Documents: Add default filtering of stubs

Add filter(is_stub) to the default Document model manager.

Now only the Passthrough manager can access document stubs.

Remove the explicit filtering of stubs from code that obtains
the queryset from the default document manager.

Signed-off-by: Roberto Rosario <roberto.rosario.gonzalez@gmail.com>

mayan/apps/documents/managers.py

@@ -17,17 +17,13 @@ logger = logging.getLogger(__name__)
 
 
 class DocumentManager(models.Manager):
-    def delete_stubs(self):
-        for stale_stub_document in self.filter(is_stub=True, date_added__lt=now() - timedelta(seconds=STUB_EXPIRATION_INTERVAL)):
-            stale_stub_document.delete(trash=False)
-
     def get_by_natural_key(self, uuid):
         return self.model.passthrough.get(uuid=force_text(uuid))
 
     def get_queryset(self):
         return TrashCanQuerySet(
             self.model, using=self._db
-        ).filter(in_trash=False)
+        ).filter(in_trash=False).filter(is_stub=False)
 
     def invalidate_cache(self):
         for document in self.model.objects.all():
@@ -222,7 +218,9 @@ class FavoriteDocumentManager(models.Manager):
 
 
 class PassthroughManager(models.Manager):
-    pass
+    def delete_stubs(self):
+        for stale_stub_document in self.filter(is_stub=True, date_added__lt=now() - timedelta(seconds=STUB_EXPIRATION_INTERVAL)):
+            stale_stub_document.delete(to_trash=False)
 
 
 class RecentDocumentManager(models.Manager):