callback template implementaion

app/app.py

@@ -650,15 +650,15 @@ async def rebindLostDevices():
 async def userStateChangeCallback(user, state, prevState = None):
   reply = None
   if ('HTTP_CLIENT' in app.config) and (user in app.cache['devicemap']):
-    url = await db.fetch_one(query='SELECT url FROM callback_urls WHERE device = :device',
+    row = await db.fetch_one(query='SELECT url FROM callback_urls WHERE device = :device',
                              values={'device': app.cache['devicemap'][user]})
-    app.logger.warning(pformat(url))
-    reply = await app.config['HTTP_CLIENT'].post(url,
-                                                 json={'user': user,
-                                                       'state': state,
-                                                       'prev_state':prevState})
+    if row is not None:
+      reply = await app.config['HTTP_CLIENT'].post(row['url'],
+                                                   json={'user': user,
+                                                         'state': state,
+                                                         'prev_state':prevState})
 
-    app.logger.warning('{} changed state to: {}'.format(user, state))
+  app.logger.warning('{} changed state to: {}'.format(user, state))
   return reply
 
 def getUserStateCombined(user):