From b4e092600dc2cfd5326a373b4b9fd757a5d8a61a Mon Sep 17 00:00:00 2001
From: Grey Li <withlihui@gmail.com>
Date: Wed, 2 May 2018 17:08:31 +0800
Subject: [PATCH] Check whether exist registered routes

---
 flask/cli.py | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/flask/cli.py b/flask/cli.py
index 635abb13..efc1733e 100644
--- a/flask/cli.py
+++ b/flask/cli.py
@@ -825,6 +825,10 @@ def routes_command(sort, all_methods):
     """Show all registered routes with endpoints and methods."""
 
     rules = list(current_app.url_map.iter_rules())
+    if not rules:
+        click.echo('No routes were registered.')
+        return
+
     ignored_methods = set(() if all_methods else ('HEAD', 'OPTIONS'))
 
     if sort in ('endpoint', 'rule'):