使用requests.raise_for_status()时，如何捕获404并输出自定义错误信息？

问题 #

之前使用requests库时，404错误未被正确捕获，而是被传递给其他异常。引入raise_for_status()方法后，虽然能触发HTTPError终止代码，但无法打印自定义错误信息，仅输出栈跟踪。

原代码 #

try:
    response = requests.request(
        request_type, url, headers=headers, data=payload
    )
    response.raise_for_status()
except requests.ConnectionError as ce:
    logger.info(
        f"""It appears you may need to check
        your internet connection - {ce}"""
    )
except requests.exceptions.HTTPError as he:

    if response.raise_for_status() == 404:
        logger.info(
            f"""We seem to be having an issue
            with your request - {he.response}"""
        )
        logger.info(f"request - {he.request}")
return response

404错误触发的栈跟踪 #

Traceback (most recent call last):
  File "/home/user/projects/project_code/url_help/url_help.py", line 51, in connect_to_url
    response.raise_for_status()
  File "/home/user/projects/project_code/env/lib/python3.10/site-packages/requests/models.py", line 1021, in raise_for_status
    raise HTTPError(http_error_msg, response=self)
requests.exceptions.HTTPError: 404 Client Error: Not Found for url: https://api-url.com/item/v3/companies/8951507/persons?page=1&pageSize=10

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "/home/user/projects/project_code/main.py", line 99, in <module>
    main(args)
  File "/home/user/projects/project_code/main.py", line 50, in main
    ).get_employees_from_company_id(PAGE_SIZE, COMPANY_ID)
  File "/home/user/projects/project_code/employee_dict/employee_dict.py", line 109, in get_employees_from_company_id
    response = Url.connect_to_url(
  File "/home/user/projects/project_code/url_help/url_help.py", line 60, in connect_to_url
    if response.raise_for_status() == 404:
  File "/home/user/projects/project_code/env/lib/python3.10/site-packages/requests/models.py", line 1021, in raise_for_status
    raise HTTPError(http_error_msg, response=self)
requests.exceptions.HTTPError: 404 Client Error: Not Found for url: https://api-url.com/item/v3/companies/8951507/persons?page=1&pageSize=10

需要修改代码以正常打印自定义错误信息，并保留错误代码记录。

解决方案 #

核心问题是except块中再次调用response.raise_for_status()——该方法仅会抛出异常，不会返回状态码，因此这行代码会再次触发HTTPError，导致栈跟踪覆盖自定义日志逻辑。

修正后的代码 #

try:
    response = requests.request(
        request_type, url, headers=headers, data=payload
    )
    response.raise_for_status()
except requests.ConnectionError as ce:
    logger.info(
        f"It appears you may need to check your internet connection - {ce}"
    )
except requests.exceptions.HTTPError as he:
    # 通过捕获的异常对象获取响应状态码
    if he.response.status_code == 404:
        logger.info(
            f"We seem to be having an issue with your request - {he.response}"
        )
        logger.info(f"request - {he.request}")
    # 可选：处理其他HTTP错误场景
    else:
        logger.info(f"HTTP Error occurred: {he}")
return response

关键说明 #

1. raise_for_status()无返回值，仅在状态码非2xx时抛出HTTPError，不能用于判断状态码。
2. 捕获HTTPError后，可通过he.response.status_code直接获取响应状态码，或直接使用response.status_code（response对象在except块中仍可访问）。
3. 修正后，404错误会触发自定义日志输出，不会再次抛出未处理的异常。

内容的提问来源于stack exchange，提问作者Ryan