Add signal item_description

doc/development/api/general.rst

@@ -26,7 +26,7 @@ Frontend
 --------
 
 .. automodule:: pretix.presale.signals
-   :members: html_head, html_footer, footer_link, front_page_top, front_page_bottom, fee_calculation_for_cart, contact_form_fields, question_form_fields, checkout_confirm_messages, checkout_confirm_page_content, checkout_all_optional, html_page_header, sass_preamble, sass_postamble, render_seating_plan, checkout_flow_steps, position_info
+   :members: html_head, html_footer, footer_link, front_page_top, front_page_bottom, fee_calculation_for_cart, contact_form_fields, question_form_fields, checkout_confirm_messages, checkout_confirm_page_content, checkout_all_optional, html_page_header, sass_preamble, sass_postamble, render_seating_plan, checkout_flow_steps, position_info, item_description
 
 
 .. automodule:: pretix.presale.signals

src/pretix/presale/signals.py

@@ -256,3 +256,12 @@ invoice address, confirmations) will be optional, except for questions. Use with
 As with all plugin signals, the ``sender`` keyword argument will contain the event. A ``request``
 argument will contain the request object.
 """
+
+item_description = EventPluginSignal(
+    providing_args=["item", "variation"]
+)
+"""
+This signal is sent out when the description of an item or variation is rendered and allows you to append
+additional text to the description. You are passed the ``item`` and ``variation`` and expected to return
+HTML.
+"""

src/pretix/presale/views/event.py

@@ -22,6 +22,7 @@ from pretix.base.models.event import SubEvent
 from pretix.base.models.items import ItemBundle
 from pretix.multidomain.urlreverse import eventreverse
 from pretix.presale.ical import get_ical
+from pretix.presale.signals import item_description
 from pretix.presale.views.organizer import (
     EventListMixin, add_subevents_for_days, filter_qs_by_attr,
     weeks_for_template,
@@ -126,6 +127,11 @@ def get_grouped_items(event, subevent=None, voucher=None, channel='web', require
                 item._remove = True
                 continue
 
+        item.description = str(item.description)
+        for recv, resp in item_description.send(sender=event, item=item, variation=None):
+            if resp:
+                item.description += ("<br/>" if item.description else "") + resp
+
         if not item.has_variations:
             item._remove = False
             if not bool(item._subevent_quotas):
@@ -171,6 +177,11 @@ def get_grouped_items(event, subevent=None, voucher=None, channel='web', require
             display_add_to_cart = display_add_to_cart or item.order_max > 0
         else:
             for var in item.available_variations:
+                var.description = str(var.description)
+                for recv, resp in item_description.send(sender=event, item=item, variation=var):
+                    if resp:
+                        var.description += ("<br/>" if var.description else "") + resp
+
                 if voucher and (voucher.allow_ignore_quota or voucher.block_quota):
                     var.cached_availability = (
                         Quota.AVAILABILITY_OK, voucher.max_usages - voucher.redeemed