Update JSONEncoder to accept FileStorage objects

atst/utils/json.py

@@ -1,4 +1,5 @@
 from flask.json import JSONEncoder
+from werkzeug.datastructures import FileStorage
 from datetime import date
 from atst.models.attachment import Attachment
 
@@ -7,6 +8,8 @@ class CustomJSONEncoder(JSONEncoder):
     def default(self, obj):
         if isinstance(obj, Attachment):
             return obj.filename
-        if isinstance(obj, date):
+        elif isinstance(obj, date):
             return obj.strftime("%Y-%m-%d")
+        elif isinstance(obj, FileStorage):
+            return obj.filename
         return JSONEncoder.default(self, obj)