fix: fix audio_url generation for notes

There were some problems during audio_url generation for notes:

1. the cba_id was never part of the Note serializer so getting
   values from the validated data needed to fail.
2. the get_audio_url utililty function returned None if
   no cba_id was provided if a the CBA_API_KEY was missing,
   but None but the respective model field is not nullable on the note.
3. Request or JSON decoder errors would bubble unhandled, even though
   audio_url generation seems to be optional and should not necessarily
   interfere with note creation.

program/serializers.py

@@ -453,6 +453,7 @@ class NoteSerializer(serializers.ModelSerializer):
     timeslot = serializers.PrimaryKeyRelatedField(queryset=TimeSlot.objects.all())
     host = serializers.PrimaryKeyRelatedField(queryset=Host.objects.all())
     thumbnails = serializers.SerializerMethodField()  # Read-only
+    cba_id = serializers.IntegerField(required=False, write_only=True)
 
     @staticmethod
     def get_thumbnails(note):
@@ -476,7 +477,7 @@ class NoteSerializer(serializers.ModelSerializer):
         validated_data["user_id"] = self.context["user_id"]
 
         # Try to retrieve audio URL from CBA
-        validated_data["audio_url"] = get_audio_url(validated_data["cba_id"])
+        validated_data["audio_url"] = get_audio_url(validated_data.get("cba_id", None))
 
         note = Note.objects.create(**validated_data)
 

program/utils.py

@@ -18,6 +18,7 @@
 # along with this program.  If not, see <http://www.gnu.org/licenses/>.
 #
 
+import json
 from datetime import date, datetime, time
 from typing import Dict, Optional, Tuple, Union
 
@@ -57,7 +58,7 @@ def parse_time(date_string: str) -> time:
     return datetime.strptime(date_string, "%H:%M:%S").time()
 
 
-def get_audio_url(cba_id):
+def get_audio_url(cba_id: Optional[int]) -> str:
     """
     Retrieve the direct URL to the mp3 in CBA
     In order to retrieve the URL, stations need
@@ -67,8 +68,8 @@ def get_audio_url(cba_id):
     For these contact cba@fro.at
     """
 
-    if cba_id is None or cba_id == "" or CBA_API_KEY == "":
-        return None
+    if not cba_id or CBA_API_KEY == "":
+        return ""
     else:
         if DEBUG:
             url = (
@@ -85,9 +86,11 @@ def get_audio_url(cba_id):
                 + CBA_API_KEY
             )
 
-        audio_url = requests.get(url).json()
-
-    return audio_url
+        try:
+            return requests.get(url).json()
+        except (requests.RequestException, json.JSONDecodeError):
+            # TODO: we might want to add some logging
+            return ""
 
 
 def get_values(