[NOID] Return a node even if no relationships exist (#4168)

core/src/main/java/apoc/convert/Json.java

@@ -234,7 +234,6 @@ public Stream<MapResult> toTree(
  @Procedure("apoc.paths.toJsonTree")
  @Description(
  "apoc.paths.toJsonTree([paths],[lowerCaseRels=true], [config]) creates a stream of nested documents representing the graph as a tree by traversing outgoing relationships")
- // todo optinally provide root node
  public Stream<MapResult> pathsToTree(
  @Name("paths") List<Path> paths,
  @Name(value = "lowerCaseRels", defaultValue = "true") boolean lowerCaseRels,
@@ -254,6 +253,16 @@ public Stream<MapResult> pathsToTree(
  allPaths.forEach(path -> {
  // This api will always return relationships in an outgoing fashion ()-[r]->()
  var pathRelationships = path.relationships();
+ // If no relationships exist in the path, then add the node by itself
+ if (!pathRelationships.iterator().hasNext()) {
+ Node currentNode = path.startNode();
+ Long currentNodeId = currentNode.getId();
+
+ if (!visitedInOtherPaths.contains(currentNodeId)) {
+ nodesToKeepInResult.add(currentNodeId);
+ }
+ tree.computeIfAbsent(currentNode.getId(), (id) -> toMap(currentNode, nodes));
+ }
  pathRelationships.iterator().forEachRemaining((currentRel) -> {
  Node currentNode = currentRel.getStartNode();
  Long currentNodeId = currentNode.getId();

core/src/test/java/apoc/convert/PathsToJsonTreeTest.java

@@ -56,7 +56,7 @@ public void clear() {
  }
 
  @Test
- public void testToTreeSimplePath() throws Exception {
+ public void testToTreeSimplePath() {
  /* r:R
  a:A --------> b:B
  */
@@ -90,6 +90,68 @@ public void testToTreeSimplePath() throws Exception {
  }
  }
 
+ @Test
+ public void testSingleNode() {
+ // a:A
+ db.executeTransactionally("CREATE (a: A {nodeName: 'a'})");
+
+ var query = "MATCH path = (n)\n"
+ + "WITH COLLECT(path) AS paths\n"
+ + "CALL apoc.paths.toJsonTree(paths, true, {sortPaths: false}) YIELD value AS tree\n"
+ + "RETURN tree";
+
+ try (Transaction tx = db.beginTx()) {
+ Result result = tx.execute(query);
+ var rows = result.stream().collect(Collectors.toList());
+ var expectedRow = "{" + " \"tree\":{"
+ + " \"nodeName\":\"a\","
+ + " \"_type\":\"A\","
+ + " \"_id\":0"
+ + " }"
+ + "}";
+ assertEquals(rows.size(), 1);
+ assertEquals(parseJson(expectedRow), rows.get(0));
+ }
+ }
+
+ @Test
+ public void testSingleDisjointNodes() {
+ // a:A
+ db.executeTransactionally("CREATE (a: A {nodeName: 'a'}), (b: B {nodeName: 'b'}), (c: C {nodeName: 'c'})");
+
+ var query = "MATCH path = (n)\n"
+ + "WITH COLLECT(path) AS paths\n"
+ + "CALL apoc.paths.toJsonTree(paths, true, {sortPaths: false}) YIELD value AS tree\n"
+ + "RETURN tree";
+
+ try (Transaction tx = db.beginTx()) {
+ Result result = tx.execute(query);
+ var rows = result.stream().collect(Collectors.toList());
+ var expectedRowA = "{" + " \"tree\":{"
+ + " \"nodeName\":\"a\","
+ + " \"_type\":\"A\","
+ + " \"_id\":0"
+ + " }"
+ + "}";
+ var expectedRowB = "{" + " \"tree\":{"
+ + " \"nodeName\":\"b\","
+ + " \"_type\":\"B\","
+ + " \"_id\":1"
+ + " }"
+ + "}";
+ var expectedRowC = "{" + " \"tree\":{"
+ + " \"nodeName\":\"c\","
+ + " \"_type\":\"C\","
+ + " \"_id\":2"
+ + " }"
+ + "}";
+ assertEquals(rows.size(), 3);
+ assertEquals(parseJson(expectedRowA), rows.get(0));
+ assertEquals(parseJson(expectedRowB), rows.get(1));
+ assertEquals(parseJson(expectedRowC), rows.get(2));
+ }
+ }
+
  @Test
  public void testToTreeSimpleReversePath() {
  /* r:R