[Python-checkins] bpo-40884: Added defaults parameter for logging.Formatter (GH-20668)
Bar Harel
webhook-mailer at python.org
Thu Jun 18 10:19:03 EDT 2020
https://github.com/python/cpython/commit/8f192d12af82c4dc40730bf59814f6a68f68f950
commit: 8f192d12af82c4dc40730bf59814f6a68f68f950
branch: master
author: Bar Harel <bzvi7919 at gmail.com>
committer: GitHub <noreply at github.com>
date: 2020-06-18T07:18:58-07:00
summary:
bpo-40884: Added defaults parameter for logging.Formatter (GH-20668)
Docs and tests are underway.
Automerge-Triggered-By: @vsajip
files:
A Misc/NEWS.d/next/Library/2020-06-06-02-42-26.bpo-40884.n7fOwS.rst
M Doc/library/logging.rst
M Lib/logging/__init__.py
M Lib/test/test_logging.py
diff --git a/Doc/library/logging.rst b/Doc/library/logging.rst
index 7267f812cc192..3ff67f76cc3c5 100644
--- a/Doc/library/logging.rst
+++ b/Doc/library/logging.rst
@@ -529,7 +529,8 @@ The useful mapping keys in a :class:`LogRecord` are given in the section on
:ref:`logrecord-attributes`.
-.. class:: Formatter(fmt=None, datefmt=None, style='%', validate=True)
+.. class:: Formatter(fmt=None, datefmt=None, style='%', validate=True, *,
+ defaults=None)
Returns a new instance of the :class:`Formatter` class. The instance is
initialized with a format string for the message as a whole, as well as a
@@ -545,6 +546,10 @@ The useful mapping keys in a :class:`LogRecord` are given in the section on
:ref:`formatting-styles` for more information on using {- and $-formatting
for log messages.
+ The *defaults* parameter can be a dictionary with default values to use in
+ custom fields. For example:
+ ``logging.Formatter('%(ip)s %(message)s', defaults={"ip": None})``
+
.. versionchanged:: 3.2
The *style* parameter was added.
@@ -553,6 +558,9 @@ The useful mapping keys in a :class:`LogRecord` are given in the section on
will raise a ``ValueError``.
For example: ``logging.Formatter('%(asctime)s - %(message)s', style='{')``.
+ .. versionchanged:: 3.10
+ The *defaults* parameter was added.
+
.. method:: format(record)
The record's attribute dictionary is used as the operand to a string
diff --git a/Lib/logging/__init__.py b/Lib/logging/__init__.py
index 1c446fd421650..94361ca75f4f3 100644
--- a/Lib/logging/__init__.py
+++ b/Lib/logging/__init__.py
@@ -411,8 +411,9 @@ class PercentStyle(object):
asctime_search = '%(asctime)'
validation_pattern = re.compile(r'%\(\w+\)[#0+ -]*(\*|\d+)?(\.(\*|\d+))?[diouxefgcrsa%]', re.I)
- def __init__(self, fmt):
+ def __init__(self, fmt, *, defaults=None):
self._fmt = fmt or self.default_format
+ self._defaults = defaults
def usesTime(self):
return self._fmt.find(self.asctime_search) >= 0
@@ -423,7 +424,11 @@ def validate(self):
raise ValueError("Invalid format '%s' for '%s' style" % (self._fmt, self.default_format[0]))
def _format(self, record):
- return self._fmt % record.__dict__
+ if defaults := self._defaults:
+ values = defaults | record.__dict__
+ else:
+ values = record.__dict__
+ return self._fmt % values
def format(self, record):
try:
@@ -441,7 +446,11 @@ class StrFormatStyle(PercentStyle):
field_spec = re.compile(r'^(\d+|\w+)(\.\w+|\[[^]]+\])*$')
def _format(self, record):
- return self._fmt.format(**record.__dict__)
+ if defaults := self._defaults:
+ values = defaults | record.__dict__
+ else:
+ values = record.__dict__
+ return self._fmt.format(**values)
def validate(self):
"""Validate the input format, ensure it is the correct string formatting style"""
@@ -467,8 +476,8 @@ class StringTemplateStyle(PercentStyle):
asctime_format = '${asctime}'
asctime_search = '${asctime}'
- def __init__(self, fmt):
- self._fmt = fmt or self.default_format
+ def __init__(self, *args, **kwargs):
+ super().__init__(*args, **kwargs)
self._tpl = Template(self._fmt)
def usesTime(self):
@@ -490,7 +499,11 @@ def validate(self):
raise ValueError('invalid format: no fields')
def _format(self, record):
- return self._tpl.substitute(**record.__dict__)
+ if defaults := self._defaults:
+ values = defaults | record.__dict__
+ else:
+ values = record.__dict__
+ return self._tpl.substitute(**values)
BASIC_FORMAT = "%(levelname)s:%(name)s:%(message)s"
@@ -546,7 +559,8 @@ class Formatter(object):
converter = time.localtime
- def __init__(self, fmt=None, datefmt=None, style='%', validate=True):
+ def __init__(self, fmt=None, datefmt=None, style='%', validate=True, *,
+ defaults=None):
"""
Initialize the formatter with specified format strings.
@@ -565,7 +579,7 @@ def __init__(self, fmt=None, datefmt=None, style='%', validate=True):
if style not in _STYLES:
raise ValueError('Style must be one of: %s' % ','.join(
_STYLES.keys()))
- self._style = _STYLES[style][0](fmt)
+ self._style = _STYLES[style][0](fmt, defaults=defaults)
if validate:
self._style.validate()
diff --git a/Lib/test/test_logging.py b/Lib/test/test_logging.py
index e719d264a9191..2ae00b6e3b4e9 100644
--- a/Lib/test/test_logging.py
+++ b/Lib/test/test_logging.py
@@ -3710,6 +3710,9 @@ def setUp(self):
'args': (2, 'placeholders'),
}
self.variants = {
+ 'custom': {
+ 'custom': 1234
+ }
}
def get_record(self, name=None):
@@ -3926,6 +3929,26 @@ def test_format_validate(self):
)
self.assertRaises(ValueError, logging.Formatter, '${asctime', style='$')
+ def test_defaults_parameter(self):
+ fmts = ['%(custom)s %(message)s', '{custom} {message}', '$custom $message']
+ styles = ['%', '{', '$']
+ for fmt, style in zip(fmts, styles):
+ f = logging.Formatter(fmt, style=style, defaults={'custom': 'Default'})
+ r = self.get_record()
+ self.assertEqual(f.format(r), 'Default Message with 2 placeholders')
+ r = self.get_record("custom")
+ self.assertEqual(f.format(r), '1234 Message with 2 placeholders')
+
+ # Without default
+ f = logging.Formatter(fmt, style=style)
+ r = self.get_record()
+ self.assertRaises(ValueError, f.format, r)
+
+ # Non-existing default is ignored
+ f = logging.Formatter(fmt, style=style, defaults={'Non-existing': 'Default'})
+ r = self.get_record("custom")
+ self.assertEqual(f.format(r), '1234 Message with 2 placeholders')
+
def test_invalid_style(self):
self.assertRaises(ValueError, logging.Formatter, None, None, 'x')
diff --git a/Misc/NEWS.d/next/Library/2020-06-06-02-42-26.bpo-40884.n7fOwS.rst b/Misc/NEWS.d/next/Library/2020-06-06-02-42-26.bpo-40884.n7fOwS.rst
new file mode 100644
index 0000000000000..64990e8023fba
--- /dev/null
+++ b/Misc/NEWS.d/next/Library/2020-06-06-02-42-26.bpo-40884.n7fOwS.rst
@@ -0,0 +1,3 @@
+Added a `defaults` parameter to :class:`logging.Formatter`, to allow
+specifying default values for custom fields. Patch by Asaf Alon and Bar
+Harel.
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