我得到错误期望值:第1行第1列(字符0)时试图解码JSON。

我用于API调用的URL在浏览器中工作正常,但在通过curl请求完成时给出了这个错误。下面是我用于curl请求的代码。

错误发生在返回simplejson.loads(response_json)时

response_json = self.web_fetch(url)
response_json = response_json.decode('utf-8')
return json.loads(response_json)


def web_fetch(self, url):
    buffer = StringIO()
    curl = pycurl.Curl()
    curl.setopt(curl.URL, url)
    curl.setopt(curl.TIMEOUT, self.timeout)
    curl.setopt(curl.WRITEFUNCTION, buffer.write)
    curl.perform()
    curl.close()
    response = buffer.getvalue().strip()
    return response

回溯:

File "/Users/nab/Desktop/myenv2/lib/python2.7/site-packages/django/core/handlers/base.py" in get_response
  111.                         response = callback(request, *callback_args, **callback_kwargs)
File "/Users/nab/Desktop/pricestore/pricemodels/views.py" in view_category
  620.     apicall=api.API().search_parts(category_id= str(categoryofpart.api_id), manufacturer = manufacturer, filter = filters, start=(catpage-1)*20, limit=20, sort_by='[["mpn","asc"]]')
File "/Users/nab/Desktop/pricestore/pricemodels/api.py" in search_parts
  176.         return simplejson.loads(response_json)
File "/Users/nab/Desktop/myenv2/lib/python2.7/site-packages/simplejson/__init__.py" in loads
  455.         return _default_decoder.decode(s)
File "/Users/nab/Desktop/myenv2/lib/python2.7/site-packages/simplejson/decoder.py" in decode
  374.         obj, end = self.raw_decode(s)
File "/Users/nab/Desktop/myenv2/lib/python2.7/site-packages/simplejson/decoder.py" in raw_decode
  393.         return self.scan_once(s, idx=_w(s, idx).end())

Exception Type: JSONDecodeError at /pricemodels/2/dir/
Exception Value: Expecting value: line 1 column 1 (char 0)

当前回答

你的代码产生了一个空的响应体,你会想要检查它或者捕获异常。有可能服务器响应了204 No Content响应,或者返回了一个非200范围的状态码(404 Not Found等)。检查这个。

注意:

没有必要使用simplejson库,Python中包含了与json模块相同的库。 没有必要解码从UTF8到unicode的响应,simplejson / json .loads()方法可以原生处理UTF8编码的数据。 pycurl的API非常古老。除非您对使用它有特定的要求,否则还有更好的选择。

无论是请求还是httpx都提供了更友好的api,包括JSON支持。如果可以,把你的电话换成:

import requests

response = requests.get(url)
response.raise_for_status()  # raises exception when not a 2xx response
if response.status_code != 204:
    return response.json()

当然,这并不能保护您免受不符合HTTP标准的URL的影响;当可能使用任意url时,检查服务器是否打算通过检查Content-Type头来给你JSON,并捕捉异常:

if (
    response.status_code != 204 and
    response.headers["content-type"].strip().startswith("application/json")
):
    try:
        return response.json()
    except ValueError:
        # decide how to handle a server that's misbehaving to this extent

其他回答

很多时候,这是因为你试图解析的字符串是空的:

>>> import json
>>> x = json.loads("")
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/usr/local/Cellar/python/3.7.3/Frameworks/Python.framework/Versions/3.7/lib/python3.7/json/__init__.py", line 348, in loads
    return _default_decoder.decode(s)
  File "/usr/local/Cellar/python/3.7.3/Frameworks/Python.framework/Versions/3.7/lib/python3.7/json/decoder.py", line 337, in decode
    obj, end = self.raw_decode(s, idx=_w(s, 0).end())
  File "/usr/local/Cellar/python/3.7.3/Frameworks/Python.framework/Versions/3.7/lib/python3.7/json/decoder.py", line 355, in raw_decode
    raise JSONDecodeError("Expecting value", s, err.value) from None
json.decoder.JSONDecodeError: Expecting value: line 1 column 1 (char 0)

你可以通过事先检查json_string是否为空来补救:

import json

if json_string:
    x = json.loads(json_string)
else:
    # Your code/logic here 
    x = {}

我遇到了同样的问题,当打印出从json文件中打开的json字符串时,发现json字符串以''开头,通过做一些研究,这是因为文件默认是用UTF-8解码的,通过将编码改为UTF-8 -sig,标记被剥离,加载json没有问题:

open('test.json', encoding='utf-8-sig')

检查文件的编码格式,读取文件时使用相应的编码格式。它会解决你的问题。

with open("AB.json", encoding='utf-8', errors='ignore') as json_data:
     data = json.load(json_data, strict=False)

对我来说,这是服务器响应的东西,而不是200,响应不是json格式的。我最终在json解析之前这样做:

# this is the https request for data in json format
response_json = requests.get() 

# only proceed if I have a 200 response which is saved in status_code
if (response_json.status_code == 200):  
     response = response_json.json() #converting from json to dictionary using json library

如果你使用header并且有"Accept-Encoding": "gzip, deflate, br",安装brotli库pip install。你不需要将brotli导入py文件。