回溯当我使用urllib2时，得到HTTP500错误

Question

我的代码如下所示，但是当它运行时会抛出一个错误。

search_request = urllib2.Request(url,data=tmp_file_name,headers={'X-Requested-With':'WoMenShi888XMLHttpRequestWin'})
#print search_request.get_method()
search_response = urllib2.urlopen(search_request)
html_data = search_response.read()

错误是：

Traceback (most recent call last):
  File "xx_tmp.py", line 83, in <module>
    print hello_lfi()
  File "xx_tmp.py", line 69, in hello_lfi
    search_response = urllib2.urlopen(search_request)
  File "D:\Python27\lib\urllib2.py", line 126, in urlopen
    return _opener.open(url, data, timeout)
  File "D:\Python27\lib\urllib2.py", line 406, in open
    response = meth(req, response)
  File "D:\Python27\lib\urllib2.py", line 519, in http_response
    'http', request, response, code, msg, hdrs)
  File "D:\Python27\lib\urllib2.py", line 444, in error
    return self._call_chain(*args)
  File "D:\Python27\lib\urllib2.py", line 378, in _call_chain
    result = func(*args)
  File "D:\Python27\lib\urllib2.py", line 527, in http_error_defau
    raise HTTPError(req.get_full_url(), code, msg, hdrs, fp)
urllib2.HTTPError: HTTP Error 500: Internal Server Error

我不知道该怎么修？我的意思是，当错误发生时，我的代码如何继续工作？

当我尝试使用

       try:
                search_response = urllib2.urlopen(search_request)
            except urllib2.HTTPError:
                pass

新错误

UnboundLocalError: local variable 'search_response' referenced before assignment

我使用

global search_response

并且有错误

NameError: global name 'search_response' is not defined

Answer 1

你可以捕获异常，这将防止你的程序如此“突然”地停止：

try:
  search_response = urllib2.urlopen(search_request)
except urllib2.HTTPError:
  print 'There was an error with the request'

如果您想继续，您可以简单地：

try:
  search_response = urllib2.urlopen(search_request)
except urllib2.HTTPError:
  pass

这将允许您的程序继续运行；但是您的另一条语句html_data = search_response.read()不会给出预期的结果。要永久地解决这个问题，您需要调试您的请求以了解其失败的原因；这并不是Python所特有的。

Answer 2

当我试图向我的GAE Python服务器发送一个大型post请求时，我也遇到了同样的错误。结果是服务器抛出了这个错误，因为我试图将收到的POST字符串写入db.StringProperty()。我将其更改为db.TextProperty()，它不再抛出错误。

来源：Overcome appengine 500 byte string limit in python? consider text