private Instrument getInstrument(String instrument) {
Query q = em.createQuery("select i from Instrument i where i.nom='" + instrument + "'");
List results = q.getResultList();
if (!results.isEmpty()) {
Iterator stIterator = results.iterator();
Instrument a = (Instrument) stIterator.next();
return a;
} else {
Instrument i = new Instrument(instrument);
em.persist(i);
return i;
}
}