Fix virtual node id working (#743)

Author: gem-neo4j

common/src/main/java/apoc/result/VirtualNode.java

@@ -47,7 +47,7 @@ public VirtualNode(Label[] labels, Map<String, Object> props) {
         this.id = MIN_ID.decrementAndGet();
         addLabels(asList(labels));
         this.props.putAll(props);
-        this.elementId = null;
+        this.elementId = UUID.randomUUID().toString();
     }
 
     @SuppressWarnings("unused") // used from extended
@@ -67,13 +67,14 @@ public VirtualNode(Node node, List<String> propertyNames, boolean wrapNodeIDs) {
         Objects.requireNonNull(node, ERROR_NODE_NULL);
         final long id = node.getId();
         // if node is already virtual, we return the same id
-        this.id = id < 0 || wrapNodeIDs ? id : -id - 1;
+        this.id = id < 0 || wrapNodeIDs ? id : MIN_ID.decrementAndGet();
+        this.elementId = id < 0 || wrapNodeIDs
+                ? node.getElementId()
+                : UUID.randomUUID().toString();
         // to not overlap this nodes ids with ids from VirtualNode(Label[] labels, Map<String, Object> props)
-        MIN_ID.updateAndGet(x -> Math.min(x, this.id));
         this.labels.addAll(Util.labelStrings(node));
         String[] keys = propertyNames.toArray(new String[propertyNames.size()]);
         this.props.putAll(node.getProperties(keys));
-        this.elementId = node.getElementId();
     }
 
     public VirtualNode(Node node, List<String> propertyNames) {

core/src/test/java/apoc/create/CreateTest.java

@@ -30,6 +30,7 @@
 import apoc.path.Paths;
 import apoc.util.TestUtil;
 import apoc.util.collection.Iterables;
+import java.util.HashSet;
 import java.util.Iterator;
 import java.util.List;
 import java.util.Map;
@@ -415,6 +416,62 @@ public void testVirtualFromNodeFunction() {
                 });
     }
 
+    @Test
+    public void test2VirtualFromNodesHaveUniqueIDs() {
+        testCall(
+                db,
+                """
+                        CREATE (n1:Cat { name:'Maja', born: 2023 } ), (n2:Cat { name:'Pelle', born: 2023 } )
+                        RETURN apoc.create.virtual.fromNode(n1, ['name']) AS node1, apoc.create.virtual.fromNode(n2, ['name']) AS node2
+                        """,
+                (row) -> {
+                    Node node1 = (Node) row.get("node1");
+
+                    assertTrue(node1.hasLabel(label("Cat")));
+                    var firstNodeID = node1.getId();
+                    assertTrue(node1.getId() < 0);
+                    assertEquals("Maja", node1.getProperty("name"));
+                    assertNull(node1.getProperty("born"));
+
+                    Node node2 = (Node) row.get("node2");
+
+                    assertTrue(node2.hasLabel(label("Cat")));
+                    var secondNodeID = node2.getId();
+                    assertTrue(node2.getId() < 0);
+                    assertEquals("Pelle", node2.getProperty("name"));
+                    assertNull(node2.getProperty("born"));
+
+                    assertNotEquals(firstNodeID, secondNodeID);
+                });
+    }
+
+    @Test
+    public void testVirtualFromSameNodesHaveUniqueIDs() {
+        testResult(
+                db,
+                """
+                        CREATE (n1:Cat { name:'Maja', born: 2023 } )
+                        WITH n1
+                        UNWIND [1,2,3] AS i
+                        RETURN apoc.create.virtual.fromNode(n1, ['name']) AS node1
+                        """,
+                (result) -> {
+                    HashSet<Long> nodeIDs = new HashSet<>();
+                    while (result.hasNext()) {
+                        Map<String, Object> r = result.next();
+                        Node node1 = (Node) r.get("node1");
+
+                        assertTrue(node1.hasLabel(label("Cat")));
+                        nodeIDs.add(node1.getId());
+                        assertTrue(node1.getId() < 0);
+                        assertEquals("Maja", node1.getProperty("name"));
+                        assertNull(node1.getProperty("born"));
+                    }
+
+                    assertEquals(3, nodeIDs.size());
+                });
+    }
+
     @Test
     public void testVirtualFromNodeFunctionWithWrapping() {
         testCall(