如何在Python日志格式字符串中添加自定义字段? [英] How do I add custom field to Python log format string?

问题描述

我当前的格式字符串是:

My current format string is:

formatter = logging.Formatter('%(asctime)s : %(message)s')

我想添加一个名为app_name的新字段，在包含该格式化程序的每个脚本中，该字段将具有不同的值.

and I want to add a new field called app_name and which will have a different value in each script that contains this formatter.

import logging
formatter = logging.Formatter('%(asctime)s %(app_name)s : %(message)s')
syslog.setFormatter(formatter)
logger.addHandler(syslog)

但是我不确定如何将app_name值传递给记录器以内插到格式字符串中.我显然可以使它显示在日志消息中，但是每次都通过它，但这很麻烦.

But I'm not sure how to pass that app_name value to the logger to interpolate into the format string. I can obviously get it to appear in the log message but passing it each time but this is messy.

我尝试过:

logging.info('Log message', app_name='myapp')
logging.info('Log message', {'app_name', 'myapp'})
logging.info('Log message', 'myapp')

，但无济于事.

推荐答案

您可以使用 LoggerAdapter ，因此您不必在每次记录调用时都传递额外的信息:

You could use a LoggerAdapter so you don't have to pass the extra info with every logging call:

import logging
extra = {'app_name':'Super App'}

logger = logging.getLogger(__name__)
syslog = logging.StreamHandler()
formatter = logging.Formatter('%(asctime)s %(app_name)s : %(message)s')
syslog.setFormatter(formatter)
logger.setLevel(logging.INFO)
logger.addHandler(syslog)

logger = logging.LoggerAdapter(logger, extra)
logger.info('The sky is so blue')

日志(类似)

2013-07-09 17:39:33,596 Super App : The sky is so blue

---

过滤器也可以用于添加上下文信息.

---

Filters can also be used to add contextual information.

import logging

class AppFilter(logging.Filter):
    def filter(self, record):
        record.app_name = 'Super App'
        return True

logger = logging.getLogger(__name__)
logger.addFilter(AppFilter())
syslog = logging.StreamHandler()
formatter = logging.Formatter('%(asctime)s %(app_name)s : %(message)s')
syslog.setFormatter(formatter)
logger.setLevel(logging.INFO)
logger.addHandler(syslog)

logger.info('The sky is so blue')

产生类似的日志记录.

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