Fix snapshot updating issues

nummi/main/models.py

@@ -76,7 +76,7 @@ class InvoiceForm(ModelForm):
 
 class Snapshot(models.Model):
     id = models.UUIDField(primary_key=True, default=uuid.uuid4, editable=False)
-    date = models.DateField(default=date.today, unique=True)
+    date = models.DateField(unique=True)
     value = models.DecimalField(max_digits=12, decimal_places=2, default=0)
     previous = models.OneToOneField(
         "self", on_delete=models.SET_NULL, blank=True, null=True, editable=False
@@ -98,13 +98,19 @@ class Snapshot(models.Model):
                 .filter(date__lt=self.date)
                 .first()
             )
-            print(_prev)
 
             try:
                 _next = self.__class__.objects.exclude(id=self.id).get(previous=_prev)
             except self.__class__.DoesNotExist:
                 pass
             else:
+                try:
+                    _prevnext = self.__class__.objects.exclude(id=self.id).get(previous=self)
+                except self.__class__.DoesNotExist:
+                    pass
+                else:
+                    _prevnext.previous = self.__class__.objects.order_by("-date").exclude(id=self.id).filter(date__lt=_prevnext.date).first()
+                    _prevnext.save(only_super=True)
                 _next.previous = self
                 _next.save(only_super=True)
 

nummi/main/views.py

@@ -142,7 +142,10 @@ def snapshot(request, date=None):
 
 @login_required
 def update_snapshot(request, uuid):
-    _snapshot, _ = Snapshot.objects.get_or_create(id=uuid)
+    try:
+        _snapshot = Snapshot.objects.get(id=uuid)
+    except Snapshot.DoesNotExist:
+        _snapshot = Snapshot(id=uuid)
     _form = SnapshotForm(request.POST, instance=_snapshot)
     _form.save()
     return redirect(snapshot, date=_snapshot.date)