Merge pull request #60 from UseAlloy/extend-extensibility

Extend extensibility

Author: madzak

setup.py

@@ -32,6 +32,8 @@
         'Programming Language :: Python :: 3.2',
         'Programming Language :: Python :: 3.3',
         'Programming Language :: Python :: 3.4',
+        'Programming Language :: Python :: 3.5',
+        'Programming Language :: Python :: 3.6',
         'Topic :: System :: Logging',
     ]
 )

src/pythonjsonlogger/jsonlogger.py

@@ -5,7 +5,7 @@
 import logging
 import json
 import re
-import datetime
+from datetime import date, datetime, time
 import traceback
 
 from inspect import istraceback
@@ -24,10 +24,8 @@
     'msecs', 'message', 'msg', 'name', 'pathname', 'process',
     'processName', 'relativeCreated', 'stack_info', 'thread', 'threadName')
 
-RESERVED_ATTR_HASH = dict(zip(RESERVED_ATTRS, RESERVED_ATTRS))
 
-
-def merge_record_extra(record, target, reserved=RESERVED_ATTR_HASH):
+def merge_record_extra(record, target, reserved):
     """
     Merges extra attributes from LogRecord object into target dictionary
 
@@ -44,6 +42,36 @@ def merge_record_extra(record, target, reserved=RESERVED_ATTR_HASH):
     return target
 
 
+class JsonEncoder(json.JSONEncoder):
+    """
+    A custom encoder extending the default JSONEncoder
+    """
+    def default(self, obj):
+        if isinstance(obj, (date, datetime, time)):
+            return self.format_datetime_obj(obj)
+
+        elif istraceback(obj):
+            return ''.join(traceback.format_tb(obj)).strip()
+
+        elif type(obj) == Exception \
+                or isinstance(obj, Exception) \
+                or type(obj) == type:
+            return str(obj)
+
+        try:
+            return super(JsonEncoder, self).default(obj)
+
+        except TypeError:
+            try:
+                return str(obj)
+
+            except Exception:
+                return None
+
+    def format_datetime_obj(self, obj):
+        return obj.isoformat()
+
+
 class JsonFormatter(logging.Formatter):
     """
     A custom formatter to format logging records as json strings.
@@ -58,32 +86,36 @@ def __init__(self, *args, **kwargs):
         :param json_encoder: optional custom encoder
         :param json_serializer: a :meth:`json.dumps`-compatible callable
             that will be used to serialize the log record.
+        :param json_indent: an optional :meth:`json.dumps`-compatible numeric value
+            that will be used to customize the indent of the output json.
         :param prefix: an optional string prefix added at the beginning of
             the formatted string
+        :param reserved_attrs: an optional list of fields that will be skipped when
+            outputting json log record. Defaults to all log record attributes:
+            http://docs.python.org/library/logging.html#logrecord-attributes
+        :param timestamp: an optional string/boolean field to add a timestamp when
+            outputting the json log record. If string is passed, timestamp will be added
+            to log record using string as key. If True boolean is passed, timestamp key
+            will be "timestamp". Defaults to False/off.
         """
         self.json_default = kwargs.pop("json_default", None)
         self.json_encoder = kwargs.pop("json_encoder", None)
         self.json_serializer = kwargs.pop("json_serializer", json.dumps)
         self.json_indent = kwargs.pop("json_indent", None)
         self.prefix = kwargs.pop("prefix", "")
+        reserved_attrs = kwargs.pop("reserved_attrs", RESERVED_ATTRS)
+        self.reserved_attrs = dict(zip(reserved_attrs, reserved_attrs))
+        self.timestamp = kwargs.pop("timestamp", False)
+
         #super(JsonFormatter, self).__init__(*args, **kwargs)
         logging.Formatter.__init__(self, *args, **kwargs)
         if not self.json_encoder and not self.json_default:
-            def _default_json_handler(obj):
-                '''Prints dates in ISO format'''
-                if isinstance(obj, (datetime.date, datetime.time)):
-                    return obj.isoformat()
-                elif istraceback(obj):
-                    tb = ''.join(traceback.format_tb(obj))
-                    return tb.strip()
-                elif isinstance(obj, Exception):
-                    return "Exception: %s" % str(obj)
-                return str(obj)
-            self.json_default = _default_json_handler
+            self.json_encoder = JsonEncoder
+
         self._required_fields = self.parse()
         self._skip_fields = dict(zip(self._required_fields,
                                      self._required_fields))
-        self._skip_fields.update(RESERVED_ATTR_HASH)
+        self._skip_fields.update(self.reserved_attrs)
 
     def parse(self):
         """
@@ -104,6 +136,10 @@ def add_fields(self, log_record, record, message_dict):
         log_record.update(message_dict)
         merge_record_extra(record, log_record, reserved=self._skip_fields)
 
+        if self.timestamp:
+            key = self.timestamp if type(self.timestamp) == str else 'timestamp'
+            log_record[key] = datetime.utcnow()
+
     def process_log_record(self, log_record):
         """
         Override this method to implement custom logic