Fix an error occuring on DB pagination for elements with common corpus, type and name

arkindex/documents/api/elements.py

@@ -144,9 +144,10 @@ class ElementsList(CorpusACLMixin, ListAPIView):
             )
             filtered_queryset = filtered_queryset.prefetch_related(best_classifications_prefetch)
 
+        # ID is required by postgres to order elements with common corpus, type and name
         return filtered_queryset \
             .prefetch_related('corpus', 'zone__image__server', 'type') \
-            .order_by('corpus', 'type__slug', 'name')
+            .order_by('corpus', 'type__slug', 'name', 'id')
 
 
 class ElementRetrieve(RetrieveUpdateDestroyAPIView):