Merge pull request #481 from johannaengland/destination-is-deletable

Make DestinationConfig.is_deletable behave according to name

src/argus/notificationprofile/media/base.py

@@ -16,6 +16,12 @@
 
 
 class NotificationMedium(ABC):
+    class NotDeletableError(Exception):
+        """
+        Custom exception class that is raised when a destination cannot be
+        deleted
+        """
+
     @classmethod
     @abstractmethod
     def validate(cls, instance: RequestDestinationConfigSerializer, dict: dict) -> dict:
@@ -39,11 +45,11 @@ def send(event: Event, destinations: QuerySet[DestinationConfig], **kwargs) -> b
         """Sends message about a given event to the given destinations"""
         pass
 
-    @staticmethod
-    def is_deletable(destination: DestinationConfig) -> Union[str, NoneType]:
+    @classmethod
+    def raise_if_not_deletable(cls, destination: DestinationConfig):
         """
-        Returns None if the given destination is able to be deleted and
-        returns an error message if not
+        Returns None if the given destination is deletable and raises an
+        NotDeletableError if not
         """
         return None
 

src/argus/notificationprofile/media/email.py

@@ -80,27 +80,24 @@ def validate(cls, instance: RequestDestinationConfigSerializer, email_dict: dict
 
         return form.cleaned_data
 
-    @staticmethod
-    def is_deletable(destination: DestinationConfig) -> Union[str, NoneType]:
+    @classmethod
+    def raise_if_not_deletable(cls, destination: DestinationConfig) -> Union[str, NoneType]:
         """
-        Returns None if the given email destination is able to be deleted
-        and an error message if it was defined by an outside source or
-        is in use by any notification profiles
+        Raises a NotDeletableError if the given email destination is not able
+        to be deleted (if it was defined by an outside source or is in use by
+        any notification profiles)
         """
         if destination.settings["synced"]:
-            return "Cannot delete this email destination since it was defined by an outside source."
+            raise cls.NotDeletableError(
+                "Cannot delete this email destination since it was defined by an outside source."
+            )
 
         connected_profiles = destination.notification_profiles.all()
         if connected_profiles:
             profiles = ", ".join([str(profile) for profile in connected_profiles])
-            return "".join(
-                [
-                    "Cannot delete this destination since it is in use in the notification profile(s): ",
-                    profiles,
-                    ".",
-                ]
+            raise cls.NotDeletableError(
+                f"Cannot delete this destination since it is in use in the notification profile(s): {profiles}."
             )
-        return None
 
     @staticmethod
     def update(destination: DestinationConfig, validated_data: dict) -> Union[DestinationConfig, NoneType]:

src/argus/notificationprofile/views.py

@@ -14,6 +14,7 @@
 from argus.drf.permissions import IsOwner
 from argus.incident.serializers import IncidentSerializer
 from argus.notificationprofile.media import MEDIA_CLASSES_DICT
+from argus.notificationprofile.media.base import NotificationMedium
 from .models import DestinationConfig, Filter, Media, NotificationProfile, Timeslot
 from .serializers import (
     FilterSerializer,
@@ -170,11 +171,12 @@ def destroy(self, request, *args, **kwargs):
         except DestinationConfig.DoesNotExist:
             raise ValidationError(f"Destination with pk={pk} does not exist.")
 
-        error_message = MEDIA_CLASSES_DICT[destination.media.slug].is_deletable(destination)
-        if not error_message:
-            return super().destroy(destination)
+        try:
+            MEDIA_CLASSES_DICT[destination.media.slug].raise_if_not_deletable(destination)
+        except NotificationMedium.NotDeletableError as e:
+            raise ValidationError(str(e))
         else:
-            raise ValidationError(error_message)
+            return super().destroy(destination)
 
 
 class TimeslotViewSet(viewsets.ModelViewSet):