Hello,
Read
http://code.google.com/appengine/docs/java/datastore/dataclasses.html#Object_Fields_and_Entity_Properties
one possibility that 1 see: a change of type / format that you made to
some prop of your object and you access old entities in the datastore
with the new code. This may generate such an exception if DS cannot
convert old format to new one.
didier
On Sep 30, 1:16 am, "hendrix.jason" <hendrix.ja...@gmail.com> wrote:
> What could this error mean:
>
> java.lang.ClassCastException:
> [Lcom.google.appengine.api.datastore.Key; cannot be cast to
> com.google.appengine.api.datastore.Key
>
> It's happening on the last line of this code:
>
> PersistenceManager pm2 = PMF.get().getPersistenceManager();
> Key k =
> KeyFactory.createKey(User.class.getSimpleName(),Long.parseLong(Key));
> User u = pm2.getObjectById(User.class, k);
>
> Long[] group_array = u.getGroups();
> Key[] group_keys = new Key[group_array.length];
> int c = 0;
> while(c < group_array.length){
> group_keys[c] =
> KeyFactory.createKey(Group.class.getSimpleName(),
> group_array[c]);
> c++;
> }
>
> javax.jdo.Query q =
> pm2.newQuery(Group.class,"key.contains(:key)");
> List<Group> groups = (List<Group>) q.execute(group_keys);
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