public Object buscarPorId(Class o, Long id) {
		try {
			Extent e = persistencia.getExtent(o, true);
			String condicion = "id == " + id;
			Query q = persistencia.newQuery(e, condicion);
			Collection c = (Collection) q.execute();
			Iterator iter = c.iterator();
			return c.toArray()[0];
		} catch (Exception e) {
			return null;
		}
	}