city may be null

apps/search_indexes/serializers.py

@@ -119,6 +119,12 @@ class AnotherCityDocumentShortSerializer(CityDocumentShortSerializer):
 
     country = CountryDocumentSerializer()
 
+    def to_representation(self, instance):
+        if instance != AttrDict(d={}) or \
+                (isinstance(instance, dict) and len(instance) != 0):
+            return super().to_representation(instance)
+        return None
+
 
 class ProductEstablishmentDocumentSerializer(serializers.Serializer):
     """Related to Product Establishment ES document serializer."""