JDO - HashMap inside an inline class

Question

Can I save a HashMap in a built-in class in App Engine? I have the following class:

@Persistent(serialized = "true")
@Embedded
private Stats stats;

@PersistenceCapable
@EmbeddedOnly
public static class Stats implements Serializable {
    private static final long serialVersionUID = 1L;        
    @Persistent(serialized = "true", defaultFetchGroup="true")
    private Map<String, Integer> requests;

    public Stats() {
        requests = new HashMap<String, Integer>();
    }
}

However, when I try to add an item to the HashMap and save it, I get the following error:

The specified class class com.google.appengine.api.datastore.Blob is not sustainable

I know that you can successfully use HashMap in a “normal” class, but can they also be used in an inline class?

thank

Answer 1

I did not try it with the Embedded class, but my Maps inside JDO objects needed additional FetchGroup annotations in the containing class ...

    @SuppressWarnings("serial

        ")
        @PersistenceCapable(identityType=IdentityType.APPLICATION, detachable="true")
        @FetchGroup(name="QueryAggregationJobJDO", members={
                                                @Persistent(name="appName", recursionDepth=-1),
etc....                                         
        public class QueryAggregationJobJDO extends AggregationJobJDO implements SystemObject {
            @Persistent(serialized="true")  // this is string of app names and a count for each name found
            public Map< String, Long >  appName = new HashMap<String, Long>();

getFetchPlan() DataManager...

@Override
public boolean open() {
    DataAreaManager dataAreaManager = new DataAreaManager();
    dataAreaManager.setDataArea(VERSION_DATA_AREA);

    if ((pm == null) || (pm.isClosed())) {

        pm = PMF.get(type).getPersistenceManager();
        pm.getFetchPlan().addGroup("TouchActiveUserJDO");
        pm.getFetchPlan().addGroup("UserRoleJDO");
        pm.getFetchPlan().addGroup("QueryAggregationJobJDO");