Add precondition viewset method implementation.

greenmine/base/api.py

@@ -1,16 +1,35 @@
 # -*- coding: utf-8 -*-
 
 from rest_framework import viewsets
+
 from .pagination import HeadersPaginationMixin, ConditionalPaginationMixin
 
 
-class ModelCrudViewSet(HeadersPaginationMixin,
+class PreconditionMixin(object):
+    def pre_conditions_on_save(self, obj):
+        pass
+
+    def pre_conditions_on_delete(self, obj):
+        pass
+
+    def pre_save(self, obj):
+        super().pre_save(obj)
+        self.pre_conditions_on_save(obj)
+
+    def pre_delete(self, obj):
+        super().pre_delete(obj)
+        self.pre_conditions_on_delete(obj)
+
+
+class ModelCrudViewSet(PreconditionMixin,
+                       HeadersPaginationMixin,
                        ConditionalPaginationMixin,
                        viewsets.ModelViewSet):
     pass
 
 
-class ModelListViewSet(HeadersPaginationMixin,
+class ModelListViewSet(PreconditionMixin,
+                       HeadersPaginationMixin,
                        ConditionalPaginationMixin,
                        viewsets.ReadOnlyModelViewSet):
     pass

greenmine/base/exceptions.py

@@ -45,6 +45,13 @@ class PermissionDenied(exceptions.PermissionDenied):
     pass
 
 
+class PreconditionError(BaseException):
+    """
+    Error raised on precondition method on viewset.
+    """
+    default_detail = "Precondition error"
+
+
 class InternalError(BaseException):
     """
     Exception for internal errors.

greenmine/projects/api.py

@@ -25,8 +25,8 @@ class ProjectViewSet(ModelCrudViewSet):
         return qs.distinct()
 
     def pre_save(self, obj):
-        super(ProjectViewSet, self).pre_save(obj)
         obj.owner = self.request.user
+        super(ProjectViewSet, self).pre_save(obj)
 
 
 # User Stories commin ViewSets

greenmine/projects/milestones/api.py

@@ -3,9 +3,9 @@
 from django.utils.translation import ugettext_lazy as _
 
 from rest_framework.permissions import IsAuthenticated
-from rest_framework.exceptions import ParseError
 
 from greenmine.base import filters
+from greenmine.base import exceptions as exc
 from greenmine.base.api import ModelCrudViewSet
 from greenmine.base.notifications.api import NotificationSenderMixin
 
@@ -24,11 +24,16 @@ class MilestoneViewSet(NotificationSenderMixin, ModelCrudViewSet):
     update_notification_template = "update_milestone_notification"
     destroy_notification_template = "destroy_milestone_notification"
 
-    def pre_save(self, obj):
+    def pre_conditions_on_save(self, obj):
-        super(MilestoneViewSet, self).pre_save(obj)
+        super().pre_conditions_on_save(obj)
-        if not obj.id:
-            obj.owner = self.request.user
 
         if (obj.project.owner != self.request.user and
                 obj.project.memberships.filter(user=self.request.user).count() == 0):
-            raise ParseError(detail=_("You must not add a new milestone to this project."))
+            raise exc.PreconditionError("You must not add a new milestone to this project.")
+
+    def pre_save(self, obj):
+        if not obj.id:
+            obj.owner = self.request.user
+
+        super().pre_save(obj)
+

greenmine/projects/userstories/api.py

@@ -4,9 +4,9 @@ from django.utils.translation import ugettext_lazy as _
 from django.contrib.contenttypes.models import ContentType
 
 from rest_framework.permissions import IsAuthenticated
-from rest_framework.exceptions import ParseError
 
 from greenmine.base import filters
+from greenmine.base import exceptions as exc
 from greenmine.base.api import ModelCrudViewSet
 from greenmine.base.notifications.api import NotificationSenderMixin
 from greenmine.projects.permissions import AttachmentPermission
@@ -29,16 +29,17 @@ class UserStoryAttachmentViewSet(ModelCrudViewSet):
 
     def get_queryset(self):
         ct = ContentType.objects.get_for_model(models.UserStory)
-        qs = super(UserStoryAttachmentViewSet, self).get_queryset()
+        qs = super().get_queryset()
         qs = qs.filter(content_type=ct)
         return qs.distinct()
 
     def pre_save(self, obj):
-        super(UserStoryAttachmentViewSet, self).pre_save(obj)
         if not obj.id:
             obj.content_type = ContentType.objects.get_for_model(models.UserStory)
             obj.owner = self.request.user
 
+        super().pre_save(obj)
+
 
 class UserStoryViewSet(NotificationSenderMixin, ModelCrudViewSet):
     model = models.UserStory
@@ -46,25 +47,31 @@ class UserStoryViewSet(NotificationSenderMixin, ModelCrudViewSet):
     permission_classes = (IsAuthenticated, permissions.UserStoryPermission)
     filter_backends = (filters.IsProjectMemberFilterBackend,)
     filter_fields = ['project', 'milestone', 'milestone__isnull']
+
     create_notification_template = "create_userstory_notification"
     update_notification_template = "update_userstory_notification"
     destroy_notification_template = "destroy_userstory_notification"
 
-    def pre_save(self, obj):
+    def pre_conditions_on_save(self, obj):
-        super(UserStoryViewSet, self).pre_save(obj)
+        super().pre_conditions_on_save(obj)
-        if not obj.id:
-            obj.owner = self.request.user
 
         if (obj.project.owner != self.request.user and
                 obj.project.memberships.filter(user=self.request.user).count() == 0):
-            raise ParseError(detail=_("You must not add a new user story to this project."))
+            raise exc.PreconditionError("You must not add a new user story to this project.")
 
         if obj.milestone and obj.milestone.project != obj.project:
-            raise ParseError(detail=_("You must not add a new user story to this milestone."))
+            raise exc.PreconditionError("You must not add a new user story to this milestone.")
+
+    def pre_save(self, obj):
+        if not obj.id:
+            obj.owner = self.request.user
+
+        super().pre_save(obj)
 
     def post_save(self, obj, created=False):
         with reversion.create_revision():
             if "comment" in self.request.DATA:
                 # Update the comment in the last version
                 reversion.set_comment(self.request.DATA['comment'])
-        super(UserStoryViewSet, self).post_save(obj, created)
+
+        super().post_save(obj, created)