Fixed empty non-queried relation not affecting results (closes #385)

Author: tonsky

CHANGELOG.md

@@ -1,3 +1,7 @@
+# WIP
+
+- Fixed empty non-queried relation not affecting results #385
+
 # 1.0.4
 
 - Implement nav/datafy for entities #325 thx @IamDrowsy

script/watch.sh

@@ -2,4 +2,4 @@
 
 cd "`dirname $0`/.."
 
-clojure -A:test -m kaocha.runner --watch "$@"
+clojure -A:test -M -m kaocha.runner --watch "$@"

src/datascript/query.cljc

@@ -861,23 +861,33 @@
     (let [rels (:rels context)]
       (-collect [(da/make-array (count symbols))] rels symbols)))
   ([acc rels symbols]
-    (if-some [rel (first rels)]
-      (let [keep-attrs (select-keys (:attrs rel) symbols)]
-        (if (empty? keep-attrs)
-          (recur acc (next rels) symbols)
-          (let [copy-map (to-array (map #(get keep-attrs %) symbols))
-                len      (count symbols)]
-            (recur (for [#?(:cljs t1
-                            :clj ^{:tag "[[Ljava.lang.Object;"} t1) acc
-                         t2 (:tuples rel)]
-                     (let [res (aclone t1)]
-                       (dotimes [i len]
-                         (when-some [idx (aget copy-map i)]
-                           (aset res i (#?(:cljs da/aget :clj get) t2 idx))))
-                       res))
-                   (next rels)
-                   symbols))))
-      acc)))
+   (cond+
+     :let [rel (first rels)]
+ 
+     (nil? rel) acc
+ 
+     ;; one empty rel means final set has to be empty
+     (empty? (:tuples rel)) []
+ 
+     :let [keep-attrs (select-keys (:attrs rel) symbols)]
+ 
+     (empty? keep-attrs) (recur acc (next rels) symbols)
+ 
+     :let [copy-map (to-array (map #(get keep-attrs %) symbols))
+           len      (count symbols)]
+
+     :else
+     (recur
+       (for [#?(:cljs t1
+                :clj ^{:tag "[[Ljava.lang.Object;"} t1) acc
+             t2 (:tuples rel)]
+         (let [res (aclone t1)]
+           (dotimes [i len]
+             (when-some [idx (aget copy-map i)]
+               (aset res i (#?(:cljs da/aget :clj get) t2 idx))))
+           res))
+       (next rels)
+       symbols))))
 
 (defn collect [context symbols]
   (->> (-collect context symbols)

test/datascript/test/query.cljc

@@ -9,7 +9,6 @@
       (:import [clojure.lang ExceptionInfo])))
 
 
-
 (deftest test-joins
   (let [db (-> (d/empty-db)
                (d/db-with [ { :db/id 1, :name  "Ivan", :age   15 }
@@ -231,5 +230,16 @@
               "X")
          #{["abcX"] ["aXb"]})))
 
+
+(deftest ^{:doc "issue-385"} test-join-unrelated
+  (is (= #{}
+        (d/q '[:find ?name
+               :in $ ?my-fn
+               :where [?e :person/name ?name]
+                      [(?my-fn) ?result]
+                      [(< ?result 3)]]
+          (d/db-with (d/empty-db) [{:person/name "Joe"}])
+          (fn [] 5)))))
+
 #_(require 'datascript.test.query :reload)
 #_(clojure.test/test-ns 'datascript.test.query)