ISO format all date/time objects by default

* the `datefmt` parameter is intended to be used
  by logging.Formatter.formatTime and not for the serialization
* seconds are lost in the serialization of time and datetimes instances

Author: Romain Dartigues

src/pythonjsonlogger/jsonlogger.py

@@ -67,15 +67,8 @@ def __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.datetime):
-                    if obj.year < 1900:
-                        # strftime do not work with date < 1900
-                        return obj.isoformat()
-                    return obj.strftime(self.datefmt or '%Y-%m-%dT%H:%M')
-                elif isinstance(obj, datetime.date):
+                if isinstance(obj, (datetime.date, datetime.time)):
                     return obj.isoformat()
-                elif isinstance(obj, datetime.time):
-                    return obj.strftime('%H:%M')
                 elif istraceback(obj):
                     tb = ''.join(traceback.format_tb(obj))
                     return tb.strip()

tests/tests.py

@@ -123,11 +123,11 @@ def testJsonDefaultEncoder(self):
                "otherdatetimeagain": datetime.datetime(1900, 1, 1)}
         self.logger.info(msg)
         logJson = json.loads(self.buffer.getvalue())
-        self.assertEqual(logJson.get("adate"), "1999-12-31T23:59")
+	self.assertEqual(logJson.get("adate"), "1999-12-31T23:59:00")
         self.assertEqual(logJson.get("otherdate"), "1789-07-14")
         self.assertEqual(logJson.get("otherdatetime"), "1789-07-14T23:59:00")
         self.assertEqual(logJson.get("otherdatetimeagain"),
-                         "1900-01-01T00:00")
+                         "1900-01-01T00:00:00")
 
     def testJsonCustomDefault(self):
         def custom(o):