Python 如何将 log 输入到 Mysql 数据库

logging 模块

logging 将日志打印到文件,需要添加 Handler.那输出至数据库也实现一个 Hanler 不就可以了.

class Handler(Filterer):
    """
    Handler instances dispatch logging events to specific destinations.

    The base handler class. Acts as a placeholder which defines the Handler
    interface. Handlers can optionally use Formatter instances to format
    records as desired. By default, no formatter is specified; in this case,
    the 'raw' message as determined by record.message is logged.
    """
    def __init__(self, level=NOTSET):
        """
        Initializes the instance - basically setting the formatter to None
        and the filter list to empty.
        """
        Filterer.__init__(self)
        self._name = None
        self.level = _checkLevel(level)
        self.formatter = None
        # Add the handler to the global _handlerList (for cleanup on shutdown)
        _addHandlerRef(self)
        self.createLock()

    def get_name(self):
        return self._name

    def set_name(self, name):
        _acquireLock()
        try:
            if self._name in _handlers:
                del _handlers[self._name]
            self._name = name
            if name:
                _handlers[name] = self
        finally:
            _releaseLock()

    name = property(get_name, set_name)

    def createLock(self):
        """
        Acquire a thread lock for serializing access to the underlying I/O.
        """
        self.lock = threading.RLock()
        _register_at_fork_reinit_lock(self)

    def acquire(self):
        """
        Acquire the I/O thread lock.
        """
        if self.lock:
            self.lock.acquire()

    def release(self):
        """
        Release the I/O thread lock.
        """
        if self.lock:
            self.lock.release()

    def setLevel(self, level):
        """
        Set the logging level of this handler.  level must be an int or a str.
        """
        self.level = _checkLevel(level)

    def format(self, record):
        """
        Format the specified record.

        If a formatter is set, use it. Otherwise, use the default formatter
        for the module.
        """
        if self.formatter:
            fmt = self.formatter
        else:
            fmt = _defaultFormatter
        return fmt.format(record)

    def emit(self, record):
        """
        Do whatever it takes to actually log the specified logging record.

        This version is intended to be implemented by subclasses and so
        raises a NotImplementedError.
        """
        raise NotImplementedError('emit must be implemented '
                                  'by Handler subclasses')

    def handle(self, record):
        """
        Conditionally emit the specified logging record.

        Emission depends on filters which may have been added to the handler.
        Wrap the actual emission of the record with acquisition/release of
        the I/O thread lock. Returns whether the filter passed the record for
        emission.
        """
        rv = self.filter(record)
        if rv:
            self.acquire()
            try:
                self.emit(record)
            finally:
                self.release()
        return rv

    def setFormatter(self, fmt):
        """
        Set the formatter for this handler.
        """
        self.formatter = fmt

    def flush(self):
        """
        Ensure all logging output has been flushed.

        This version does nothing and is intended to be implemented by
        subclasses.
        """
        pass

    def close(self):
        """
        Tidy up any resources used by the handler.

        This version removes the handler from an internal map of handlers,
        _handlers, which is used for handler lookup by name. Subclasses
        should ensure that this gets called from overridden close()
        methods.
        """
        #get the module data lock, as we're updating a shared structure.
        _acquireLock()
        try:    #unlikely to raise an exception, but you never know...
            if self._name and self._name in _handlers:
                del _handlers[self._name]
        finally:
            _releaseLock()

    def handleError(self, record):
        """
        Handle errors which occur during an emit() call.

        This method should be called from handlers when an exception is
        encountered during an emit() call. If raiseExceptions is false,
        exceptions get silently ignored. This is what is mostly wanted
        for a logging system - most users will not care about errors in
        the logging system, they are more interested in application errors.
        You could, however, replace this with a custom handler if you wish.
        The record which was being processed is passed in to this method.
        """
        if raiseExceptions and sys.stderr:  # see issue 13807
            t, v, tb = sys.exc_info()
            try:
                sys.stderr.write('--- Logging error ---\n')
                traceback.print_exception(t, v, tb, None, sys.stderr)
                sys.stderr.write('Call stack:\n')
                # Walk the stack frame up until we're out of logging,
                # so as to print the calling context.
                frame = tb.tb_frame
                while (frame and os.path.dirname(frame.f_code.co_filename) ==
                       __path__[0]):
                    frame = frame.f_back
                if frame:
                    traceback.print_stack(frame, file=sys.stderr)
                else:
                    # couldn't find the right stack frame, for some reason
                    sys.stderr.write('Logged from file %s, line %s\n' % (
                                     record.filename, record.lineno))
                # Issue 18671: output logging message and arguments
                try:
                    sys.stderr.write('Message: %r\n'
                                     'Arguments: %s\n' % (record.msg,
                                                          record.args))
                except RecursionError:  # See issue 36272
                    raise
                except Exception:
                    sys.stderr.write('Unable to print the message and arguments'
                                     ' - possible formatting error.\nUse the'
                                     ' traceback above to help find the error.\n'
                                    )
            except OSError: #pragma: no cover
                pass    # see issue 5971
            finally:
                del t, v, tb

    def __repr__(self):
        level = getLevelName(self.level)
        return '<%s (%s)>' % (self.__class__.__name__, level)
​

需要重写的方法

    def emit(self, record):
        """
        Do whatever it takes to actually log the specified logging record.

        This version is intended to be implemented by subclasses and so
        raises a NotImplementedError.
        """
        raise NotImplementedError('emit must be implemented '
                                  'by Handler subclasses')
​

其中 record 对象是 LogRecord 对象.

class LogRecord(object):
    """
    A LogRecord instance represents an event being logged.

    LogRecord instances are created every time something is logged. They
    contain all the information pertinent to the event being logged. The
    main information passed in is in msg and args, which are combined
    using str(msg) % args to create the message field of the record. The
    record also includes information such as when the record was created,
    the source line where the logging call was made, and any exception
    information to be logged.
    """
    def __init__(self, name, level, pathname, lineno,
                 msg, args, exc_info, func=None, sinfo=None, **kwargs):
        """
        Initialize a logging record with interesting information.
        """
        ct = time.time()
        self.name = name
        self.msg = msg
        #
        # The following statement allows passing of a dictionary as a sole
        # argument, so that you can do something like
        #  logging.debug("a %(a)d b %(b)s", {'a':1, 'b':2})
        # Suggested by Stefan Behnel.
        # Note that without the test for args[0], we get a problem because
        # during formatting, we test to see if the arg is present using
        # 'if self.args:'. If the event being logged is e.g. 'Value is %d'
        # and if the passed arg fails 'if self.args:' then no formatting
        # is done. For example, logger.warning('Value is %d', 0) would log
        # 'Value is %d' instead of 'Value is 0'.
        # For the use case of passing a dictionary, this should not be a
        # problem.
        # Issue #21172: a request was made to relax the isinstance check
        # to hasattr(args[0], '__getitem__'). However, the docs on string
        # formatting still seem to suggest a mapping object is required.
        # Thus, while not removing the isinstance check, it does now look
        # for collections.abc.Mapping rather than, as before, dict.
        if (args and len(args) == 1 and isinstance(args[0], collections.abc.Mapping)
            and args[0]):
            args = args[0]
        self.args = args
        self.levelname = getLevelName(level)
        self.levelno = level
        self.pathname = pathname
        try:
            self.filename = os.path.basename(pathname)
            self.module = os.path.splitext(self.filename)[0]
        except (TypeError, ValueError, AttributeError):
            self.filename = pathname
            self.module = "Unknown module"
        self.exc_info = exc_info
        self.exc_text = None      # used to cache the traceback text
        self.stack_info = sinfo
        self.lineno = lineno
        self.funcName = func
        self.created = ct
        self.msecs = (ct - int(ct)) * 1000
        self.relativeCreated = (self.created - _startTime) * 1000
        if logThreads:
            self.thread = threading.get_ident()
            self.threadName = threading.current_thread().name
        else: # pragma: no cover
            self.thread = None
            self.threadName = None
        if not logMultiprocessing: # pragma: no cover
            self.processName = None
        else:
            self.processName = 'MainProcess'
            mp = sys.modules.get('multiprocessing')
            if mp is not None:
                # Errors may occur if multiprocessing has not finished loading
                # yet - e.g. if a custom import hook causes third-party code
                # to run when multiprocessing calls import. See issue 8200
                # for an example
                try:
                    self.processName = mp.current_process().name
                except Exception: #pragma: no cover
                    pass
        if logProcesses and hasattr(os, 'getpid'):
            self.process = os.getpid()
        else:
            self.process = None

    def __str__(self):
        return '<LogRecord: %s, %s, %s, %s, "%s">'%(self.name, self.levelno,
            self.pathname, self.lineno, self.msg)

    __repr__ = __str__

    def getMessage(self):
        """
        Return the message for this LogRecord.

        Return the message for this LogRecord after merging any user-supplied
        arguments with the message.
        """
        msg = str(self.msg)
        if self.args:
            msg = msg % self.args
        return msg
​

其中有很多需要用到的属性.
下面贴上 Handler 实现

from logging import Handler, LogRecord, NOTSET, _checkLevel, _addHandlerRef, Filterer

from sqlalchemy.engine import create_engine

from sqlalchemy import Column, String, Integer, DateTime

from sqlalchemy.orm import sessionmaker

from sqlalchemy.ext.declarative import declarative_base



Base = declarative_base()





class LogTable(Base):

    __tablename__ = 'log'

    id = Column(Integer, primary_key=True, autoincrement=True)

    logger_name = Column(String(16))

    msg = Column(String(64))

    levelname = Column(String(8))

    timestamp = Column(DateTime)

    lineno = Column(Integer)





class MySQLHandler(Handler):

    def __init__(self, level=NOTSET, host='localhost', port=3306, user='root', password='', engine='pymysql',

                 database='log', *args,

                 **kwargs):

        """



        :param host: Host of server

        :param port: Port of server

        :param user: MySQL user

        :param password:

        :param engine: Default engine is pymysql.

        :param database: Default value is log.

        :param args:

        :param kwargs: use when create engine.

        """

        Filterer.__init__(self)

        self._name = None

        self.level = _checkLevel(level)

        self.formatter = None

        # Add the handler to the global _handlerList (for cleanup on shutdown)

        _addHandlerRef(self)

        self.createLock()

        self.engine = create_engine('mysql+{engine}://{user}:{psw}@{host}:{port}/{db}'.format(engine=engine,

                                                                                              user=user,

                                                                                              psw=password,

                                                                                              host=host,

                                                                                              port=port,

                                                                                              db=database))

        self.Session = sessionmaker(bind=engine)



    def emit(self, record: LogRecord):

        log = LogTable(

            msg=record.msg,

            logger_name=record.name,

            levelname=record.levelname,

            timestamp=record.created,

            lineno=record.lineno

        )

        session = self.Session()

        session.add(log)

        session.commit()
​