HEllo everybody, I'm facing an issue with JDO which is presented elsewhere in the group, but with no workaround.
I simply need to retrieve an object from JDO using only the key. That is do something like this PersistenceManager pm = pmf.getPersistenceManager(); SimpleObject ll = new SimpleObject; try{ pm.makePersistent(ll); Key leftKey = ll.getKey(); Object retriveved = pm.getObjectById(leftKey); } finally{ pm.close(); } This does not work. Documentation at http://code.google.com/appengine/docs/java/datastore/creatinggettinganddeletingdata.html#Getting_an_Object_By_Key states you must provide a class identifier to retrieve objects using keys, so call SimpleObject retriveved = pm.getObjectById(SimpleObject.class, leftKey); And that works, indeed. The point is in the real application. I need to retrieve objects without knowing the class, then treat them differently according to their type. Actually I must model something similar to a tree (which is not possible to do without using key references due to the way keys are generated). I need to save the keys for left and right child of the tree, then retrieve the objects and treat inner nodes differently from leafs. Are there workarounds to get an object using its key in JDO? Maybe I should use low-level API to detect the kind of the entity. Thanks for any advice Lorenzo -- You received this message because you are subscribed to the Google Groups "Google App Engine for Java" group. To post to this group, send email to google-appengine-j...@googlegroups.com. To unsubscribe from this group, send email to google-appengine-java+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/google-appengine-java?hl=en.