App-Engine throws NullPointerException on getByObjectId call of an entity that has been updated

Question

I am using google datastore to persist data as objects of a model class- 'zone' . This model has been updated with more parameters recently. When I deployed the new code, get calls on the existing 'zone' entities is resulting in an error. Existing zone entities do not have the newly added parameter(Marked in the zone class).

ERROR: Error in Service {}  at com.tryout.cdapp.exceptions.handler.CNDApplicationExceptionHandler.(CNDApplicationExceptionHandler.java:30) on 2014-10-14 03:21:48,002
java.lang.NullPointerException
    at com.google.appengine.datanucleus.scostore.FKListStore.getIndexPropertyName(FKListStore.java:965)
    at com.google.appengine.datanucleus.scostore.FKListStore.getFilterPredicates(FKListStore.java:940)
    at com.google.appengine.datanucleus.scostore.FKListStore.listIterator(FKListStore.java:383)
    at com.google.appengine.datanucleus.scostore.FKListStore.listIterator(FKListStore.java:349)
    at com.google.appengine.datanucleus.scostore.FKListStore.iterator(FKListStore.java:342)
    at org.datanucleus.store.types.sco.backed.List.loadFromStore(List.java:304)
    at org.datanucleus.store.types.sco.backed.List.initialise(List.java:253)
    at org.datanucleus.store.types.sco.SCOUtils.createSCOWrapper(SCOUtils.java:253)
    at org.datanucleus.store.types.sco.SCOUtils.newSCOInstance(SCOUtils.java:139)
    at org.datanucleus.store.mapped.mapping.AbstractContainerMapping.replaceFieldWithWrapper(AbstractContainerMapping.java:396)
    at org.datanucleus.store.mapped.mapping.AbstractContainerMapping.postFetch(AbstractContainerMapping.java:414)
    at com.google.appengine.datanucleus.DatastorePersistenceHandler.fetchObject(DatastorePersistenceHandler.java:599)
    at org.datanucleus.state.JDOStateManager.loadFieldsFromDatastore(JDOStateManager.java:1638)
    at org.datanucleus.state.JDOStateManager.validate(JDOStateManager.java:3511)
    at org.datanucleus.ObjectManagerImpl.findObject(ObjectManagerImpl.java:3379)
    at org.datanucleus.api.jdo.JDOPersistenceManager.getObjectById(JDOPersistenceManager.java:1722)
    at org.datanucleus.api.jdo.JDOPersistenceManager.getObjectById(JDOPersistenceManager.java:1740)
    at com.tryout.cdapp.dao.impl.BaseDaoImpl.findById(BaseDaoImpl.java:103)
    at com.tryout.cdapp.service.impl.ZoneServiceImpl.getZoneById(ZoneServiceImpl.java:55)
    at com.tryout.cdapp.resource.ZoneResource.getById(ZoneResource.java:75)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:45)
    at org.jboss.resteasy.core.MethodInjectorImpl.invoke(MethodInjectorImpl.java:137)
    at org.jboss.resteasy.core.ResourceMethodInvoker.invokeOnTarget(ResourceMethodInvoker.java:280)
    at org.jboss.resteasy.core.ResourceMethodInvoker.invoke(ResourceMethodInvoker.java:234)
    at org.jboss.resteasy.core.ResourceMethodInvoker.invoke(ResourceMethodInvoker.java:221)
    at org.jboss.resteasy.core.SynchronousDispatcher.invoke(SynchronousDispatcher.java:356)
    at org.jboss.resteasy.core.SynchronousDispatcher.invoke(SynchronousDispatcher.java:179)
    at org.jboss.resteasy.plugins.server.servlet.ServletContainerDispatcher.service(ServletContainerDispatcher.java:220)
    at org.jboss.resteasy.plugins.server.servlet.HttpServletDispatcher.service(HttpServletDispatcher.java:56)
    at org.jboss.resteasy.plugins.server.servlet.HttpServletDispatcher.service(HttpServletDispatcher.java:51)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:717)
    at org.mortbay.jetty.servlet.ServletHolder.handle(ServletHolder.java:511)
    at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1166)
    at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1157)
    at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1157)
    at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1157)
    at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1157)
    at org.mortbay.jetty.servlet.ServletHandler.handle(ServletHandler.java:388)
    at org.mortbay.jetty.security.SecurityHandler.handle(SecurityHandler.java:216)
    at org.mortbay.jetty.servlet.SessionHandler.handle(SessionHandler.java:182)
    at org.mortbay.jetty.handler.ContextHandler.handle(ContextHandler.java:765)
    at org.mortbay.jetty.webapp.WebAppContext.handle(WebAppContext.java:418)
    at org.mortbay.jetty.handler.HandlerWrapper.handle(HandlerWrapper.java:152)
    at org.mortbay.jetty.Server.handle(Server.java:326)
    at org.mortbay.jetty.HttpConnection.handleRequest(HttpConnection.java:542)
    at org.mortbay.jetty.HttpConnection$RequestHandler.headerComplete(HttpConnection.java:923)
    at org.mortbay.jetty.HttpConnection.handle(HttpConnection.java:404)
    at com.google.tracing.TraceContext$TraceContextRunnable.runInContext(TraceContext.java:438)
    at com.google.tracing.TraceContext$TraceContextRunnable$1.run(TraceContext.java:445)
    at com.google.tracing.CurrentContext.runInContext(CurrentContext.java:220)
    at com.google.tracing.TraceContext$AbstractTraceContextCallback.runInInheritedContextNoUnref(TraceContext.java:309)
    at com.google.tracing.TraceContext$AbstractTraceContextCallback.runInInheritedContext(TraceContext.java:301)
    at com.google.tracing.TraceContext$TraceContextRunnable.run(TraceContext.java:442)
    at java.lang.Thread.run(Thread.java:724)

This is the code in the Dao -

private final Class<T> persistentClass;
    public BaseDaoImpl() {
            persistentClass = (Class<T>) ((ParameterizedType) getClass().getGenericSuperclass()).getActualTypeArguments()[0];
        }
        public T findById(Serializable id) {

                    PersistenceManager pm = PMF.get().getPersistenceManager();

                    try {
                        T t = pm.getObjectById(persistentClass, id);
                        t.toString();
                        return t;

                    } finally {

                        pm.close();

                    }
                }

This is the code in service -

 public Zone getZoneById(String id) {
        Zone zone = zoneDao.findById(id);
        return zone;
    }

This is model class - 'Zone'

public class Zone implements Serializable {

    private static final long serialVersionUID = 3946928960755099560L;
    @PrimaryKey
    @Persistent(valueStrategy = IdGeneratorStrategy.IDENTITY)
    @Extension(vendorName = "datanucleus", key = "gae.encoded-pk", value = "true")
    private String id;
    @Persistent
    private String name;
    @Persistent
    private String siteId;
    @Persistent
    private String orgId;
    @Persistent(defaultFetchGroup = "true")
    private List<LocationCoordinates> locationCoordinates;
    @Persistent
    private Date created;
    @Persistent
    private String description;
    @Persistent
    private String urlExtension;
    @Persistent
    private Integer timeSpentThreshold;
    @Persistent
    private Double tuningNumber;
    @Persistent(defaultFetchGroup = "true")
    private HashMap<String, String> zonePayload;
    @Persistent(defaultFetchGroup = "true")
    private List<ZoneSignalValue> zoneSignalValueList;  //Newly Added

    //Getters and Setters
}

How can I resolve this? Thanks in advance.

Answer 1

You need to update the existing entities. You can refer this doc. https://cloud.google.com/appengine/articles/update_schema