python logging:自定义Python LogRecord抛出错误

Question

我试图使用python日志记录模块创建一个自定义日志文件,记录其他信息,如主机名,并将其添加到我的数据库.下面是我为此创建的类,Handler部分工作得很好,但是现在我添加了一个自定义LogRecord类,它会抛出这个错误:

/src/lib/__init__.py", line 31, in __init__
logging.LogRecord.__init__(self, *args, **kwargs)
exceptions.TypeError: __init__() takes at most 9 arguments (10 given)

以下是我执行它的方式

logging.setLoggerClass(MyLogger)

log = logging.getLogger('testing')
log.addHandler(MyLogHandler())
d = {'host': '192.168.0.1'}
log.warn('Hi', d)    

以下是课程.它显然与*args,**kwargs有关,但是当我看它时,*args是空的,而**kwargs只包含d上面指定的变量.我不明白这个问题.

class MyLogRecord(logging.LogRecord):
    def __init__(self, *args, **kwargs):
        logging.LogRecord.__init__(self, *args, **kwargs) //THIS IS THE LINE IT DIES ON
        self.host = 'localhost'

class MyLogFormatter(logging.Formatter):

    def __init__(self, fmt, datefmt=None, host=None):
        logging.Formatter.__init__(self, fmt, datefmt)
        self.host = host

    def format(self, record):
        return logging.Formatter.format(record)

class MyLogger(logging.getLoggerClass()):
    def makeRecord(self, *args, **kwargs):
        return MyLogRecord(*args, **kwargs)

class MyLogHandler(logging.Handler): # Inherit from logging.Handler
    def __init__(self):
        # run the regular Handler __init__
        logging.Handler.__init__(self)
        # Our custom argument
        self.mongo = MongoLogger()

    def setupCustomLogger(self, name, this_host):
        formatter = MyLogFormatter(fmt='%(asctime)s - %(levelname)s - %(module)s - %(message)s - %(host)s')

        handler = logging.StreamHandler()
        handler.setFormatter(formatter)

        logger = logging.getLogger(name)
        logger.setLevel(logging.DEBUG)
        logger.addHandler(handler)
        return logger

    def emit(self, record):
        # record.message is the log message
        self.mongo.log(record)


class MongoLogger(object):

'''Logs messages to a MongoDB fh_admin log collection.'''
def log(self, message):
    #@todo write log to DB
    print message

Answer 1

错误告诉你到底出了什么问题; 你用太多的参数调用构造函数.要了解我的意思,请查看在默认实现中通常如何构建日志记录makeRecord:

def makeRecord(self, name, level, fn, lno, msg, args, exc_info, func=None, extra=None):
    """
    A factory method which can be overridden in subclasses to create
    specialized LogRecords.
    """
    rv = LogRecord(name, level, fn, lno, msg, args, exc_info, func)
    if extra is not None:
        for key in extra:
            if (key in ["message", "asctime"]) or (key in rv.__dict__):
                raise KeyError("Attempt to overwrite %r in LogRecord" % key)
            rv.__dict__[key] = extra[key]
    return rv

请注意makeRecord如何获取一个extra不直接传递给它的参数LogRecord？另一方面,你将它直接传递给了LogRecord.__init__,这导致了错误.

从这里,你有两个选择; 你可以提供更完整的实现makeRecord,或者你可以尝试使用这个LoggerAdapter类,它可以帮助你用更少的代码实现相同的目标.

这是一个例子:

# Common log info to be added to all logs reported with `log_adapter`
context = {'host': 'localhost'}

log = logging.getLogger('testing')
log.addHandler(logging.StreamHandler())
d = {'host': '192.168.0.1'}

log_adapter = logging.LoggerAdapter(log, context)
log_adapter.warning('Hi', d)

如果您需要在每次记录某些内容时计算"host"的值(例如),您可以创建context一个类似于字典的类的实例.像这样:

class LogContext(object):

    def __getitem__(self, key):
        if key == 'host':
            return 'localhost'
        raise KeyError(key)

    def __iter__(self):
        return iter(['host'])

log_adapter = logging.LoggerAdapter(log, LogContext())
log_adapter.warning('Hi', d)

有一点需要注意LoggingAdapter,它显然没有将所有便捷的快捷方式功能定义为普通的Logger类.这就是我调用warning方法的原因,而不是warn你上面所说的.

有关LoggingAdapter日志的更多信息和添加上下文可以在python文档中找到.

注意 - 我没有包括MyLogHandler,MyLogFormatter或MongoLogger在我的示例中,因为它们与问题/错误无关.