Allow to change length of invoice numbers

src/pretix/api/serializers/event.py

@@ -597,6 +597,7 @@ class EventSettingsSerializer(serializers.Serializer):
         'invoice_numbers_consecutive',
         'invoice_numbers_prefix',
         'invoice_numbers_prefix_cancellations',
+        'invoice_numbers_counter_length',
         'invoice_attendee_name',
         'invoice_include_expire_date',
         'invoice_address_explanation_text',

src/pretix/base/models/invoices.py

@@ -116,8 +116,8 @@ class Invoice(models.Model):
     objects = ScopedManager(organizer='event__organizer')
 
     @staticmethod
-    def _to_numeric_invoice_number(number):
-        return '{:05d}'.format(int(number))
+    def _to_numeric_invoice_number(number, places):
+        return ('{:0%dd}' % places).format(int(number))
 
     @property
     def full_invoice_from(self):
@@ -173,7 +173,7 @@ class Invoice(models.Model):
         ]
         return '\n'.join([p.strip() for p in parts if p and p.strip()])
 
-    def _get_numeric_invoice_number(self):
+    def _get_numeric_invoice_number(self, c_length):
         numeric_invoices = Invoice.objects.filter(
             event__organizer=self.event.organizer,
             prefix=self.prefix,
@@ -182,7 +182,7 @@ class Invoice(models.Model):
         ).aggregate(
             max=Max('numeric_number')
         )['max'] or 0
-        return self._to_numeric_invoice_number(numeric_invoices + 1)
+        return self._to_numeric_invoice_number(numeric_invoices + 1, c_length)
 
     def _get_invoice_number_from_order(self):
         return '{order}-{count}'.format(
@@ -209,7 +209,7 @@ class Invoice(models.Model):
                 self.prefix += 'TEST-'
             for i in range(10):
                 if self.event.settings.get('invoice_numbers_consecutive'):
-                    self.invoice_no = self._get_numeric_invoice_number()
+                    self.invoice_no = self._get_numeric_invoice_number(self.event.settings.invoice_numbers_counter_length)
                 else:
                     self.invoice_no = self._get_invoice_number_from_order()
                 try:

src/pretix/base/settings.py

@@ -309,6 +309,16 @@ DEFAULTS = {
             help_text=_("The expiration date will not be shown if the invoice is generated after the order is paid."),
         )
     },
+    'invoice_numbers_counter_length': {
+        'default': '5',
+        'type': int,
+        'form_class': forms.IntegerField,
+        'serializer_class': serializers.IntegerField,
+        'form_kwargs': dict(
+            label=_("Minimum length of invoice number after prefix"),
+            help_text=_("The part of your invoice number after your prefix will be filled up with leading zeros up to this length, e.g. INV-001 or INV-00001."),
+        )
+    },
     'invoice_numbers_consecutive': {
         'default': 'True',
         'type': bool,

src/pretix/control/forms/event.py

@@ -677,6 +677,7 @@ class InvoiceSettingsForm(SettingsForm):
         'invoice_numbers_consecutive',
         'invoice_numbers_prefix',
         'invoice_numbers_prefix_cancellations',
+        'invoice_numbers_counter_length',
         'invoice_address_explanation_text',
         'invoice_email_attachment',
         'invoice_address_from_name',

src/pretix/control/templates/pretixcontrol/event/invoicing.html

@@ -19,6 +19,7 @@
                 {% bootstrap_field form.invoice_numbers_consecutive layout="control" %}
                 {% bootstrap_field form.invoice_numbers_prefix layout="control" %}
                 {% bootstrap_field form.invoice_numbers_prefix_cancellations layout="control" %}
+                {% bootstrap_field form.invoice_numbers_counter_length layout="control" %}
             </fieldset>
             <fieldset>
                 <legend>{% trans "Address form" %}</legend>