Question

I have been trying to use JSON to store settings for a program. I can’t seem to get Python 2.6 ‘s JSON Decoder to decode multi-line JSON strings…

Here is example input:

.settings file:
"""
{\
  'user':'username',\
  'password':'passwd',\
}\
"""

I have tried a couple other syntaxes for this file, which I will specify below (with the traceback they cause).

My python code for reading the file in is

import json
settings_text = open(".settings", "r").read()
settings = json.loads(settings_text)

The Traceback for this is:

Traceback (most recent call last):
  File "json_test.py", line 4, in <module>
    print json.loads(text)
  File "/System/Library/Frameworks/Python.framework/Versions/2.6/lib/python2.6/json/__init__.py", line 307, in loads
    return _default_decoder.decode(s)
  File "/System/Library/Frameworks/Python.framework/Versions/2.6/lib/python2.6/json/decoder.py", line 322, in decode
    raise ValueError(errmsg("Extra data", s, end, len(s)))
ValueError: Extra data: line 1 column 2 - line 7 column 1 (char 2 - 41)

I assume the “Extra data” is the triple-quote.

Here are the other syntaxes I have tried for the .settings file, with their respective Tracebacks:

"{\
  'user':'username',\
  'pass':'passwd'\
}"

Traceback (most recent call last):
  File "json_test.py", line 4, in <module>
    print json.loads(text)
  File "/System/Library/Frameworks/Python.framework/Versions/2.6/lib/python2.6/json/__init__.py", line 307, in loads
    return _default_decoder.decode(s)
  File "/System/Library/Frameworks/Python.framework/Versions/2.6/lib/python2.6/json/decoder.py", line 319, in decode
    obj, end = self.raw_decode(s, idx=_w(s, 0).end())
  File "/System/Library/Frameworks/Python.framework/Versions/2.6/lib/python2.6/json/decoder.py", line 336, in raw_decode
    obj, end = self._scanner.iterscan(s, **kw).next()
  File "/System/Library/Frameworks/Python.framework/Versions/2.6/lib/python2.6/json/scanner.py", line 55, in iterscan
    rval, next_pos = action(m, context)
  File "/System/Library/Frameworks/Python.framework/Versions/2.6/lib/python2.6/json/decoder.py", line 155, in JSONString
    return scanstring(match.string, match.end(), encoding, strict)
ValueError: Invalid \escape: line 1 column 2 (char 2)



'{\
  "user":"username",\
  "pass":"passwd",\
}'

Traceback (most recent call last):
  File "json_test.py", line 4, in <module>
    print json.loads(text)
  File "/System/Library/Frameworks/Python.framework/Versions/2.6/lib/python2.6/json/__init__.py", line 307, in loads
    return _default_decoder.decode(s)
  File "/System/Library/Frameworks/Python.framework/Versions/2.6/lib/python2.6/json/decoder.py", line 319, in decode
    obj, end = self.raw_decode(s, idx=_w(s, 0).end())
  File "/System/Library/Frameworks/Python.framework/Versions/2.6/lib/python2.6/json/decoder.py", line 338, in raw_decode
    raise ValueError("No JSON object could be decoded")
ValueError: No JSON object could be decoded

If I put the settings all on one line, it decodes fine.

Answer 1

Get rid of all of the backslashes and all of the “Pythonic” quoting in the settings file. Works fine if the file is just:

{
  "user":"username",
  "password":"passwd"
}

Note also that JSON strings are quoted with double quotes, not single quotes. See JSON spec here:

http://www.json.org/