Add signal invoice_line_text

src/pretix/base/services/invoices.py

@@ -24,7 +24,7 @@ from pretix.base.models import Invoice, InvoiceAddress, InvoiceLine, Order
 from pretix.base.models.tax import EU_CURRENCIES
 from pretix.base.services.tasks import TransactionAwareTask
 from pretix.base.settings import GlobalSettingsObject
-from pretix.base.signals import periodic_task
+from pretix.base.signals import invoice_line_text, periodic_task
 from pretix.celery_app import app
 from pretix.helpers.database import rolledback_transaction
 from pretix.helpers.models import modelcopy
@@ -139,6 +139,9 @@ def build_invoice(invoice: Invoice) -> Invoice:
                 desc = "  + " + desc
             if invoice.event.settings.invoice_attendee_name and p.attendee_name:
                 desc += "<br />" + pgettext("invoice", "Attendee: {name}").format(name=p.attendee_name)
+            for recv, resp in invoice_line_text.send(sender=invoice.event, position=p):
+                if resp:
+                    desc += "<br/>" + resp
 
             for answ in p.answers.all():
                 if not answ.question.print_on_invoice:

src/pretix/base/signals.py

@@ -622,3 +622,11 @@ order_split = EventPluginSignal(
 This signal is sent out when an order is split into two orders and allows you to copy related models
 to the new order. You will be passed the old order as ``original`` and the new order as ``split_order``.
 """
+
+invoice_line_text = EventPluginSignal(
+    providing_args=["position"]
+)
+"""
+This signal is sent out when an invoice is built for an order. You can return additional text that
+should be shown on the invoice for the given ``position``.
+"""