Formatter objects configure the final order, structure, and contents of the log
message. Unlike the base :class:`logging.Handler` class, application code may
instantiate formatter classes, although you could likely subclass the formatter
-if your application needs special behavior. The constructor takes two optional
-arguments: a message format string and a date format string. If there is no
-message format string, the default is to use the raw message. If there is no
-date format string, the default date format is::
+if your application needs special behavior. The constructor takes three
+optional arguments -- a message format string, a date format string and a style
+indicator.
+
+.. method:: logging.Formatter.__init__(fmt=None, datefmt=None, style='%')
+
+If there is no message format string, the default is to use the
+raw message. If there is no date format string, the default date format is::
%Y-%m-%d %H:%M:%S
-with the milliseconds tacked on at the end.
+with the milliseconds tacked on at the end. The ``style`` is one of `%`, '{'
+or '$'. If one of these is not specified, then '%' will be used.
-The message format string uses ``%(<dictionary key>)s`` styled string
-substitution; the possible keys are documented in :ref:`formatter-objects`.
+If the ``style`` is '%', the message format string uses
+``%(<dictionary key>)s`` styled string substitution; the possible keys are
+documented in :ref:`formatter-objects`. If the style is '{', the message format
+string is assumed to be compatible with :meth:`str.format` (using keyword
+arguments), while if the style is '$' then the message format string should
+conform to what is expected by :meth:`string.Template.substitute`.
+
+.. versionchanged:: 3.2
+ Added the ``style`` parameter.
The following message format string will log the time in a human-readable
format, the severity of the message, and the contents of the message, in that
converter = time.localtime
- def __init__(self, fmt=None, datefmt=None):
+ def __init__(self, fmt=None, datefmt=None, style='%'):
"""
Initialize the formatter with specified format strings.
Initialize the formatter either with the specified format string, or a
default as described above. Allow for specialized date formatting with
the optional datefmt argument (if omitted, you get the ISO8601 format).
+
+ Use a style parameter of '%', '{' or '$' to specify that you want to
+ use one of %-formatting, :meth:`str.format` (``{}``) formatting or
+ :class:`string.Template` formatting in your format string.
+
+ .. versionchanged: 3.2
+ Added the ``style`` parameter.
"""
+ if style not in ('%', '$', '{'):
+ style = '%'
+ self._style = style
if fmt:
self._fmt = fmt
else:
- self._fmt = "%(message)s"
+ if style == '%':
+ self._fmt = "%(message)s"
+ elif style == '{':
+ self._fmt = '{message}'
+ else:
+ self._fmt = '${message}'
self.datefmt = datefmt
def formatTime(self, record, datefmt=None):
s = time.strftime(datefmt, ct)
else:
t = time.strftime("%Y-%m-%d %H:%M:%S", ct)
- s = "%s,%03d" % (t, record.msecs)
+ s = "%s,%03d" % (t, record.msecs) # the use of % here is internal
return s
def formatException(self, ei):
"""
Check if the format uses the creation time of the record.
"""
- return self._fmt.find("%(asctime)") >= 0
+ if self._style == '%':
+ result = self._fmt.find("%(asctime)") >= 0
+ elif self._style == '$':
+ result = self._fmt.find("{asctime}") >= 0
+ else:
+ result = self._fmt.find("$asctime") >= 0 or \
+ self._fmt.find("${asctime}") >= 0
+ return result
def format(self, record):
"""
record.message = record.getMessage()
if self.usesTime():
record.asctime = self.formatTime(record, self.datefmt)
- s = self._fmt % record.__dict__
+ style = self._style
+ if style == '%':
+ s = self._fmt % record.__dict__
+ elif style == '{':
+ s = self._fmt.format(**record.__dict__)
+ else:
+ from string import Template
+ s = Template(self._fmt).substitute(**record.__dict__)
if record.exc_info:
# Cache the traceback text to avoid converting it multiple times
# (it's constant anyway)
self.assertEqual(data.name, self.que_logger.name)
self.assertEqual((data.msg, data.args), (msg, None))
+class FormatterTest(unittest.TestCase):
+ def setUp(self):
+ self.common = {
+ 'name': 'formatter.test',
+ 'level': logging.DEBUG,
+ 'pathname': os.path.join('path', 'to', 'dummy.ext'),
+ 'lineno': 42,
+ 'exc_info': None,
+ 'func': None,
+ 'msg': 'Message with %d %s',
+ 'args': (2, 'placeholders'),
+ }
+ self.variants = {
+ }
+
+ def get_record(self, name=None):
+ result = dict(self.common)
+ if name is not None:
+ result.update(self.variants[name])
+ return logging.makeLogRecord(result)
+
+ def test_percent(self):
+ "Test %-formatting"
+ r = self.get_record()
+ f = logging.Formatter('${%(message)s}')
+ self.assertEqual(f.format(r), '${Message with 2 placeholders}')
+ f = logging.Formatter('%(random)s')
+ self.assertRaises(KeyError, f.format, r)
+
+ def test_braces(self):
+ "Test {}-formatting"
+ r = self.get_record()
+ f = logging.Formatter('$%{message}%$', style='{')
+ self.assertEqual(f.format(r), '$%Message with 2 placeholders%$')
+ f = logging.Formatter('{random}', style='{')
+ self.assertRaises(KeyError, f.format, r)
+
+ def test_dollars(self):
+ "Test $-formatting"
+ r = self.get_record()
+ f = logging.Formatter('$message', style='$')
+ self.assertEqual(f.format(r), 'Message with 2 placeholders')
+ f = logging.Formatter('$$%${message}%$$', style='$')
+ self.assertEqual(f.format(r), '$%Message with 2 placeholders%$')
+ f = logging.Formatter('${random}', style='$')
+ self.assertRaises(KeyError, f.format, r)
+
class BaseFileTest(BaseTest):
"Base class for handler tests that write log files"
CustomLevelsAndFiltersTest, MemoryHandlerTest,
ConfigFileTest, SocketHandlerTest, MemoryTest,
EncodingTest, WarningsTest, ConfigDictTest, ManagerTest,
+ FormatterTest,
LogRecordClassTest, ChildLoggerTest, QueueHandlerTest,
RotatingFileHandlerTest,
#TimedRotatingFileHandlerTest
Library
-------
+- logging: Added style option to Formatter to allow %, {} or $-formatting.
+
- Issue #5178: Added tempfile.TemporaryDirectory class that can be used
as a context manager.
projects / thirdparty / Python / cpython.git / commitdiff
