exclude booked timeslots in invitation form

scheduler/main/views.py

@@ -21,6 +21,7 @@ from collections import OrderedDict
 from django.conf import settings
 from django.contrib.auth.mixins import LoginRequiredMixin
 from django.contrib import messages
+from django.db import models
 from django.core.exceptions import PermissionDenied
 from django.http import HttpResponse
 from django.http import JsonResponse
@@ -89,7 +90,9 @@ class InvitationUpdateView(UpdateView):
     def get_context_data(self, **kwargs):
         context = super().get_context_data(**kwargs)
 
-        timeslots = list(self.object.schedule.timeslot_set.all())
+        timeslots = list(self.object.schedule.timeslot_set.filter(
+            models.Q(invitation=None) | models.Q(invitation=self.object)
+        ))
 
         dates = []
         times = []