Python os.environ会引发关键错误吗？

Question

我正在访问一个脚本中的环境变量os.environ.get,它正在抛出一个KeyError.它不会从Python提示符中抛出错误.它在OS X 10.11.6上运行,并且是Python 2.7.10.

到底是怎么回事？

$ python score.py
Traceback (most recent call last):
  File "score.py", line 4, in <module>
    setup_logging()
  File "/score/log.py", line 29, in setup_logging
    config = get_config()
  File "/score/log.py", line 11, in get_config
    environment = os.environ.get('NODE_ENV')
  File "/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/UserDict.py", line 23, in __getitem__
    raise KeyError(key)
KeyError: 'NODE_ENV'
$ python -c "import os; os.environ.get('NODE_ENV')"
$

根据要求,这是源代码 score.py

from __future__ import print_function

from log import get_logger, setup_logging
setup_logging()
log = get_logger('score')

这是 log.py

import json
import os
import sys

from iron_worker import IronWorker
from logbook import Logger, Processor, NestedSetup, StderrHandler, SyslogHandler

IRON_IO_TASK_ID = IronWorker.task_id()

def get_config():
  environment = os.environ.get('NODE_ENV')
  if environment == 'production':
    filename = '../config/config-production.json'
  elif environment == 'integration':
    filename = '../config/config-integration.json'
  else:
    filename = '../config/config-dev.json'

  with open(filename) as f:
    return json.load(f)

def setup_logging():
  # This defines a remote Syslog handler
  # This will include the TASK ID, if defined
  app_name = 'scoreworker'
  if IRON_IO_TASK_ID:
    app_name += '-' + IRON_IO_TASK_ID

  config = get_config()

  default_log_handler = NestedSetup([
    StderrHandler(),
    SyslogHandler(
      app_name,
      address = (config['host'], config['port']),
      level = 'ERROR',
      bubble = True
    )
  ])
  default_log_handler.push_application()

def get_logger(name):
  return Logger(name)

Answer 1

试试跑步:

find . -name \*.pyc -delete

删除.pyc文件.

研究你的问题我遇到了这个问题,一个用户遇到了同样的事情:.get()似乎提出了一个问题KeyError.在这种情况下,根据这个接受的答案,它是由一个.pyc文件引起的,该文件包含dict通过密钥(即mydict['potentially_nonexistent_key'])访问值的代码,而回溯显示了使用的更新.py文件中的代码.get().我从来没有听说过这样的情况,其中从回溯引用当前代码的.py文件,而是显示了一个过时的引发错误.pyc的文件,但它似乎在Python的历史上已经发生至少一次...

这是一个很长的镜头,但值得一试,我想.

Answer 2

我在设置环境变量而不导出它时遇到了类似的错误。所以如果你这样做：

me@host:/# NODE_ENV=foo

你会得到这个：

me@host:/# python3
Python 3.8.2 (default, Apr 27 2020, 15:53:34) 
[GCC 9.3.0] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> import os
>>> node_env = os.environ['NODE_ENV']
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
File "/usr/lib/python3.8/os.py", line 675, in __getitem__
raise KeyError(key) from None
KeyError: 'NODE_ENV'
>>>

但如果你这样做：

me@host:/# NODE_ENV=foo
me@host:/# export NODE_ENV

有用：

me@host:/# python3
Python 3.8.2 (default, Apr 27 2020, 15:53:34) 
[GCC 9.3.0] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> import os
>>> node_env = os.environ['NODE_ENV']
>>> print(node_env)
foo
>>>