Add new signal nav_item

src/pretix/control/views/item.py

@@ -33,7 +33,7 @@ from pretix.control.forms.item import (
 from pretix.control.permissions import (
     EventPermissionRequiredMixin, event_permission_required,
 )
-from pretix.control.signals import item_forms
+from pretix.control.signals import item_forms, nav_item
 
 from . import ChartContainingView, CreateView, PaginationMixin, UpdateView
 
@@ -782,6 +782,18 @@ class ItemDetailMixin(SingleObjectMixin):
     model = Item
     context_object_name = 'item'
 
+    def get_context_data(self, **kwargs):
+        ctx = super().get_context_data(**kwargs)
+        nav = sorted(
+            sum(
+                (list(a[1]) for a in nav_item.send(self.request.event, request=self.request, item=self.get_object())),
+                []
+            ),
+            key=lambda r: str(r['label'])
+        )
+        ctx['extra_nav'] = nav
+        return ctx
+
     def get_object(self, queryset=None) -> Item:
         try:
             if not hasattr(self, 'object') or not self.object: