Fix slot duration modification form

AKSubmission/forms.py

@@ -6,7 +6,7 @@ from django.core.exceptions import ValidationError
 from django.utils.translation import ugettext_lazy as _
 
 from AKModel.availability.forms import AvailabilitiesFormMixin
-from AKModel.models import AK, AKOwner, AKCategory, AKRequirement, AKSlot, AKOrgaMessage
+from AKModel.models import AK, AKOwner, AKCategory, AKRequirement, AKSlot, AKOrgaMessage, Event
 
 
 class AKForm(AvailabilitiesFormMixin, forms.ModelForm):
@@ -165,9 +165,11 @@ class AKDurationForm(forms.ModelForm):
     def __init__(self, *args, **kwargs):
         super().__init__(*args, **kwargs)
         self.initial = {**self.initial, **kwargs['initial']}
-        event = self.initial.get('event')
-        if event is not None:
-            self.initial['duration'] = event.default_slot
+        if self.initial.get('duration') == 0:
+            event_id = self.initial.get('event')
+            if event_id is not None:
+                event = Event.objects.get(pk=event_id)
+                self.initial['duration'] = event.default_slot
 
 
 class AKOrgaMessageForm(forms.ModelForm):