+ public Collection<Group> getGroupsByArtist(String artistId) throws DatabaseException {
+ Query query = new Query(Type.SELECT, "GROUPS");
+ query.addField(new Field("GROUPS.*"));
+ query.addJoin(new Join(JoinType.INNER, "GROUP_ARTISTS", new Field("GROUPS.ID"), new Field("GROUP_ARTISTS.GROUP_")));
+ query.addWhereClause(new ValueFieldWhereClause(new ValueField("GROUP_ARTISTS.ARTIST", new StringParameter(artistId))));
+ return database.getMultiple(query, groupCreator);
+ }
+
+ private class LazyArtist extends DefaultArtist {
+
+ private final Memoizer<Void> tracksMemoizer = new Memoizer<Void>(new Callable<Void>() {
+ public Void call() throws DatabaseException {
+ if (!hasValue("tracks")) {
+ value("tracks", Collection.class).set(getTracksByArtist(id()));
+ }
+ return null;
+ }
+ });
+
+ private final Memoizer<Void> groupsMemoizer = new Memoizer<Void>(new Callable<Void>() {
+
+ @Override
+ public Void call() throws Exception {
+ if (!hasValue("groups")) {
+ value("groups", Collection.class).set(getGroupsByArtist(id()));
+ }
+ return null;
+ }
+
+ });
+
+ public LazyArtist(String id) {
+ super(id);
+ }