Add view for ToS

aleksis/apps/paweljong/predicates.py

@@ -38,3 +38,9 @@ def is_organiser(user: User, obj: Union[Event, EventRegistration]) -> bool:
 def is_event_published(user: User, obj: EventRegistration) -> bool:
     """Predicate which checks if the event is published."""
     return obj.published
+
+
+@predicate
+def is_participant(user: User, obj: Event) -> bool:
+    """Predicate which checks if the user is member of the event."""
+    return user.person in obj.linked_group.members.all()