ValueError:使用ast.literal_eval的格式错误的字符串 [英] ValueError: malformed string using ast.literal_eval
问题描述
我正在做一个循环以获取json api,这是我循环中的内容:
I'm doing a loop to get json api, here is what I have in my loop:
response_item = requests.request('GET',url_item,params=None,verify=False)
response_item = json.loads(response_item.text)
response_item = ast.literal_eval(json.dumps(response_item, ensure_ascii=False).encode('utf8'))
我扫描了45000个json对象,每次迭代都会生成"url_item"变量.每个对象都是相同的,到达7064时会得到类似7000对象的错误,并且出现以下错误:
I scan around 45000 json objects, I generate "url_item" variable for each iteration. Each object is the same, I can get something like 7000 object and I have the following error when I reach the 7064th:
Traceback (most recent call last):
File "C:\Python27\tools\api_item.py", line 47, in <module>
response_item = ast.literal_eval(json.dumps(response_item, ensure_ascii=False).encode('utf8'))
File "C:\Python27\lib\ast.py", line 80, in literal_eval
return _convert(node_or_string)
File "C:\Python27\lib\ast.py", line 63, in _convert
in zip(node.keys, node.values))
File "C:\Python27\lib\ast.py", line 62, in <genexpr>
return dict((_convert(k), _convert(v)) for k, v
File "C:\Python27\lib\ast.py", line 63, in _convert
in zip(node.keys, node.values))
File "C:\Python27\lib\ast.py", line 62, in <genexpr>
return dict((_convert(k), _convert(v)) for k, v
File "C:\Python27\lib\ast.py", line 79, in _convert
raise ValueError('malformed string')
ValueError: malformed string
我曾经打印第二和第三"response_item".当然,在这种情况下,由于我之前有错误,所以第三个没有显示,这是我在json.load之后要打印的内容:
I used to print the second and third "response_item". Of course in this case the third one isn't displayed since I have the error just before, here what I have for the print after the json.load:
{u'restrictions': [], u'name': u'Sac \xe0 dos de base', u'level': 0, u'rarity': u'Basic', u'vendor_value': 11, u'details': {u'no_sell_or_sort': False, u'size': 20}, u'game_types': [u'Activity', u'Wvw', u'Dungeon', u'Pve'], u'flags': [u'NoSell', u'SoulbindOnAcquire', u'SoulBindOnUse'], u'icon': u'https://render.guildwars2.com/file/80E36806385691D4C0910817EF2A6C2006AEE353/61755.png', u'type': u'Bag', u'id': 8932, u'description': u'Un sac de 20 emplacements pour les personnages d\xe9butants.'}
在此之前得到的所有物品都具有相同的类型,相同的格式,除了7064号以外,我没有任何错误!
Every item I get before this one has the same type, same format, and I don't have any error except for the 7064th !
谢谢您的帮助!
推荐答案
您应不对JSON数据使用ast.literal_eval()
. JSON和Python文字可能看起来就像是同一件事,但是它们却不一样.
You should not use ast.literal_eval()
on JSON data. JSON and Python literals may look like the same thing, but they are very much not.
在这种情况下,您的数据包含一个布尔标志,在JSON中设置为false
.适当的Python布尔值使用标题大小写,因此False
:
In this case, your data contains a boolean flag, set to false
in JSON. A proper Python boolean uses title-case, so False
:
>>> import json, ast
>>> s = '{"no_sell_or_sort": false, "size": 20}'
>>> json.loads(s)
{u'no_sell_or_sort': False, u'size': 20}
>>> ast.literal_eval(s)
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
File "/Users/mj/Development/Library/buildout.python/parts/opt/lib/python2.7/ast.py", line 80, in literal_eval
return _convert(node_or_string)
File "/Users/mj/Development/Library/buildout.python/parts/opt/lib/python2.7/ast.py", line 63, in _convert
in zip(node.keys, node.values))
File "/Users/mj/Development/Library/buildout.python/parts/opt/lib/python2.7/ast.py", line 62, in <genexpr>
return dict((_convert(k), _convert(v)) for k, v
File "/Users/mj/Development/Library/buildout.python/parts/opt/lib/python2.7/ast.py", line 79, in _convert
raise ValueError('malformed string')
ValueError: malformed string
其他区别包括使用null
代替None
,以及Python 2的Unicode转义序列看起来像纯(字节)字符串,在转义非BMP代码点.
Other differences include using null
instead of None
, and Unicode escape sequences in what to Python 2 looks like a plain (bytes) string, using UTF-16 surrogates when escaping non-BMP codepoints.
使用json.loads()
而不是ast.literal_eval()
加载数据.它不仅可以正确处理JSON,而且还更快.
Load your data with json.loads()
, not ast.literal_eval()
. Not only will it handle proper JSON just fine, it is also faster.
在您的情况下,您似乎正在使用json.dumps()
,然后尝试再次使用ast.literal_eval()
加载数据.该步骤不需要,您已经已经拥有一个Python对象.
In your case, it appears you are using json.dumps()
then try to load the data again with ast.literal_eval()
. There is no need for that step, you already had a Python object.
换句话说,一行:
response_item = ast.literal_eval(json.dumps(response_item, ensure_ascii=False).encode('utf8'))
最好是多余的,最坏的情况是非常非常错误的.将response_item
重新编码为JSON字符串不会产生可解释为Python文字的内容.
is redundant at best, and very, very wrong, at worst. Re-encoding response_item
to a JSON string does not produce something that can be interpreted as a Python literal.
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