use .set instead of direct assessment for ManyToManyField

program/serializers.py

@@ -274,12 +274,12 @@ class ShowSerializer(serializers.HyperlinkedModelSerializer):
         show = Show.objects.create(**validated_data)
 
         # Save many-to-many relationships
-        show.owners = owners
-        show.category = category
-        show.hosts = hosts
-        show.language = language
-        show.topic = topic
-        show.musicfocus = musicfocus
+        show.owners.set(owners)
+        show.category.set(category)
+        show.hosts.set(hosts)
+        show.language.set(language)
+        show.topic.set(topic)
+        show.musicfocus.set(musicfocus)
 
         show.save()
         return show
@@ -306,12 +306,12 @@ class ShowSerializer(serializers.HyperlinkedModelSerializer):
 
         # Only superusers may update the following fields
         if user.is_superuser:
-            instance.owners = validated_data.get('owners', instance.owners)
-            instance.category = validated_data.get('category', instance.category)
-            instance.hosts = validated_data.get('hosts', instance.hosts)
-            instance.language = validated_data.get('language', instance.language)
-            instance.topic = validated_data.get('topic', instance.topic)
-            instance.musicfocus = validated_data.get('musicfocus', instance.musicfocus)
+            instance.owners.set(validated_data.get('owners', instance.owners))
+            instance.category.set(validated_data.get('category', instance.category))
+            instance.hosts.set(validated_data.get('hosts', instance.hosts))
+            instance.language.set(validated_data.get('language', instance.language))
+            instance.topic.set(validated_data.get('topic', instance.topic))
+            instance.musicfocus.set(validated_data.get('musicfocus', instance.musicfocus))
             instance.type = validated_data.get('type', instance.type)
             instance.fundingcategory = validated_data.get('fundingcategory', instance.fundingcategory)
             instance.predecessor = validated_data.get('predecessor', instance.predecessor)
@@ -466,4 +466,4 @@ class NoteSerializer(serializers.ModelSerializer):
             except ObjectDoesNotExist:
                 pass
 
-        return instance
\ No newline at end of file
+        return instance