Hi Paul,
FWIW, Here is a slightly edited version of my JDO query by id.
Perhaps it can help you get over this bump.
@SuppressWarnings("unchecked")
public Account lookupAccountById( PersistenceManager pm, Long accountId) {
logger.fine("looking up account id=" + accountId );
// look up
Query q1 = pm.newQuery(Account.class, "id == accountId");
q1.declareParameters("Long accountId");
List<Account> accounts = (List<Account>) q1.execute(accountId);
if (accounts == null || accounts.isEmpty()) {
logger.warning("Account Id = " + accountId + " not found.");
return null;
}
return (accounts.get(0));
}
On Fri, Oct 1, 2010 at 4:13 PM, Paul <[email protected]> wrote:
> Hi,
>
> I must admit that my db knowledge is very lacking, thus I need some
> help with making a simple query. I know I am just missing smth obvious
> and easy.
>
> Anyway, what I need is just a boolean method to check if enity
> exists.
>
> I am using Guice too, for binding all stuff.
>
> I know that the query syntax is SELECT * FROM entity WHERE __key__ =
> KEY('entity', 'key name')
>
> My class for DB queries looks like that [yeah, from gae-wicket
> template]:
>
> public abstract class JdoQueries<T>
> {
> private final Class<T> clazz;
> private final Provider<PersistenceManager> pmProvider;
>
> protected JdoQueries(Class<T> clazz, Provider<PersistenceManager>
> pmProvider)
> {
> this.clazz = clazz;
> this.pmProvider = pmProvider;
> }
>
> protected Query newQuery()
> {
> return pmProvider.get().newQuery(clazz);
> }
>
> @SuppressWarnings("unchecked")
> protected Collection<T> toCollection(Object queryResult)
> {
> return (Collection<T>) queryResult;
> }
>
> protected List<T> toList(Object queryResult)
> {
> return new ArrayList<T>(toCollection(queryResult));
> }
> }
>
>
> I know I should create public interface for query I need, then create
> a class extending JdoQueries and implementing my interface, but it's
> just theory and I cannot write that final part :)
>
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