Are tuples supported in the Java API?

Peer API
1

Hi All,

I’m trying to learn how tuple schema types ( :db.type/tuple) are handled in the Java API. I see no mention of it anywhere. Can someone please point me in the right direction?

Thanks!
Joe

2

Nothing special in Java, API wise. Tuples are just Lists

The example from the docs works just fine:

public class TupleDemo {

    @Rule
    public final DatomicTestDb datomic = new DatomicTestDb("tupleDemo");

    @Test
    public void tuplesWorkWithJava() throws ExecutionException, InterruptedException {
        datomic.connection().transact(Util.list(
                Util.map(":db/ident", ":player/location",
                        ":db/valueType", ":db.type/tuple",
                        ":db/tupleTypes", Util.read("[ :db.type/long :db.type/long]"),
                        ":db/cardinality", ":db.cardinality/one")

        )).get();

        Map txResult = datomic.connection().transact(Util.list(Util.list(":db/add", "newPlayer", ":player/location", Util.list(100L, 50L)))).get();

        Database db = (Database) txResult.get(Connection.DB_AFTER);
        Object newPlayerE = Peer.resolveTempid(
                db,
                txResult.get(Connection.TEMPIDS),
                "newPlayer"
        );

        Object locationTuple = Peer.query("[:find ?location . :where [?player :player/location ?location] :in $ ?player]", db, newPlayerE);

        assertThat(locationTuple).isInstanceOf(List.class);
        assertThat((List)locationTuple).hasSize(2);
        assertThat((List)locationTuple).containsExactly(100L, 50L);

    }

}

(If you want to run this, the @Rule above is just a test harness helper I have for crating mem dbs for testing, assertions provided by assertj)

3

Ahhh. I must have missed that example in the docs. This should get me started. Thanks Adam!

4

Well, maybe you didn’t, the docs example is written in clojure, so I just adapted from that for my post: https://docs.datomic.com/on-prem/schema.html#heterogeneous-tuples

Anyway, tuples don’t really add any new data types on the API side, just schema.

5

OK, well that would explain it. I would, at the very least, have expected there to be a TYPE_TUPLE constant in the Attribute class. But there are no mentions of tuples anywhere at all that I can see! The Java API could use a spruce-up, but I’m good on my end thanks to the code snippet you gave me.

Thanks again!