将日志消息格式化为树

Question

我想让python日志输出以对应于记录树的树的形式.看看例子.

让我们说我们有一个代码:

import logging

logger_a = logging.getLogger("a")
logger_a_b = logging.getLogger("a.b")
logger_a_b_c = logging.getLogger("a.b.c")
# ...


logger_a.debug("One")

logger_a_b.warning("two")
logger_a_b.warning("three")

logger_a_b_c.critical("Four")

logger_a_b.warning("Five")

输出应该是这样的:

<--"a"
   |   DEBUG: One
   |
   o<--"a.b"
   |   | WARNING: Two
   |   | WARNING: Three
   |   |
   |   o<--"a.b.c"
   |       | CRITICAL: Four   
   |       |
   |   | WARNING: Five

我可以手动为每个日志编写格式化程序,但它没有解决插入类似o < - "ab"的问题,我宁愿通过日志记录结构自动计算偏移量.

有一个名为日志记录树的模块.它打印日志记录布局.我想要的是以大致相同的方式打印日志消息.

你知道任何图书馆,方法吗？

Answer 1

根据您的示例，我创建了一个自定义Formatter来处理树。

import logging

# custom tree formatter
class TreeFormatter(logging.Formatter):
    formatPrefix = {} # map loggername, formatPrefix

    def format(self, record):
        s = ""
        # first time this name is encountered: create the prefix and print the name
        if not record.name in self.formatPrefix: 
            f = self.getFormatPrefix(record)
            s += "%s \"%s\"\n" % (f, record.name)

        # print the actual message
        s += "%s %s: %s" % (self.formatPrefix[record.name], record.levelname, record.msg) 
        return s


    # create the format prefix for the given package name 
    # (stored in self.formatPrefix[record.name])
    # and return the first line to print
    def getFormatPrefix(self, record):
        depth = record.name.count(".")
        self.formatPrefix[record.name] = "   |" * (depth+1)

        if depth == 0:
            return "<--"

        return "%so<--" % ( ("   |" * depth)[:-1])

然后您可以使用它来创建第一级记录器（此处为 a）。其余代码不变。

这是一个例子：

# use this to create the first level logger
def createTreeLogger(name, level=logging.DEBUG):
    logger = logging.getLogger(name)
    logger.setLevel(level)
    ch = logging.StreamHandler()
    ch.setLevel(level)
    ch.setFormatter(TreeFormatter())
    logger.addHandler(ch)
    return logger


if __name__ == '__main__':

    logger_a = createTreeLogger("a") # first level: use createLogger
    # then create your loggers as always
    logger_a_b = logging.getLogger("a.b") 
    logger_a_b_c = logging.getLogger("a.b.c")


    logger_a.debug("One")

    logger_a_b.warning("two")
    logger_a_b.warning("three")

    logger_a_b_c.critical("Four")

    logger_a_b.warning("Five")
    logger_a.warning("Six")

好处是日志记录包内部将自动对子包（ab、abc）使用相同的处理程序。因此，通过运行此代码，您将得到：

<-- "a"
   | DEBUG: One
   o<-- "a.b"
   |   | WARNING: two
   |   | WARNING: three
   |   o<-- "a.b.c"
   |   |   | CRITICAL: Four
   |   | WARNING: Five
   | WARNING: Six

一个缺点是，如果您有多个包层次结构，日志会变得混乱。但该TreeFormatter课程很容易根据您的需求进行调整。