def save(self, force_insert=False, force_update=False):
self.slug = slugify(self.title,
instance=self,
invalid=('actions', 'teachers'),
extra_lookup={'course': self.course})
if not self.position:
self.position = len(Lesson.objects.filter(course=self.course)) + 1
super(Lesson, self).save(force_insert, force_update)
def save(self, force_insert=False, force_update=False):
self.slug = slugify(self.title,
invalid=("create", "invitations", "requests"),
instance=self)
super(Course, self).save(force_insert, force_update)
