python - 使用 python 请求模块时的 LocationValueError

Question

我一直在使用请求包与网络交互，过去没有遇到任何问题。最近在使用我大约一周未使用的脚本时，在执行例行 requests.get() 调用时遇到以下错误:

LocationValueError: No host specified.

背景研究

经过大量谷歌搜索 python requests LocationValueError、python requests no host error 和 python urllib3 LocationValueError 的各种排列(根据堆栈跟踪错误是由请求在下面使用的 urllib3 引发的)我只设法找到隐藏在 urllib3 文档中的信息:

exception urllib3.exceptions.LocationValueError

Raised when there is something wrong with a given URL input.

我尝试过的

认为我的请求包版本可能有问题，因为这可以说是请求包中使用的最基本的调用之一，我做了以下操作:

• 重新安装请求
• 创建虚拟环境并使用 pip 安装请求
• 来自源的已安装请求
• 显式安装 urllib3
• 从源代码安装 python 3.4 然后尝试(我现在使用 python3.5)

在所有情况下，我都使用以下代码来查看请求是否仍在抛出 LocationValueError:

import requests
address = 'http://www.google.com/'    
requests.get(address)

这在过去一直有效。我检查了另一台计算机(一台 ubuntu 笔记本电脑)，它在那里工作，这让我认为这个问题是我的计算机特有的。

问题的堆栈跟踪

这是我在使用安装在 virtualenv 中的请求和 python3.4 时得到的堆栈跟踪。

In [5]: import requests

In [6]: requests.get('http://www.google.com/')
---------------------------------------------------------------------------
LocationValueError                        Traceback (most recent call last)
 in ()
----> 1 requests.get('http://www.google.com/')

/home/michael/Documents/my_test_env/lib/python3.4/site-packages/requests/api.py in get(url, params, **kwargs)
     67 
     68     kwargs.setdefault('allow_redirects', True)
---> 69     return request('get', url, params=params, **kwargs)
     70 
     71 

/home/michael/Documents/my_test_env/lib/python3.4/site-packages/requests/api.py in request(method, url, **kwargs)
     48 
     49     session = sessions.Session()
---> 50     response = session.request(method=method, url=url, **kwargs)
     51     # By explicitly closing the session, we avoid leaving sockets open which
     52     # can trigger a ResourceWarning in some cases, and look like a memory leak

/home/michael/Documents/my_test_env/lib/python3.4/site-packages/requests/sessions.py in request(self, method, url, params, data, headers, cookies, files, auth, timeout, allow_redirects, proxies, hooks, stream, verify, cert, json)
    466         }
    467         send_kwargs.update(settings)
--> 468         resp = self.send(prep, **send_kwargs)
    469 
    470         return resp

/home/michael/Documents/my_test_env/lib/python3.4/site-packages/requests/sessions.py in send(self, request, **kwargs)
    574 
    575         # Send the request
--> 576         r = adapter.send(request, **kwargs)
    577 
    578         # Total elapsed time of the request (approximately)

/home/michael/Documents/my_test_env/lib/python3.4/site-packages/requests/adapters.py in send(self, request, stream, timeout, verify, cert, proxies)
    335         """
    336 
--> 337         conn = self.get_connection(request.url, proxies)
    338 
    339         self.cert_verify(conn, request.url, verify, cert)

/home/michael/Documents/my_test_env/lib/python3.4/site-packages/requests/adapters.py in get_connection(self, url, proxies)
    247             proxy = prepend_scheme_if_needed(proxy, 'http')
    248             proxy_manager = self.proxy_manager_for(proxy)
--> 249             conn = proxy_manager.connection_from_url(url)
    250         else:
    251             # Only scheme should be lower case

/home/michael/Documents/my_test_env/lib/python3.4/site-packages/requests/packages/urllib3/poolmanager.py in connection_from_url(self, url)
    137         """
    138         u = parse_url(url)
--> 139         return self.connection_from_host(u.host, port=u.port, scheme=u.scheme)
    140 
    141     def urlopen(self, method, url, redirect=True, **kw):

/home/michael/Documents/my_test_env/lib/python3.4/site-packages/requests/packages/urllib3/poolmanager.py in connection_from_host(self, host, port, scheme)
    246 
    247         return super(ProxyManager, self).connection_from_host(
--> 248             self.proxy.host, self.proxy.port, self.proxy.scheme)
    249 
    250     def _set_proxy_headers(self, url, headers=None):

/home/michael/Documents/my_test_env/lib/python3.4/site-packages/requests/packages/urllib3/poolmanager.py in connection_from_host(self, host, port, scheme)
    108 
    109         if not host:
--> 110             raise LocationValueError("No host specified.")
    111 
    112         scheme = scheme or 'http'

LocationValueError: No host specified.

如果有人可以帮助解释错误原因或为我指出正确的方向，我们将不胜感激。当我使用 request.Session 对象获取扩展 session 的页面时，也会发生此问题。

Answer 1

对我来说，问题是我被请求的 url 重定向到 Location: https//，这可能是无效的，但 urllib3 无法处理。