一旦读取，就无法读取urllib错误消息 [英] Cannot read urllib error message once it is read()

问题描述

我的问题是python urllib错误对象的错误处理。我无法读取错误消息，但仍将其完整保留在错误对象中，以备日后使用。

My problem is with error handling of the python urllib error object. I am unable to read the error message while still keeping it intact in the error object, for it to be consumed later.

response = urllib.request.urlopen(request) # request that will raise an error
response.read()
response.read() # is empty now
# Also tried seek(0), that does not work either.

这就是我打算如何使用它，但是当异常冒出来时， .read（）第二次为空。

So this how I intend to use it, but when the Exception bubbles up, the.read() second time is empty.

try:
    response = urllib.request.urlopen(request)
except urllib.error.HTTPError as err:
    self.log.exception(err.read())
    raise err

我尝试制作err对象的深层副本

I tried making a deepcopy of the err object,

import copy
try:
    response = urllib.request.urlopen(request)
except urllib.error.HTTPError as err:
    err_obj_copy = copy.deepcopy(err)
    self.log.exception(
        "Method:{}\n"
        "URL:{}\n"
        "Data:{}\n"
        "Details:{}\n"
        "Headers:{}".format(method, url, data, err_obj_copy.read(), headers))
    raise err

但副本无法进行深度复制并引发错误-
TypeError：__init __（）缺少5个必需的位置参数备注： url， code， msg， hdrs和 fp 。

but copy is unable to make a deepcopy and throws an error - TypeError: __init__() missing 5 required positional arguments: 'url', 'code', 'msg', 'hdrs', and 'fp'.

如何阅读错误消息，同时仍将其完整保留在对象中？

How do I read the error message, while still keeping it intact in the object?

我确实知道如何使用请求来做到这一点，但是我受制于旧版代码，需要使其与 urllib

I do know how to do it using requests, but I am stuck with legacy code and need to make it work with urllib

推荐答案

这就是我所做的。

首次读取错误时，请将其保存到这样的变量中： msg = response.read（）。解码（'utf8'）。然后，您可以使用该消息创建一个新的 HTTPError 实例，并将其传播。

When reading the error for the first time, save it to a variable like this: msg = response.read().decode('utf8'). You can then create a new HTTPError instance, with the message, and propagate it.

resp = urllib.request.urlopen(request)
msg = resp.read().decode('utf8')
self.log.exception(msg)
raise HTTPError(resp.url, resp.code, resp.reason, resp.headers, io.BytesIO(bytes(msg, 'utf8')))

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