forbidden saving ad hoc metrics as favorite chart

rowers/views.py

@@ -8413,11 +8413,20 @@ def workout_flexchart3_view(request,*args,**kwargs):
             workstrokesonly = request.POST['workstrokesonlysave']
             reststrokes = not workstrokesonly
 	    r = getrower(request.user)
-            f = FavoriteChart(user=r,xparam=xparam,
+            try:
+                r = metrics.yaxmaxima[xparam]
+                if yparam1 is not None:
+                    r = metrics.yaxmaxima[yparam1]
+                if yparam2 is not None:
+                    r = metrics.yaxmaxima[yparam2]
+                f = FavoriteChart(user=r,xparam=xparam,
                               yparam1=yparam1,yparam2=yparam2,
                               plottype=plottype,workouttype=workouttype,
                               reststrokes=reststrokes)
-            f.save()
+                f.save()
+                
+            except KeyError:
+                messages.error(request,'We cannot save the ad hoc metrics in a favorite chart')
 
     if request.method == 'POST' and 'workstrokesonly' in request.POST:
 	workstrokesonly = request.POST['workstrokesonly']