将记录器消息存储在字符串中

Question

我想将所有中间日志消息（警告，信息，错误）存储到python中的字符串，最后在程序结束时，将所有内容显示为控制台的报告。

我试图按照http://opensourcehacker.com/2011/02/23/temporarily-capturing-python-logging-output-to-a-string-buffer/中列出的步骤但是没有成功。

有人能告诉我一个简短，干净的方法吗？

这就是我现在尝试过的：

    log  = logging.getLogger('basic_logger')
    log.setLevel(logging.DEBUG)
    report=""

            memory_handler=logging.handlers.MemoryHandler(1024*20,logging.ERROR,report)
memory_handler.setLevel(logging.DEBUG)
log.addHandler(memory_handler)

log.info("hello world")
memory_handler.flush()
print "report:",report

Answer 1

它可以像记录到StringIO对象一样简单：

import logging
try:
    from cStringIO import StringIO      # Python 2
except ImportError:
    from io import StringIO

log_stream = StringIO()    
logging.basicConfig(stream=log_stream, level=logging.INFO)

logging.info('hello world')
logging.warning('be careful!')
logging.debug("you won't see this")
logging.error('you will see this')
logging.critical('critical is logged too!')

print(log_stream.getvalue())

产量

INFO:root:hello world
WARNING:root:be careful!
ERROR:root:you will see this
CRITICAL:root:critical is logged too!

---

如果您只想在WARN，INFO和ERROR级别记录这些消息，则可以使用过滤器进行记录。下面的LevelFilter检查每个日志记录的级别no，仅允许所需级别的记录：

import logging
try:
    from cStringIO import StringIO      # Python 2
except ImportError:
    from io import StringIO

class LevelFilter(logging.Filter):
    def __init__(self, levels):
        self.levels = levels

    def filter(self, record):
        return record.levelno in self.levels

log_stream = StringIO()    
logging.basicConfig(stream=log_stream, level=logging.NOTSET)
logging.getLogger().addFilter(LevelFilter((logging.INFO, logging.WARNING, logging.ERROR)))

logging.info('hello world')
logging.warning('be careful!')
logging.debug("you won't see this")
logging.error('you will see this')
logging.critical('critical is no longer logged!')

print(log_stream.getvalue())

产量

INFO:root:hello world
WARNING:root:be careful!
ERROR:root:you will see this

Answer 2

您也可以编写自己的流类。正如https://docs.python.org/2/library/logging.handlers.html所说，只有writeand和flushare用于流媒体。

例：

import logging

class LogStream(object):
    def __init__(self):
        self.logs = ''

    def write(self, str):
        self.logs += str

    def flush(self):
        pass

    def __str__(self):
        return self.logs

log_stream = LogStream()
logging.basicConfig(stream=log_stream, level=logging.DEBUG)

log = logging.getLogger('test')
log.debug('debugging something')
log.info('informing user')

print(log_stream)

输出：

DEBUG:test:debugging something
INFO:test:informing user

Answer 3

也许这个示例代码就足够了。 通常，您应该发布您的代码，以便我们可以看到正在发生的事情。 在遵循任何给定的教程时，您还应该查看日志记录模块的实际Python文档。 https://docs.python.org/2/library/logging.html

标准Python日志记录模块可以记录到文件。完成日志记录后，可以将该文件的内容打印到shell输出中。

# Do some logging to a file
fname = 'mylog.log'
logging.basicConfig(filename=fname, level=logging.INFO)
logging.info('Started')
logging.info('Finished')

# Print the output
with open(fname, 'r') as f:
    print f.read() # You could also store f.read() to a string