support formatter styles '{' and '$' with Python 3.2 or above

fluent/handler.py

@@ -24,19 +24,36 @@ class FluentRecordFormatter(logging.Formatter, object):
 
     :param fmt: a dict with format string as values to map to provided keys.
     :param datefmt: strftime()-compatible date/time format string.
-    :param style: (NOT USED)
+    :param style: '%', '{' or '$' (used only with Python 3.2 or above)
     :param fill_missing_fmt_key: if True, do not raise a KeyError if the format
         key is not found. Put None if not found.s
     """
     def __init__(self, fmt=None, datefmt=None, style='%', fill_missing_fmt_key=False):
         super(FluentRecordFormatter, self).__init__(None, datefmt)
 
-        if not fmt:
-            self._fmt_dict = {
+        if sys.version_info[0:2] >= (3, 2) and style != '%':
+            self.__style, basic_fmt_dict = {
+                '{': (logging.StrFormatStyle, {
+                    'sys_host': '{hostname}',
+                    'sys_name': '{name}',
+                    'sys_module': '{module}',
+                }),
+                '$': (logging.StringTemplateStyle, {
+                    'sys_host': '${hostname}',
+                    'sys_name': '${name}',
+                    'sys_module': '${module}',
+                }),
+            }[style]
+        else:
+            self.__style = None
+            basic_fmt_dict = {
                 'sys_host': '%(hostname)s',
                 'sys_name': '%(name)s',
                 'sys_module': '%(module)s',
             }
+
+        if not fmt:
+            self._fmt_dict = basic_fmt_dict
         else:
             self._fmt_dict = fmt
 
@@ -58,7 +75,10 @@ def format(self, record):
         data = {}
         for key, value in self._fmt_dict.items():
             try:
-                value = value % record.__dict__
+                if self.__style:
+                    value = self.__style(value).format(record)
+                else:
+                    value = value % record.__dict__
             except KeyError as exc:
                 value = None
                 if not self.fill_missing_fmt_key:

tests/test_handler.py

@@ -1,6 +1,7 @@
 # -*- coding: utf-8 -*-
 
 import logging
+import sys
 import unittest
 
 import fluent.handler
@@ -62,6 +63,52 @@ def test_custom_fmt(self):
         self.assertTrue('lineno' in data[0][2])
         self.assertTrue('emitted_at' in data[0][2])
 
+    @unittest.skipUnless(sys.version_info[0:2] >= (3, 2), 'supported with Python 3.2 or above')
+    def test_custom_fmt_with_format_style(self):
+        handler = fluent.handler.FluentHandler('app.follow', port=self._port)
+
+        logging.basicConfig(level=logging.INFO)
+        log = logging.getLogger('fluent.test')
+        handler.setFormatter(
+            fluent.handler.FluentRecordFormatter(fmt={
+                'name': '{name}',
+                'lineno': '{lineno}',
+                'emitted_at': '{asctime}',
+            }, style='{')
+        )
+        log.addHandler(handler)
+        log.info({'sample': 'value'})
+        handler.close()
+
+        data = self.get_data()
+        self.assertTrue('name' in data[0][2])
+        self.assertEqual('fluent.test', data[0][2]['name'])
+        self.assertTrue('lineno' in data[0][2])
+        self.assertTrue('emitted_at' in data[0][2])
+
+    @unittest.skipUnless(sys.version_info[0:2] >= (3, 2), 'supported with Python 3.2 or above')
+    def test_custom_fmt_with_template_style(self):
+        handler = fluent.handler.FluentHandler('app.follow', port=self._port)
+
+        logging.basicConfig(level=logging.INFO)
+        log = logging.getLogger('fluent.test')
+        handler.setFormatter(
+            fluent.handler.FluentRecordFormatter(fmt={
+                'name': '${name}',
+                'lineno': '${lineno}',
+                'emitted_at': '${asctime}',
+            }, style='$')
+        )
+        log.addHandler(handler)
+        log.info({'sample': 'value'})
+        handler.close()
+
+        data = self.get_data()
+        self.assertTrue('name' in data[0][2])
+        self.assertEqual('fluent.test', data[0][2]['name'])
+        self.assertTrue('lineno' in data[0][2])
+        self.assertTrue('emitted_at' in data[0][2])
+
     def test_custom_field_raise_exception(self):
         handler = fluent.handler.FluentHandler('app.follow', port=self._port)