Python日志记录-向自定义格式化程序添加附加的最终字段

Question

我为Logger提供了以下格式化程序类，用于我们公司的libary中：

import json
import logging
from typing import Optional


class CustomFormatter(logging.Formatter):

    def __init__(
        self,
        fmt: Optional[str] = "%(asctime)s",
        datefmt: Optional[str] = None,
        style: Optional[str] = "%",
        confidentiality: Optional[str] = "C3",
    ) -> None:
        self.confidentiality = confidentiality
        super().__init__(fmt=fmt, datefmt=datefmt, style=style)

    def formatMessage(self, record: logging.LogRecord, *args, **kwargs) -> str:
        super().formatMessage(record)
        return json.dumps(
            {
                "asctime": record.asctime,
                "level": record.levelname,
                "name": record.name,
                "message": record.message,
                "timeMillis": int(record.created * 1000),
                "pathName": record.pathname,
                "funcName": record.funcName,
                "lineNumber": record.lineno,
                "confidentiality": self.confidentiality,
            }
        )

我尝试添加这样的自定义字段：

old_factory = logging.getLogRecordFactory()

def record_factory(*args, **kwargs):
    record = old_factory(*args, **kwargs)
    record.custom_attribute = "my-attr"
    return record

logging.setLogRecordFactory(record_factory)

logger = logging.getLogger()
logger.setLevel(logging.DEBUG)
logger_handler = logging.StreamHandler()
logger_handler.setFormatter(CustomFormatter())
logger.addHandler(logger_handler)

logger.info("Ich bin ein Test")

结果：

{"asctime": "2022-06-29 10:40:22,869", "level": "INFO", "name": "root", "message": "test", "timeMillis": 1656492022869, "pathName": "C:\\Users\\xcg5847\\Desktop\\loggingnew\\test.py", "funcName": "<module>", "lineNumber": 15, "
confidentiality": "C3"}

这是没有增加的。我猜问题在于，格式化程序总是返回相同的json对象，而这本身是不可扩展的，就其构建方式而言。

这就是我想要的：

{"asctime": "2022-06-29 10:40:22,869", "level": "INFO", "name": "root", "message": "test", "timeMillis": 1656492022869, "pathName": "C:\\Users\\xcg5847\\Desktop\\loggingnew\\test.py", "funcName": "<module>", "lineNumber": 15, "
confidentiality": "C3", "custom_attribute": "my-attr"}

的重要性:理想情况下，这样的工作方式是：

logger.info("test", extra={"custom_attribute": "my-attr"}

Answer 1

您所面临的问题是，您成功地将属性添加到记录中，但是格式化程序却忽略了它。除了更改或替换正在使用的CustomFormatter之外，没有其他办法。可能的解决方案如下所示：

class CustomFormatterExtra(CustomFormatter):
    custom_name = 'custom_attribute'

    def formatMessage(self, record, *args, **kwargs):
        json_str = super().formatMessage(record, *args, **kwargs)
        if hasattr(record, self.custom_name):
            json_dict = json.loads(json_str)
            json_dict[self.custom_name] = getattr(record, self.custom_name)
            json_str = json.dumps(json_dict)
        return json_str


logger = logging.getLogger()
logger.setLevel(logging.DEBUG)
logger_handler = logging.StreamHandler()
logger_handler.setFormatter(CustomFormatterExtra())
logger.addHandler(logger_handler)

logger.info("Ich bin ein Test", extra={'custom_attribute':123})
CustomFormatterExtra.custom_name = 'different_attribute'
logger.info("Ich bin ein Test", extra={'different_attribute':123})

注意，这不需要定制的LogRecord工厂。extra param做的和你的一模一样。