Handle empty field selectors for signal enrichment in Gateway

Signed-off-by: Yannic Klem <Yannic.Klem@bosch.io>
eclipse-ditto · Apr 5, 2022 · c13a647 · c13a647
1 parent 81f6715
commit c13a647
Showing 1 changed file with 6 additions and 3 deletions.
diff --git a/...ice/src/main/java/org/eclipse/ditto/gateway/service/streaming/actors/SessionedSignal.java b/...ice/src/main/java/org/eclipse/ditto/gateway/service/streaming/actors/SessionedSignal.java
@@ -97,7 +97,7 @@ public CompletionStage<JsonObject> retrieveExtraFields(@Nullable final SignalEnr
                 newPlaceholderResolver(RequestPlaceholder.getInstance(), getDittoHeaders().getAuthorizationContext())
         );
         final Optional<ThingFieldSelector> resolvedExtraFields = session.getExtraFields()
-                .map(extraFields -> getExtraFields(expressionResolver, extraFields));
+                .flatMap(extraFields -> getExtraFields(expressionResolver, extraFields));
         if (resolvedExtraFields.isPresent()) {
             final Optional<ThingId> thingIdOptional = WithEntityId.getEntityIdOfType(ThingId.class, signal);
             if (facade != null && thingIdOptional.isPresent()) {
@@ -117,16 +117,19 @@ public CompletionStage<JsonObject> retrieveExtraFields(@Nullable final SignalEnr
         }
     }
 
-    private ThingFieldSelector getExtraFields(final ExpressionResolver expressionResolver,
+    private Optional<ThingFieldSelector> getExtraFields(final ExpressionResolver expressionResolver,
             final ThingFieldSelector thingFieldSelector) {
         final List<JsonPointer> jsonPointers = thingFieldSelector.getPointers().stream()
                 .map(JsonPointer::toString)
                 .map(expressionResolver::resolve)
                 .flatMap(PipelineElement::toStream)
                 .map(JsonPointer::of)
                 .collect(Collectors.toList());
+        if(jsonPointers.isEmpty()) {
+            return Optional.empty();
+        }
         final JsonFieldSelector jsonFieldSelector = JsonFactory.newFieldSelector(jsonPointers);
-        return ThingFieldSelector.fromJsonFieldSelector(jsonFieldSelector);
+        return Optional.of(ThingFieldSelector.fromJsonFieldSelector(jsonFieldSelector));
     }
 
     @Override