simplejson.loads() get Invalid \escape: 'x'

Question

I am learning how to use simplejson to decode JSON file. But I suffered the "invalid \escape" error. Here is the code

import simplejson as json

def main():
    json.loads(r'{"test":"\x27"}')

if __name__ == '__main__':
    main()

And here is the error message

Traceback (most recent call last):
  File "hello_world.py", line 7, in <module>
    main()
  File "hello_world.py", line 4, in main
    json.loads(r'{"test":"\x27"}')
  File "C:\Users\zhangkai\python\simplejson\__init__.py", line 307, in loads
    return _default_decoder.decode(s)
  File "C:\Users\zhangkai\python\simplejson\decoder.py", line 335, in decode
    obj, end = self.raw_decode(s, idx=_w(s, 0).end())
  File "C:\Users\zhangkai\python\simplejson\decoder.py", line 351, in raw_decode

    obj, end = self.scan_once(s, idx)
  File "C:\Users\zhangkai\python\simplejson\scanner.py", line 36, in _scan_once
    return parse_object((string, idx + 1), encoding, strict, _scan_once, object_
hook)
  File "C:\Users\zhangkai\python\simplejson\decoder.py", line 185, in JSONObject

    value, end = scan_once(s, end)
  File "C:\Users\zhangkai\python\simplejson\scanner.py", line 34, in _scan_once
    return parse_string(string, idx + 1, encoding, strict)
  File "C:\Users\zhangkai\python\simplejson\decoder.py", line 114, in py_scanstr
ing
    raise ValueError(errmsg(msg, s, end))
ValueError: Invalid \escape: 'x': line 1 column 10 (char 10)

I think json parser is supposed to recognize the escape. So I want to know what is wrong, and what should I do.

Answer 1

try python-cjson

import cjson
s = cjson.encode({'abc':123,'def':'xyz'})
print 'json: %s - %s' % (type(s), s)
s = cjson.decode(s)
print '%s - %s' % (type(s), s)

Answer 2

JSON has no hex escape (\xNN) like some languages (including JavaScript) and notations do, details here. It has a unicode escape, \uNNNN where NNNN is four hex digits, but no \x hex escape.

Answer 3

This is expected behavior from a parser as that JSON is invalid; within a string a slash may be followed only by ", \, /, b, f, n, r, t or u (which must then be followed by 4 hex characters). An x is not allowed. See the spec at http://json.org/