def renders(col_name):
 def wrap(f):
  if (not hasattr(f, '_col_name')):
   f._col_name = col_name
  return f
 return wrap

def renders ( col_name ) : def wrap ( f ) : if ( not hasattr ( f , '_col_name' ) ) : f . _col_name = col_name return f return wrap
use this decorator to map your custom model properties to actual model db properties .