无法使此自定义日志记录适配器示例正常工作

Question

我一直在这里查看与上下文日志记录相关的示例： Logging Cookbook

但是，我无法使以下示例正常工作。该示例应演示自定义适配器的使用，并继续如下操作：

# Here is a simple example:

class CustomAdapter(logging.LoggerAdapter):
"""
This example adapter expects the passed in dict-like object to have a
'connid' key, whose value in brackets is prepended to the log message.
"""
def process(self, msg, kwargs):
    return '[%s] %s' % (self.extra['connid'], msg), kwargs

# which you can use like this:

logger = logging.getLogger(__name__)
adapter = CustomAdapter(logger, {'connid': some_conn_id})

# Then any events that you log to the adapter will have the value of some_conn_id prepended to the log messages.

但是，无论我尝试了什么，总是会遇到一个关键错误：

logger = logging.getLogger(__name__)

syslog = logging.StreamHandler()
formatter = logging.Formatter('%(asctime)s <<<CONTEXT: %(my_context)s>>> : %(message)s')
syslog.setFormatter(formatter)

adapter = CustomAdapter(logger, {'my_context': '1956'})

logger.setLevel(logging.INFO)
logger.addHandler(syslog)

logger.info('The sky is so blue', {'my_context': '6642'})


Traceback (most recent call last):
File "/Users/me/apps/Darwin64/python2.7/lib/python2.7/logging/__init__.py", line 859, in emit
msg = self.format(record)
File "/Users/me/apps/Darwin64/python2.7/lib/python2.7/logging/__init__.py", line 732, in format
return fmt.format(record)
File "/Users/me/apps/Darwin64/python2.7/lib/python2.7/logging/__init__.py", line 474, in format
s = self._fmt % record.__dict__
KeyError: 'my_context'
Logged from file myApp.py, line 62

我做错了什么？

---解决方案：EDIT_01 ---

我已经更改了代码，以便使用adapter.info('The sky is so blue', {'my_context': '6642'})。而且有效。但是，我必须my_context从格式化程序中删除。但是，使用下面的代码，该my_context位是硬编码的，无论我通过记录器传递什么，它始终会显示初始值。有没有办法将某些值传递给适配器？

logger = logging.getLogger(__name__)
syslog = logging.StreamHandler()
formatter = logging.Formatter('%(asctime)s %(message)s')
syslog.setFormatter(formatter)
logger.addHandler(syslog)
adapter = CustomAdapter(logger, {'my_context': '1956'})
logger.setLevel(logging.INFO)
adapter.info('The sky is so blue', {'my_context': '6642'})

这将始终生成：

2016-09-13 11:33:18,404 [1956] The sky is so blue

即使我们正在6642通过记录器。

Answer 1

您必须使用适配器记录日志，而不是记录器。尝试这个：

import logging

class CustomAdapter(logging.LoggerAdapter):
    def process(self, msg, kwargs):
        # use my_context from kwargs or the default given on instantiation
        my_context = kwargs.pop('my_context', self.extra['my_context'])
        return '[%s] %s' % (my_context, msg), kwargs

logger = logging.getLogger(__name__)
syslog = logging.StreamHandler()
formatter = logging.Formatter('%(asctime)s %(message)s')
syslog.setFormatter(formatter)
logger.addHandler(syslog)
adapter = CustomAdapter(logger, {'my_context': '1956'})
logger.setLevel(logging.INFO)

adapter.info('The sky is so blue', my_context='6642')
adapter.info('The sky is so blue')

输出：

2016-09-13 14:49:28,539 [6642] The sky is so blue
2016-09-13 14:49:28,540 [1956] The sky is so blue