Improve session inheritation

src/pretix/control/views/dashboards.py

@@ -184,6 +184,7 @@ def event_index(request, organizer, event):
         s['pretix_event_access_{}'.format(request.event.pk)] = request.session.session_key
         s.create()
         ctx['new_session'] = s.session_key
+        request.session['event_access'] = True
 
     for a in ctx['actions']:
         a.display = a.display(request)

src/pretix/presale/utils.py

@@ -73,7 +73,12 @@ def _detect_event(request, require_live=True):
                 )
                 if not can_access and 'pretix_event_access_{}'.format(request.event.pk) in request.session:
                     sparent = SessionStore(request.session.get('pretix_event_access_{}'.format(request.event.pk)))
-                    can_access = sparent.exists(request.session.get('pretix_event_access_{}'.format(request.event.pk)))
+                    try:
+                        parentdata = sparent.load()
+                    except:
+                        pass
+                    else:
+                        can_access = 'event_access' in parentdata
 
                 if not can_access:
                     raise PermissionDenied(_('The selected ticket shop is currently not available.'))

src/pretix/presale/views/event.py

@@ -118,10 +118,15 @@ class EventAuth(View):
             raise PermissionDenied(_('Please go back and try again.'))
 
         parent = data.get('pretix_event_access_{}'.format(request.event.pk))
-        sparent = SessionStore(parent)
 
-        if not sparent.exists(parent):
+        sparent = SessionStore(parent)
+        try:
+            parentdata = sparent.load()
+        except:
             raise PermissionDenied(_('Please go back and try again.'))
+        else:
+            if 'event_access' not in parentdata:
+                raise PermissionDenied(_('Please go back and try again.'))
 
         request.session['pretix_event_access_{}'.format(request.event.pk)] = parent
         return redirect(eventreverse(request.event, 'presale:event.index'))