriter.processRequest(UrlRewriter.java:78)
at org.tuckey.web.filters.urlrewrite.UrlRewriteFilter.doFilter(UrlRewriteFilter.java:383)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:202)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:173)
at org.apache.myfaces.webapp.filter.ExtensionsFilter.doFilter(ExtensionsFilter.java:144)
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.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:869)
at org.apache.coyote.http11.Http11BaseProtocol$Http11ConnectionHandler.processConnection(Http11BaseProtocol.java:664)
at org.apache.tomcat.util.net.PoolTcpEndpoint.processSocket(PoolTcpEndpoint.java:527)
at org.apache.tomcat.util.net.LeaderFollowerWorkerThread.runIt(LeaderFollowerWorkerThread.java:80)
at org.apache.tomcat.util.threads.ThreadPool$ControlRunnable.run(ThreadPool.java:684)
at java.lang.Thread.run(Unknown Source)

Name and version of the database you are using:

MySQL 5.0.21

Please post mapping, POJOs and session/transaction code