Trying to parse JSON in Python. ValueError: Expecting property name
Question:
I am trying to parse a JSON object into a Python dict. I’ve never done this before. When I googled this particular error, (What is wrong with the first char?), other posts have said that the string being loaded is not actually a JSON string. I’m pretty sure this is, though.
In this case, eval() works fine, but I’m wondering if there is a more appropriate way?
Note: This string comes directly from Twitter, via ptt tools.
>>> import json
>>> line = '{u'follow_request_sent': False, u'profile_use_background_image': True,
u'default_profile_image': False,
u'verified': False, u'profile_sidebar_fill_color': u'DDEEF6',
u'profile_text_color': u'333333', u'listed_count': 0}'
>>> json.loads(line)
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
File "/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/json/__init__.py", line 326, in loads
return _default_decoder.decode(s)
File "/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 "/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)
Answers:
That’s definitely not JSON – not as printed above anyhow. It’s already been parsed into a Python object – JSON would have false, not False, and wouldn’t show strings as u for unicode (all JSON strings are unicode). Are you sure you’re not getting your json string turned into a Python object for free somewhere in the chain already, and thus loading it into json.loads() is obviously wrong because in fact it’s not a string?
Sometimes you can have this error because your string values are not well recognized by python. As an example: I’ve spent quite a lot of time searching for the origin of this kind of error. Here is what I found.
Sometimes a language recognizes a kind of quotes and not another one:
btw, to parse a string in to json in JavaScript all quotes have to be in the ‘ format
to parse a string into json in JavaScript all quotes have to be in the ” format which is not really logic.
Hopefully you can use the replace function. For Python:
json.loads(s.replace("'", '"'));
Hope it will save you the time I’ve spent hunting this bug!
I got this error when I had a hanging comma at the end of a list of properties. Because of the comma it was expecting another property name but there was none.
Make sure that your JSON file does not have lines start with // (which wrongfully supposed to comments!). I have the same ValueError message and it’s gone after I removed the // from my file.
I am trying to parse a JSON object into a Python dict. I’ve never done this before. When I googled this particular error, (What is wrong with the first char?), other posts have said that the string being loaded is not actually a JSON string. I’m pretty sure this is, though.
In this case, eval() works fine, but I’m wondering if there is a more appropriate way?
Note: This string comes directly from Twitter, via ptt tools.
>>> import json
>>> line = '{u'follow_request_sent': False, u'profile_use_background_image': True,
u'default_profile_image': False,
u'verified': False, u'profile_sidebar_fill_color': u'DDEEF6',
u'profile_text_color': u'333333', u'listed_count': 0}'
>>> json.loads(line)
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
File "/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/json/__init__.py", line 326, in loads
return _default_decoder.decode(s)
File "/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 "/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)
That’s definitely not JSON – not as printed above anyhow. It’s already been parsed into a Python object – JSON would have false, not False, and wouldn’t show strings as u for unicode (all JSON strings are unicode). Are you sure you’re not getting your json string turned into a Python object for free somewhere in the chain already, and thus loading it into json.loads() is obviously wrong because in fact it’s not a string?
Sometimes you can have this error because your string values are not well recognized by python. As an example: I’ve spent quite a lot of time searching for the origin of this kind of error. Here is what I found.
Sometimes a language recognizes a kind of quotes and not another one:
btw, to parse a string in to json in JavaScript all quotes have to be in the ‘ format
to parse a string into json in JavaScript all quotes have to be in the ” format which is not really logic.
Hopefully you can use the replace function. For Python:
json.loads(s.replace("'", '"'));
Hope it will save you the time I’ve spent hunting this bug!
I got this error when I had a hanging comma at the end of a list of properties. Because of the comma it was expecting another property name but there was none.
Make sure that your JSON file does not have lines start with // (which wrongfully supposed to comments!). I have the same ValueError message and it’s gone after I removed the // from my file.