DatastoreService dataSvc =...;
Query query = new Query("MessageRecipients")
.addFilter("recipients"), FilterOperator.EQUAL,userid)
.addSort("date", SortDirection.DESCENDING)
.setKeysOnly(); // <-- Only fetch keys!
//*** from the presentation , mentioned the above can only be done
using low level api, arent jdo/jpa can get the key only value as well
//***http://gae-java-persistence.blogspot.com/2009/10/keys-only-
queries.html
List<Entity> msgRecpts = dataSvc.prepare(query).asList();
List<Key> parents = new ArrayList<Key>();
for(Entity recep : msgREcpts) {
parents.add(recep.getParent());
}
//Bulk fetch parents using key list
Map<Key, Entity> msg = dataSvc.get(parents);
//***for second part above, what is the different from doing directly
"select in" statement in jpa/jdo ?
//***http://gae-java-persistence.blogspot.com/2009/12/queries-with-and-
in-filters.html
please comments...
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