added calculation on db values

matecnt/views.py

@@ -101,12 +101,16 @@ def checkout(request):
 
     count = int(request.REQUEST.get('count', 1))
     drink_data = get_drink(drink)
+    total = drink_data.prize * count
+    drinker = get_user(user)
+    drinker.credit -= total
+    drinker.save()
 
     ctx = {
         'heading': 'Codes scanned: user=%r drink=%r amount=%s' % (user, drink, count),
-        'drinker': get_user(user),
+        'drinker': drinker,
         'drink': drink_data,
-        'total': drink_data.prize * count,
+        'total': total,
     }
     return render(request, 'checkout.html', ctx)
 
@@ -122,9 +126,13 @@ def charge(request):
     except KeyError as ex:
         return HttpResponse(status=400)
 
+    drinker = get_user(user)
+    drinker.credit += charge
+    drinker.save()
+
     ctx = {
         'heading': 'Charging: user=%r amount=%s' % (user, charge),
-        'drinker': get_user(user),
+        'drinker': drinker,
         'amount': charge,
     }
     return render(request, 'charge.html', ctx)