added messaging

rowers/views.py

@@ -3081,6 +3081,9 @@ def otwrankings_view(request,theuser=0,
         '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)
     powerdf.sort_values(['Delta','CP'],ascending=[1,0],inplace=True)