vinni_pux vinni_pux - 5 months ago 32
JSON Question

python json.loads doesn't work

It's my code.
I've been tyring to figure out how to load JSON objects in Python.

def do_POST(self):
length = int(self.headers['Content-Length'])
decData = str(self.rfile.read(length))
print decData, type(decData)
"{'name' : 'journal2'}" <type 'str'>
postData = json.loads(decData)
print postData, type(postData)
#{'name' : 'journal2'} <type 'unicode'>
postData = json.loads(postData)
print postData, type(postData)
# Error: Expecting property name enclosed in double quotes


Where am i going wrong?

error code jscript

var data = "{'name':'journal2'}";
var http_request = new XMLHttpRequest();
http_request.open( "post", url, true );
http_request.setRequestHeader('Content-Type', 'application/json');
http_request.send(data);


true code jscript

var data = '{"name":"journal2"}';
var http_request = new XMLHttpRequest();
http_request.open( "post", url, true );
http_request.setRequestHeader('Content-Type', 'application/json');
http_request.send(JSON.stringify(data));


true code python

def do_POST(self):
length = int(self.headers['Content-Length'])
decData = self.rfile.read(length)
postData = json.loads(decData)
postData = json.loads(postData)


I apologize for my English. Thanks to all

Answer

Your JSON data is enclosed in extra quotes making it a JSON string, and the data contained within that string is not JSON.

Print repr(decData) instead, you'll get:

'"{\'name\' : \'journal2\'}"'

and the JSON library is correctly interpreting that as one string with the literal contents {'name' : 'journal2'}. If you stripped the outer quotes, the contained characters are not valid JSON, because JSON strings must always be enclosed in double quotes.

For all the json module is concerned, decData could just as well have contained "This is not JSON" and postData would have been set to u'This is not JSON'.

>>> import json
>>> decData = '''"{'name' : 'journal2'}"'''
>>> json.loads(decData)
u"{'name' : 'journal2'}"
>>> json.loads(json.loads(decData))
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/opt/local/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/json/__init__.py", line 326, in loads
    return _default_decoder.decode(s)
  File "/opt/local/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/json/decoder.py", line 366, in decode
    obj, end = self.raw_decode(s, idx=_w(s, 0).end())
  File "/opt/local/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/json/decoder.py", line 382, in raw_decode
    obj, end = self.scan_once(s, idx)
ValueError: Expecting property name: line 1 column 1 (char 1)

Fix whatever is producing this string, your view is fine, it's the input that is broken.

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