Fix, add es6 docker image and compose

Author: barseghyanartur

docker-compose-es-6-8.yml

@@ -0,0 +1,26 @@
+version: '3'
+
+services:
+
+  elasticsearch:
+    container_name: django_elasticsearch_dsl_drf_elasticsearch_es_6_8
+    build:
+      context: .
+      dockerfile: ./docker/elasticsearch/Dockerfile-ES-6-8
+    image: docker.elastic.co/elasticsearch/elasticsearch:6.8.15
+    volumes:
+    - esdata68:/usr/share/elasticsearch/data
+    ports:
+    - "9200:9200"
+    - "9300:9300"
+    environment:
+#    - bootstrap.memory_lock=true
+    - discovery.type=single-node
+    - xpack.security.enabled=false
+    - cluster.routing.allocation.disk.watermark.low=97%
+    - cluster.routing.allocation.disk.watermark.high=98%
+    - cluster.routing.allocation.disk.watermark.flood_stage=99%
+    - "ES_JAVA_OPTS=-Xms512m -Xmx512m"
+
+volumes:
+  esdata68:

docker/elasticsearch/Dockerfile-ES-6-8

@@ -0,0 +1,5 @@
+FROM docker.elastic.co/elasticsearch/elasticsearch:6.8.15
+ADD ./docker/elasticsearch/elasticsearch.yml /usr/share/elasticsearch/config/
+USER root
+RUN chown elasticsearch:elasticsearch config/elasticsearch.yml
+USER elasticsearch

src/django_elasticsearch_dsl_drf/viewsets.py

@@ -217,14 +217,12 @@ def get_object(self):
 
             if not obj and self.ignore:
                 raise Http404("No result matches the given query.")
-            # TODO: Do we need obj on != ELASTICSEARCH_GTE_7_0 like below?
-            if ELASTICSEARCH_GTE_7_0:
-                dictionary_proxy = self.dictionary_proxy(
-                    obj.to_dict(),
-                    obj.meta
-                )
-            else:
-                dictionary_proxy = self.dictionary_proxy(obj, obj.meta)
+            # Remark 1: Code below works fine. Do not try to do the same as
+            # done in `Remark 2`.
+            dictionary_proxy = self.dictionary_proxy(
+                obj.to_dict(),
+                getattr(obj, 'meta', None)
+            )
             return dictionary_proxy
         else:
             queryset = queryset.filter(
@@ -241,6 +239,8 @@ def get_object(self):
                 # May raise a permission denied
                 self.check_object_permissions(self.request, obj)
 
+                # Remark 2: Unlike code in `Remark 1`, here we do need the
+                # conditional treatment.
                 if ELASTICSEARCH_GTE_7_0:
                     dictionary_proxy = self.dictionary_proxy(
                         obj.to_dict(),