rewrite topics routes to include id

app/routes/topics.py

@@ -10,11 +10,21 @@ def all_topics():
     topic_list = Topics.get_list()
     return render_template('topics/topics.html', topics=topic_list)
 
-@bp.get('/<slug>/')
-def topic(slug):
-    topic = Topics.find({'slug': slug})
+@bp.get('/<int:topic_id>/')
+def topic_by_id(topic_id):
+    topic = Topics.find({'id': topic_id})
     if not topic:
         abort(404)
+    return redirect(url_for('.topic', topic_id=topic_id, slug=topic.slug, **request.args))
+
+@bp.get('/<int:topic_id>/<slug>/')
+def topic(topic_id, slug):
+    topic = Topics.find({'id': topic_id})
+    if not topic:
+        abort(404)
+    if topic.slug != slug:
+        return redirect(url_for('.topic', topic_id=topic_id, slug=topic.slug, **request.args))
+
     sort_by = request.args.get('sort_by', default=session.get('sort_by', default='activity'))
     PER_PAGE = 10
     threads_count = Threads.count({'topic_id': topic.id})
@@ -25,6 +35,6 @@ def topic(slug):
         abort(404)
     return render_template('topics/topic.html', topic=topic, threads=topic.get_threads(PER_PAGE, page, sort_by), sort_by=sort_by, page=page, page_count=page_count)
 
-@bp.get('/<slug>/feed.atom')
-def feed(slug):
+@bp.get('/<int:topic_id>/feed.atom/')
+def feed(topic_id):
     return 'stub'