Fix attribute refs bug when transacting tuple value (#696)

Fixes issue #695

Co-authored-by: Jonas Östlund <ostlund.jobtech@gmail.com>

src/datahike/db/transaction.cljc

@@ -591,7 +591,7 @@
 
 (defn check-tuple [db op-vec]
   (let [[_ _ a v] op-vec
-        attr-schema (-> db dbi/-schema a)]
+        attr-schema (-> db dbi/-schema (get a))]
     (cond (:db/tupleType attr-schema)
           (cond (> (count v) 8)
                 (raise "Cannot store more than 8 values for homogeneous tuple: " op-vec

test/datahike/test/attribute_refs/transact_test.cljc

@@ -189,3 +189,17 @@
       (is (= (:age e) 32))
       (is (:had-birthday e)))
     (d/release conn)))
+
+(deftest test-tuples
+  (let [conn (setup-new-connection)]
+    (d/transact conn [#:db{:ident :mapping/attributes,
+                           :valueType :db.type/tuple,
+                           :tupleTypes
+                           [:db.type/keyword :db.type/keyword :db.type/keyword],
+                           :cardinality :db.cardinality/many}])
+    (d/transact conn [{:mapping/attributes [[:mapping :mapped-id :remote-id]]}])
+    (is (= #{[[:mapping :mapped-id :remote-id]]}
+           (d/q '[:find ?v
+                  :where [?e :mapping/attributes ?v]]
+                @conn)))
+    (d/release conn)))