Improved invoice file names

src/pretix/base/models/invoices.py

@@ -9,7 +9,7 @@ from django.db.models import Max
 
 def invoice_filename(instance, filename: str) -> str:
     secret = ''.join(random.choice(string.ascii_letters + string.digits) for _ in range(14))
-    return 'invoices/{org}/{ev}/{ev}-{no}-{code}-{secret}.pdf'.format(
+    return 'invoices/{org}/{ev}/{ev}-{no:05d}-{code}-{secret}.pdf'.format(
         org=instance.event.organizer.slug, ev=instance.event.slug,
         no=instance.invoice_no, code=instance.order.code,
         secret=secret

src/pretix/base/settings.py

@@ -67,7 +67,7 @@ DEFAULTS = {
     },
     'invoice_generate': {
         'default': 'False',
-        'type': bool
+        'type': str
     },
     'invoice_address_from': {
         'default': '',