Invalidate markup cache on ticket edit

Fixes #168

todosrht/blueprints/ticket.py

@@ -5,6 +5,7 @@ from srht.database import db
 from srht.flask import loginrequired
 from srht.validation import Validation
 from todosrht.access import get_tracker, get_ticket
+from todosrht.filters import invalidate_markup_cache
 from todosrht.search import find_usernames
 from todosrht.tickets import add_comment, mark_seen, assign, unassign
 from todosrht.types import Event, EventType
@@ -199,6 +200,8 @@ def ticket_edit_POST(owner, name, ticket_id):
     ticket.description = desc
     db.session.commit()
 
+    invalidate_markup_cache(ticket)
+
     return redirect(ticket_url(ticket))
 
 @ticket.route("/<owner>/<name>/<int:ticket_id>/add_label", methods=["POST"])

todosrht/filters.py

@@ -67,6 +67,11 @@ def render_comment(comment):
 def render_ticket_description(ticket):
     return render_markup(ticket.tracker, ticket.description)
 
+def invalidate_markup_cache(obj):
+    class_name = obj.__class__.__name__
+    key = f"todo.sr.ht:cache_rendered_markup:{class_name}:{obj.id}"
+    redis.delete(key)
+
 def label_badge(label, cls="", remove_from_ticket=None):
     """Return HTML markup rendering a label badge.