NuclearPeon NuclearPeon - 1 month ago 9
Ajax Question

How do I get POST "data" variable in python3.x without using CGI?

When I attempt to call

in a
cgi script, I get the following error:

[Traceback: error in module x on line y]:
File "/usr/lib64/python3.3/", line 553, in __init__
File "/usr/lib64/python3.3/", line 709, in read_single
File "/usr/lib64/python3.3/", line 731, in read_binary
TypeError: must be str, not bytes

How do I get my POST
variable from an ajax call?

Example ajax call:

function (param) {
type: "POST",
url: "/cgi-bin/",
data: JSON.stringify({"foo": "bar"}),
contentType: "application/json; charset=utf-8",
dataType: "json",
success: function (result) {
alert("Success " + result);
error: function () {


According to

"There are also some special cases in the stdlib where strings are 
very confusing. The cgi.FieldStorage module which WSGI applications are 
sometimes still using for form data parsing is now treating QUERY_STRING 
as surrogate escaping, but instead of using utf-8 as charset for the URLs 
(as browsers) it treats it as the encoding returned by 
locale.getpreferredencoding(). I have no idea why it would do that, but 
it's incorrect. As workaround I recommend not using cgi.FieldStorage for 
query string parsing."

The solution to this problem is to use to read in POST data parameters. However please note that your cgi application can hang if it expects to read in something and nothing is sent. This is solved by reading in the number of bytes that is found in the HTTP Header:

#!/usr/bin/env python3
import os, sys, json
# To get data in a native python dictionary, use json.loads
if data:
    print(list(json.loads(data).keys()]) # Prints out keys of json

# (You need to wrap the .keys() in list() because it would otherwise return 
#  "dict_keys([a, b, c])" instead of [a, b, c])

You can read more about the internals of CGI here: