fix empty speaker identifiers

models/database.py

@@ -167,9 +167,9 @@ class Speaker(db.Model):
         )
 
     def identifier(self):
-        if self.number == 0:
+        if self.number == None:
             return self.name
-        elif self.name == "":
+        elif self.name == None:
             return self.number
         else:
             return "{} ({})".format(self.name, self.number)

utils.py

@@ -18,7 +18,7 @@ def speaker_by_name_or_number(name_or_number, event_id):
         if speaker is not None:
             return speaker
         else:
-            speaker = Speaker("", number, event_id)
+            speaker = Speaker(None, number, event_id)
             db.session.add(speaker)
             db.session.commit()
             return speaker
@@ -28,7 +28,7 @@ def speaker_by_name_or_number(name_or_number, event_id):
         if speaker is not None:
             return speaker
         else:
-            speaker = Speaker(name, 0, event_id)
+            speaker = Speaker(name, None, event_id)
             db.session.add(speaker)
             db.session.commit()
             return speaker