Parsing a json output string

Question

I am new to Python, How to convert this to a json string? I like to get the first line of the commitMessage in below output(op) ? thanks in advance

>>> op = subprocess.Popen('ssh -p 29999 server-name.com gerrit query --commit-message --format=JSON Ib3856dcf0826942787c3d5a076eb6888dae9k2be', shell=True, stdout=subprocess.PIPE, cwd='../').communicate()
>>>
>>> op
('{"project":"mtt/proprietary/fg","branch":"master","id":"Ib3856dcf0826942787c3d5a076eb6888dae9k2be","number":"1857599","subject":"store Gain","owner":{"name":"owner1","email":"[email protected]","username":"user1"},"url":"https://server-name.com/1857599","commitMessage":"my commit message\\n\\nChange-Id: Ib949999d3f4d94299993d5a076eb681c4aaaa2be\\n","createdOn":1478281199,"lastUpdated":1478732989,"sortKey":"0041150d001ad179","open":false,"status":"MERGED"}\n{"type":"stats","rowCount":1,"runTimeMilliseconds":4}\n', None)
>>> js = json.loads(op)
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/usr/lib/python2.7/json/__init__.py", line 338, in loads
    return _default_decoder.decode(s)
  File "/usr/lib/python2.7/json/decoder.py", line 366, in decode
    obj, end = self.raw_decode(s, idx=_w(s, 0).end())
TypeError: expected string or buffer

op is a tuple, perhaps you meant json.loads(op[0])

AChampion
– AChampion

2016-11-16 17:37:11 +00:00
Commented Nov 16, 2016 at 17:37 — AChampion
– AChampion, Commented Nov 16, 2016 at 17:37
Try this json.loads(json.dumps(op))

Daniyal Syed
– Daniyal Syed

2016-11-16 18:14:55 +00:00
Commented Nov 16, 2016 at 18:14 — Daniyal Syed
– Daniyal Syed, Commented Nov 16, 2016 at 18:14

Alexey Guseynov · Accepted Answer · 2016-11-16 17:37:16Z

4

Processes have two standard output streams: stdout and stderr. One for regular output and other for errors. communicate returns a tuple with two elements: first is stdout and second is stderr. You need the first:

json.loads(op[0])

answered Nov 16, 2016 at 17:37

Alexey Guseynov

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5 Comments

rodee Over a year ago

thanks, I get error

raise ValueError(errmsg("Extra data", s, end, len(s))) ValueError: Extra data: line 2 column 1 - line 3 column 1 (char 597 - 651)

any idea?

Alexey Guseynov Over a year ago

Your json is not valid. Comma is missing before {"type":"stats",

rodee Over a year ago

yes \n{"type":"stats","rowCount":1,"runTimeMilliseconds":2}\n is the second item in the gerrit query output, checking how to make gerrit query stop printing that, or can I make python to ignore it?

rodee Over a year ago

op = op[0].split('\n')[0] did it, :), dirty ?

Alexey Guseynov Over a year ago

No, not dirty. You need the first line and this code does exactly that.

Guillaume · Accepted Answer · 2016-11-16 17:37:23Z

1

Your op variable returned from subprocess is not a string, it is a tuple of 2 elements. Just do: js = json.loads(op[0]) instead, to parse the first element, which is the json string you are attempting to parse

answered Nov 16, 2016 at 17:37

Guillaume

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