Adding the missing method to serialize

apps/rp/api/serializers.py

@@ -13,6 +13,9 @@ class TagListSerializer(serializers.Field):
             return [tag.name for tag in obj.all()]
         return obj
 
+    def to_internal_value(self, data):
+        return [tag.strip() for tag in data.split(",")]
+
 
 class ArticleSerializer(serializers.ModelSerializer):
     #: List of short tags to describe the article (eg. "Privacy", "Copyright")