Merge pull request #1890 from eclipse-ditto/bugfix/1888-retrieving-arrays-in-fieldselectors

#1888 fix retrieving simple arrays via field selectors

Author: thjaeckle

json/src/main/java/org/eclipse/ditto/json/ImmutableJsonObject.java

@@ -432,8 +432,8 @@ private static JsonObject filterByTrie(final JsonObject self, final JsonFieldSel
                     filteredChildValue = filterByTrie(childValue.asObject(), trie.descend(key)); // recurse!
                 } else if (childValue.isArray()) {
                     filteredChildValue = childValue.asArray().stream()
-                            .filter(JsonValue::isObject)
-                            .map(value -> filterByTrie(value.asObject(), trie.descend(key))) // recurse!
+                            .map(value -> value.isObject() ? filterByTrie(value.asObject(), trie.descend(key)) // recurse!
+                                    : value)
                             .collect(JsonCollectors.valuesToArray());
                 } else {
                     filteredChildValue = childValue;

json/src/test/java/org/eclipse/ditto/json/ImmutableJsonObjectTest.java

@@ -1433,6 +1433,68 @@ public void partiallyIntersectingPointersHaveNoEffectInFieldSelector() {
         assertThat(actual).isEqualTo(underTest.remove("x"));
     }
 
+    @Test
+    public void nestedObjectsInsideArraysAreSelectedWhenSelectingViaFieldSelector() {
+        final JsonObject underTest = JsonObject.newBuilder()
+                .set("some", JsonObject.newBuilder()
+                        .set("nested", JsonArray.newBuilder()
+                                .add(JsonObject.newBuilder()
+                                        .set("a", 1)
+                                        .set("b", 2)
+                                        .set("c", 3)
+                                        .build()
+                                )
+                                .add(JsonObject.newBuilder()
+                                        .set("a", 11)
+                                        .set("b", 22)
+                                        .set("c", 33)
+                                        .build()
+                                )
+                                .build())
+                        .build()
+                )
+                .set("other", "foo")
+                .build();
+
+        final JsonFieldSelector selectorSelectingArray =
+                JsonFieldSelector.newInstance("some/nested/b");
+        final JsonObject actual = underTest.get(selectorSelectingArray);
+
+        final JsonObject expected = JsonObject.newBuilder()
+                .set("some", JsonObject.newBuilder()
+                        .set("nested", JsonArray.newBuilder()
+                                .add(JsonObject.newBuilder()
+                                        .set("b", 2)
+                                        .build()
+                                )
+                                .add(JsonObject.newBuilder()
+                                        .set("b", 22)
+                                        .build()
+                                )
+                                .build())
+                        .build()
+                )
+                .build();
+        assertThat(actual).isEqualTo(expected);
+    }
+
+    @Test
+    public void simpleArraysArePreservedWhenSelectingViaFieldSelector() {
+        final JsonObject underTest = JsonObject.newBuilder()
+                .set("some", JsonObject.newBuilder()
+                        .set("nested", JsonArray.newBuilder()
+                                .add(1, 2, 3)
+                                .build())
+                        .build()
+                )
+                .set("other", "foo")
+                .build();
+        final JsonFieldSelector selectorSelectingArray =
+                JsonFieldSelector.newInstance("some/nested");
+        final JsonObject actual = underTest.get(selectorSelectingArray);
+        assertThat(actual).isEqualTo(underTest.remove("other"));
+    }
+
     @Test
     public void jsonObjectsNestedInArraysShouldCompareWithoutFieldDefinitions() {
         final JsonObject objectWithoutDefinition =