Hi,
I am seeing the following stack trace when using HashMap in my persistable
class. I have something like this in my app.
@PersistenceCapable
public class MyClass {
...
List<ClassA> list1;
List<Class B> list2;
...
}
@PersistenceCapable
public class ClassA {
//some fields
@Persistent(serialized = "true", defaultFetchGroup = "true")
private HashMap<String, String> myMap;
@Persistent(serialized = "true", defaultFetchGroup = "true")
private List<HashMap<String, String>> myListMap;
//getters & setters
}
When I persist my MyClass object, it looks ok. I can see all List<ClassA>
being persisted correctly. I saw old post from 2 yrs ago where GAE team
member showed the example on how to persist using HashMap (like above).
When I retrieve my MyClass object with my key to update it, I see the
exception trace below. Can't we use HashMap at all? It's NOT listed in GAE
supported collection class list at
https://code.google.com/appengine/docs/java/datastore/jdo/dataclasses.html#Collections.
Any good alternatives to use? I need to use key/value pairs in that object.
Any pointers are much appreciated.
NestedThrowablesStackTrace:
java.lang.UnsupportedOperationException: FK Maps not supported.
at
org.datanucleus.store.appengine.DatastoreManager.newFKMapStore(DatastoreManager.java:589)
at
org.datanucleus.store.mapped.MappedStoreManager.getBackingStoreForMap(MappedStoreManager.java:766)
at
org.datanucleus.store.mapped.MappedStoreManager.getBackingStoreForField(MappedStoreManager.java:637)
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