import json import os try: # Python 3 from urllib.parse import parse_qs except ImportError: # Python 2 from urlparse import parse_qs def application(environ, start_response): ret = { 'FileExists': False, } d = parse_qs(environ['QUERY_STRING']) ret['FileExists'] = os.path.exists(d.get('path')[0]) out = json.dumps(ret) start_response( '200', [ ('Content-Type', 'application/json'), ('Content-Length', str(len(out))), ], ) return out.encode('utf-8')