added an api for setting the categories and listing them in the devices path

website/pushnotifications/api/permissions.py

+from django.db.models import QuerySet
 from rest_framework import permissions
 
 
 class IsOwner(permissions.BasePermission):
     def has_object_permission(self, request, view, obj):
+        if isinstance(obj, QuerySet):
+            return True
         # must be the owner to view the object
         return obj.user == request.user

website/pushnotifications/api/serializers.py

@@ -2,14 +2,28 @@ from __future__ import absolute_import
 
 from rest_framework.serializers import ModelSerializer
 
-from pushnotifications.models import Device
+from pushnotifications.models import Device, Category
 
 
 class DeviceSerializer(ModelSerializer):
     class Meta:
         model = Device
 
-        fields = ('pk', 'registration_id', 'active', 'date_created', 'type')
+        fields = (
+            'pk',
+            'registration_id',
+            'active',
+            'date_created',
+            'type',
+            'receive_category'
+        )
         read_only_fields = ('date_created',)
 
         extra_kwargs = {'active': {'default': True}}
+
+
+class CategorySerializer(ModelSerializer):
+    class Meta:
+        model = Category
+
+        fields = ('key', 'name')

website/pushnotifications/api/viewsets.py

 from rest_framework import permissions
+from rest_framework.decorators import list_route
+from rest_framework.response import Response
 from rest_framework.viewsets import ModelViewSet
 
 from pushnotifications.api.permissions import IsOwner
-from pushnotifications.api.serializers import DeviceSerializer
-from pushnotifications.models import Device
+from pushnotifications.api.serializers import DeviceSerializer, \
+    CategorySerializer
+from pushnotifications.models import Device, Category
 
 
 class DeviceViewSet(ModelViewSet):
@@ -27,3 +30,9 @@ class DeviceViewSet(ModelViewSet):
 
     def perform_update(self, serializer):
         serializer.save(user=self.request.user)
+
+    @list_route()
+    def categories(self, request):
+        categories = Category.objects.all()
+        serializer = CategorySerializer(categories, many=True)
+        return Response(serializer.data)

website/pushnotifications/models.py

@@ -70,6 +70,7 @@ class Message(models.Model):
     )
     category = models.ForeignKey(
         Category,
+        on_delete=models.CASCADE,
         verbose_name=_('category'),
         default="general"
     )