add /shipping_vouchers endpoint

core/tickets/models.py

@@ -1,4 +1,5 @@
 from django.db import models
+from django.utils import timezone
 from django_softdelete.models import SoftDeleteModel
 
 from authentication.models import ExtendedUser
@@ -116,3 +117,20 @@ class Assignment(models.Model):
 
     def __str__(self):
         return str(self.issue_thread) + ' assigned to ' + self.assigned_to.username
+
+
+class ShippingVoucher(models.Model):
+    id = models.AutoField(primary_key=True)
+    issue_thread = models.ForeignKey(IssueThread, on_delete=models.CASCADE, related_name='shipping_vouchers', null=True)
+    voucher = models.CharField(max_length=255)
+    type = models.CharField(max_length=255)
+    timestamp = models.DateTimeField(auto_now_add=True)
+    used_at = models.DateTimeField(null=True)
+
+    def __str__(self):
+        return self.voucher + ' (' + self.type + ')'
+
+    def save(self, *args, **kwargs):
+        if self.used_at is None and self.issue_thread is not None:
+            self.used_at = timezone.now()
+        super().save(*args, **kwargs)