Hi,
I have following object child relationship. All the objects are getting
saved properly but when I try to fetch child object I am getting
NullPointerException. This error is not because of lazy loading as I am
accessing the child before closing the PersistentManager. Aren't interfaces
fully supported by JOD?
============ Parent Object Class ==============
@PersistenceCapable(identityType = IdentityType.APPLICATION)
public class Block implements Serializable {
@PrimaryKey
@Persistent(valueStrategy = IdGeneratorStrategy.IDENTITY)
private Long block_id;
@Persistent(defaultFetchGroup = "true")
private BlockModule block_module;
....
....
============= Child Interface and Implementation ============
public interface BlockModule extends Serializable{
String getTitle(HttpServletRequest req);
String getContent(HttpServletRequest req);
}
@PersistenceCapable(identityType = IdentityType.APPLICATION)
public class BlockTextHTML implements BlockModule{
@PrimaryKey
@Persistent(valueStrategy = IdGeneratorStrategy.IDENTITY)
protected Key key;
@Persistent
private String block_title;
@Persistent(types = {BlockTextHTML.class})
private String block_content;
....
....
================= ERROR LOG ================
Uncaught exception from servlet
java.lang.NullPointerException
at
org.datanucleus.store.mapped.identifier.JPOXIdentifierFactory.newDatastoreContainerIdentifier(JPOXIdentifierFactory.java:258)
at
org.datanucleus.store.appengine.DatastoreRelationFieldManager.lookupOneToOneChild(DatastoreRelationFieldManager.java:316)
at
org.datanucleus.store.appengine.DatastoreRelationFieldManager.fetchRelationField(DatastoreRelationFieldManager.java:286)
at
org.datanucleus.store.appengine.DatastoreFieldManager.fetchObjectField(DatastoreFieldManager.java:271)
at
org.datanucleus.state.AbstractStateManager.replacingObjectField(AbstractStateManager.java:1197)
at antshpra.Block.jdoReplaceField(Block.java)
at antshpra.Block.jdoReplaceFields(Block.java)
at
org.datanucleus.state.JDOStateManagerImpl.replaceFields(JDOStateManagerImpl.java:2772)
at
org.datanucleus.state.JDOStateManagerImpl.replaceFields(JDOStateManagerImpl.java:2791)
at
org.datanucleus.store.appengine.DatastorePersistenceHandler.fetchObject(DatastorePersistenceHandler.java:443)
at
org.datanucleus.state.JDOStateManagerImpl.loadSpecifiedFields(JDOStateManagerImpl.java:1519)
at
org.datanucleus.state.JDOStateManagerImpl.isLoaded(JDOStateManagerImpl.java:1925)
at antshpra.Block.jdoGetModule(Block.java)
at antshpra.Block.getModule(Block.java:77)
at antshpra.servlets.InitializeDemo.doRequest(InitializeDemo.java:28)
at antshpra.Main.doGet(Main.java:76)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:693)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:806)
at
org.mortbay.jetty.servlet.ServletHolder.handle(ServletHolder.java:487)
at
org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1093)
at
com.google.apphosting.runtime.jetty.SaveSessionFilter.doFilter(SaveSessionFilter.java:35)
at
org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1084)
at
com.google.apphosting.utils.servlet.TransactionCleanupFilter.doFilter(TransactionCleanupFilter.java:43)
at
org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1084)
at
org.mortbay.jetty.servlet.ServletHandler.handle(ServletHandler.java:360)
at
org.mortbay.jetty.security.SecurityHandler.handle(SecurityHandler.java:216)
at
org.mortbay.jetty.servlet.SessionHandler.handle(SessionHandler.java:181)
at
org.mortbay.jetty.handler.ContextHandler.handle(ContextHandler.java:712)
at org.mortbay.jetty.webapp.WebAppContext.handle(WebAppContext.java:405)
at
com.google.apphosting.runtime.jetty.AppVersionHandlerMap.handle(AppVersionHandlerMap.java:237)
at
org.mortbay.jetty.handler.HandlerWrapper.handle(HandlerWrapper.java:139)
at org.mortbay.jetty.Server.handle(Server.java:313)
at
org.mortbay.jetty.HttpConnection.handleRequest(HttpConnection.java:506)
at
org.mortbay.jetty.HttpConnection$RequestHandler.headerComplete(HttpConnection.java:830)
at
com.google.apphosting.runtime.jetty.RpcRequestParser.parseAvailable(RpcRequestParser.java:76)
at org.mortbay.jetty.HttpConnection.handle(HttpConnection.java:381)
at
com.google.apphosting.runtime.jetty.JettyServletEngineAdapter.serviceRequest(JettyServletEngineAdapter.java:139)
at
com.google.apphosting.runtime.JavaRuntime.handleRequest(JavaRuntime.java:235)
at
com.google.apphosting.base.RuntimePb$EvaluationRuntime$6.handleBlockingRequest(RuntimePb.java:4950)
at
com.google.apphosting.base.RuntimePb$EvaluationRuntime$6.handleBlockingRequest(RuntimePb.java:4948)
at
com.google.net.rpc.impl.BlockingApplicationHandler.handleRequest(BlockingApplicationHandler.java:24)
at com.google.net.rpc.impl.RpcUtil.runRpcInApplication(RpcUtil.java:359)
at com.google.net.rpc.impl.Server$2.run(Server.java:823)
at
com.google.tracing.LocalTraceSpanRunnable.run(LocalTraceSpanRunnable.java:56)
at
com.google.tracing.LocalTraceSpanBuilder.internalContinueSpan(LocalTraceSpanBuilder.java:516)
at com.google.net.rpc.impl.Server.startRpc(Server.java:778)
at com.google.net.rpc.impl.Server.processRequest(Server.java:351)
at
com.google.net.rpc.impl.ServerConnection.messageReceived(ServerConnection.java:437)
at
com.google.net.rpc.impl.RpcConnection.parseMessages(RpcConnection.java:319)
at
com.google.net.rpc.impl.RpcConnection.dataReceived(RpcConnection.java:290)
at com.google.net.async.Connection.handleReadEvent(Connection.java:428)
at
com.google.net.async.EventDispatcher.processNetworkEvents(EventDispatcher.java:762)
at
com.google.net.async.EventDispatcher.internalLoop(EventDispatcher.java:207)
at com.google.net.async.EventDispatcher.loop(EventDispatcher.java:101)
at
com.google.net.rpc.RpcService.runUntilServerShutdown(RpcService.java:251)
at
com.google.apphosting.runtime.JavaRuntime$RpcRunnable.run(JavaRuntime.java:392)
at java.lang.Thread.run(Unknown Source)
Unexpected exception from servlet: java.lang.NullPointerException
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