用额外的信息提高HTTPError

问题描述

| 如果它是404，我想用一个额外的信息捕获一个：0ѭ：

try:
    data = urlopen(url)
except HTTPError,e:  # Python 2.5 Syntax
    if e.code == 404:
        raise HTTPError(\'data not found on remote\')
    else:
        raise

但这不起作用，因为

HTTPError

的init接受多个参数，这些参数未记录。它确实起作用，它将丢失回溯信息和原始消息。我也试过

if e.code == 404:
    e.message = \'data not found on remote: %s\' % e.message
raise

但这只是在没有额外信息的情况下重新引发了异常。我该怎么办？     

解决方法

        您只需要使用

e.msg

而不是

e.message

。剧本：

from urllib2 import urlopen,HTTPError

url = \'http://www.red-dove.com/frob\'

try:
    data = urlopen(url)
except HTTPError,e:  # Python 2.5 syntax
    if e.code == 404:
        e.msg = \'data not found on remote: %s\' % e.msg
    raise

版画

Traceback (most recent call last):
  File \"c:\\temp\\test404.py\",line 6,in <module>
    data = urlopen(url)
  File \"C:\\Python\\Lib\\urllib2.py\",line 124,in urlopen
    return _opener.open(url,data)
  File \"C:\\Python\\Lib\\urllib2.py\",line 387,in open
    response = meth(req,response)
  File \"C:\\Python\\Lib\\urllib2.py\",line 498,in http_response
    \'http\',request,response,code,msg,hdrs)
  File \"C:\\Python\\Lib\\urllib2.py\",line 425,in error
    return self._call_chain(*args)
  File \"C:\\Python\\Lib\\urllib2.py\",line 360,in _call_chain
    result = func(*args)
  File \"C:\\Python\\Lib\\urllib2.py\",line 506,in http_error_default
    raise HTTPError(req.get_full_url(),hdrs,fp)
urllib2.HTTPError: HTTP Error 404: data not found on remote: Not Found

您当然可以使用随附的try / except进行整理：

from urllib2 import urlopen,HTTPError

url = \'http://www.red-dove.com/frob\'

try:
    try:
        data = urlopen(url)
    except HTTPError,e:  # Python 2.5 syntax
        if e.code == 404:
            e.msg = \'data not found on remote: %s\' % e.msg
        raise
except HTTPError,e:
    print e

简单地打印

HTTP Error 404: data not found on remote: Not Found

该异常具有所有原始细节：

e.__dict__

看起来像

{\'__iter__\': <bound method _fileobject.__iter__ of <socket._fileobject object at   0x00AF2EF0>>,\'code\': 404,\'fileno\': <bound method _fileobject.fileno of <socket._fileobject object at 0x00AF2EF0>>,\'fp\': <addinfourl at 12003088 whose fp = <socket._fileobject object at 0x00AF2EF0>>,\'hdrs\': <httplib.HTTPMessage instance at 0x00B727B0>,\'headers\': <httplib.HTTPMessage instance at 0x00B727B0>,\'msg\': \'data not found on remote: Not Found\',\'next\': <bound method _fileobject.next of <socket._fileobject object at 0x00AF2EF0>>,\'read\': <bound method _fileobject.read of <socket._fileobject object at 0x00AF2EF0>>,\'readline\': <bound method _fileobject.readline of <socket._fileobject object at 0x00AF2EF0>>,\'readlines\': <bound method _fileobject.readlines of <socket._fileobject object at 0x00AF2EF0>>,\'url\': \'http://www.red-dove.com/frob\'}

    ,        HTTPError已经包含了您需要的所有信息，您可以像这样简单地重新提出它

raise HTTPError(e.url,e.code,\"your message.\",e.hdrs,e.fp)