Fix missing Discount.is_available_by_time method

src/pretix/base/models/discount.py

@@ -28,6 +28,7 @@ from typing import Dict, Optional, Tuple
 from django.core.exceptions import ValidationError
 from django.core.validators import MinValueValidator
 from django.db import models
+from django.utils.timezone import now
 from django.utils.translation import gettext_lazy as _, pgettext_lazy
 from django_scopes import ScopedManager
 
@@ -198,6 +199,14 @@ class Discount(LoggedModel):
             'subevent_mode': self.subevent_mode,
         })
 
+    def is_available_by_time(self, now_dt=None) -> bool:
+        now_dt = now_dt or now()
+        if self.available_from and self.available_from > now_dt:
+            return False
+        if self.available_until and self.available_until < now_dt:
+            return False
+        return True
+
     def _apply_min_value(self, positions, idx_group, result):
         if self.condition_min_value and sum(positions[idx][2] for idx in idx_group) < self.condition_min_value:
             return