Define AbsencesBatchCreateMutation's required arguments

aleksis/apps/alsijil/schema/absences.py

@@ -12,11 +12,11 @@ class LessonsForPersonType(graphene.ObjectType):
 
 class AbsencesBatchCreateMutation(graphene.Mutation):
     class Arguments:
-        persons = graphene.List(graphene.ID)
-        start = graphene.Date()
-        end = graphene.Date()
-        comment = graphene.String()
-        reason = graphene.ID()
+        persons = graphene.List(graphene.ID, required=True)
+        start = graphene.Date(required=True)
+        end = graphene.Date(required=True)
+        comment = graphene.String(required=False)
+        reason = graphene.ID(required=True)
 
     ok = graphene.Boolean()