Django admin "save and view on site" button

Besides adding button in change_form template, you would want to override response_change method of ModelAdmin (and response_add).

Something like this should work:

def response_change(self, request, obj):
  res = super(MyModelAdmin, self).response_change(request, obj)
  if "_preview" in request.POST:
    return HttpResponseRedirect('preview-url-here')
  else:
    return res