Delete follows pre_delete DICOMImageSetUpload

Author: koopmant

app/grandchallenge/cases/models.py

@@ -1392,3 +1392,17 @@ def convert_image_set_to_internal(self, *, image_set_id):
         image = Image(dicom_image_set=dicom_image_set, name=self.name)
         image.full_clean()
         image.save()
+
+
+@receiver(pre_delete, sender=DICOMImageSetUpload)
+def delete_dicom_upload_follows(*_, instance: DICOMImageSetUpload, **__):
+    """
+    Deletes the related follows.
+
+    We use a signal rather than overriding delete() to catch usages of
+    bulk_delete.
+    """
+    ct = ContentType.objects.filter(
+        app_label=instance._meta.app_label, model=instance._meta.model_name
+    ).get()
+    Follow.objects.filter(object_id=instance.pk, content_type=ct).delete()