Merge pull request #2 from fruechel/master

Accept new values from mutate_json_record

Author: marselester

README.rst

@@ -110,7 +110,7 @@ ISO8601 date mutation.
         json_lib = ujson
 
         def mutate_json_record(self, json_record):
-            pass
+            return json_record
 
 Tests
 -----

json_log_formatter/__init__.py

@@ -61,8 +61,13 @@ def format(self, record):
         message = record.getMessage()
         extra = self.extra_from_record(record)
         json_record = self.json_record(message, extra, record)
-        self.mutate_json_record(json_record)
-        return self.json_lib.dumps(json_record)
+        mutated_record = self.mutate_json_record(json_record)
+        # Backwards compatibility: Functions that overwrite this but don't
+        # return a new value will return None because they modified the
+        # argument passed in.
+        if mutated_record is None:
+            mutated_record = json_record
+        return self.json_lib.dumps(mutated_record)
 
     def extra_from_record(self, record):
         """Returns `extra` dict you passed to logger.
@@ -104,3 +109,4 @@ def mutate_json_record(self, json_record):
             attr = json_record[attr_name]
             if isinstance(attr, datetime):
                 json_record[attr_name] = attr.isoformat()
+        return json_record

tests.py

@@ -65,6 +65,27 @@ def test_message_and_time_and_extra_are_in_json_record_when_extra_is_provided(se
         self.assertEqual(set(json_record), expected_fields)
 
 
+class MutatingFormatter(JSONFormatter):
+
+    def mutate_json_record(self, json_record):
+        new_record = {}
+        for k, v in json_record.items():
+            if isinstance(v, datetime):
+                v = v.isoformat()
+            new_record[k] = v
+        return new_record
+
+
+class MutatingFormatterTest(TestCase):
+    def setUp(self):
+        json_handler.setFormatter(MutatingFormatter())
+
+    def test_new_record_accepted(self):
+        logger.info('Sign up', extra={'fizz': DATETIME})
+        json_record = json.loads(log_buffer.getvalue())
+        self.assertEqual(json_record['fizz'], DATETIME_ISO)
+
+
 class JsonLibTest(TestCase):
     def setUp(self):
         json_handler.setFormatter(JSONFormatter())