在python中如何重试一次异常 [英] How to retry just once on exception in python

问题描述

我可能接近这个错误的方式，但是我有一个POST请求出来：

I might be approaching this the wrong way, but I've got a POST request going out:

response = requests.post(full_url, json.dumps(data))

哪些可能会由于一些原因而失败，一些与数据有关，一些是临时故障，由于设计不当的端点可能会因为相同的错误而返回（服务器使用无效数据做不可预测的事情）。为了抓住这些暂时的失败，让别人通过，我认为最好的方法是重试一次，然后如果再次出现错误，继续。我相信我可以做一个嵌套的尝试/除了，但它似乎是糟糕的做法（如果我想在放弃之前尝试两次？）

Which could potentially fail for a number of reasons, some being related to the data, some being temporary failures, which due to a poorly designed endpoint may well return as the same error (server does unpredictable things with invalid data). To catch these temporary failures and let others pass I thought the best way to go about this would be to retry once and then continue if the error is raised again. I believe I could do it with a nested try/except, but it seems like bad practice to me (what if I want to try twice before giving up?)

解决方案是：

try:
    response = requests.post(full_url, json.dumps(data))
except RequestException:
    try:
        response = requests.post(full_url, json.dumps(data))
    except:
        continue

有更好的方法吗？另外还有一种更好的方法来处理可能出现的HTTP响应错误？

Is there a better way to do this? Alternately is there a better way in general to deal with potentially faulty HTTP responses?

推荐答案

for _ in range(2):
    try:
        response = requests.post(full_url, json.dumps(data))
        break
    except RequestException:
        pass
else:
    raise # both tries failed

如果您需要一个功能这个：

If you need a function for this:

def multiple_tries(func, times, exceptions):
    for _ in range(times):
        try:
            return func()
        except Exception as e:
            if not isinstance(e, exceptions):
                raise # reraises unexpected exceptions 
    raise # reraises if attempts are unsuccessful

使用如下：

func = lambda:requests.post(full_url, json.dumps(data))
response = multiple_tries(func, 2, RequestException)

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