added messaging

rowers/views.py

@@ -3080,6 +3080,9 @@ def otwrankings_view(request,theuser=0,
         'Delta':delta,
         'CP':cpvalue,
         })
+
+    if powerdf.empty:
+        messages.info(request,'Your calculations are running in the background. Please reload this page.')
     
     powerdf = powerdf[powerdf['CP']>0]
     powerdf.dropna(axis=0,inplace=True)