Resolve "two visits with the same dates"

Closes #369 (closed), #373 (closed), #372 (closed), #370 (closed)

smash/web/models/visit.py

@@ -126,16 +126,17 @@ class Visit(models.Model):
         self.save()
         return
 
+
 @receiver(post_save, sender=Visit)
 def check_visit_number(sender, instance, created, **kwargs):
-    # no other solution to ensure the visit_number is in cronological order than to sort the whole list if there are future visits
+    # no other solution to ensure the visit_number is in chronological order than to sort the whole list if there are future visits
     visit = instance
     if visit.subject is not None: #not sure if select_for_update has an effect, the tests work as well without it
         #new visit, sort only future visit respect to the new one
         if created:
             visits_before = Visit.objects.select_for_update().filter(subject=visit.subject).filter(datetime_begin__lt=visit.datetime_begin).count()
             # we need to sort the future visits respect to the new one, if any
-            visits = Visit.objects.select_for_update().filter(subject=visit.subject).filter(datetime_begin__gte=visit.datetime_begin).order_by('datetime_begin','datetime_end')
+            visits = Visit.objects.select_for_update().filter(subject=visit.subject).filter(datetime_begin__gte=visit.datetime_begin).order_by('datetime_begin','id')
             with transaction.atomic(): #not sure if it has an effect, the tests work as well without it
                 for i, v in enumerate(visits):
                     expected_visit_number = (visits_before + i + 1)
@@ -143,10 +144,10 @@ def check_visit_number(sender, instance, created, **kwargs):
                         Visit.objects.filter(id=v.id).update(visit_number=expected_visit_number) # does not rise post_save, we avoid recursion
                         if v.id == visit.id: #if the iteration visit is the same that the instance that produced the signal call
                             #this ensures that the upper saved object is also updated, otherwise, refresh_from_db should be called
-                            visit.visit_number = v.visit_number 
+                            visit.visit_number = v.visit_number
         else:
             #if visits are modified, then, check everything
-            visits = Visit.objects.select_for_update().filter(subject=visit.subject).order_by('datetime_begin','datetime_end')
+            visits = Visit.objects.select_for_update().filter(subject=visit.subject).order_by('datetime_begin','id')
             with transaction.atomic():
                 for i, v in enumerate(visits):
                     expected_visit_number = (i+1)