LeMeteore · December 23, 2016 10:44 · Dec 21, 2016 · Dec 21, 2016
diff --git a/chromelogger.py b/chromelogger.py
@@ -1,4 +1,6 @@
 """
+License: MIT - https://opensource.org/licenses/MIT
+
 ChromeLogger is a protocol which allows sending logging messages to the Browser.
 
 This module implements simple support for Django. It consists of two components:

diff --git a/chromelogger.py b/chromelogger.py
@@ -0,0 +1,99 @@
+"""
+ChromeLogger is a protocol which allows sending logging messages to the Browser.
+
+This module implements simple support for Django. It consists of two components:
+
+    * `LoggingMiddleware` which is responsible for sending all log messages
+      associated with the request to the browser.
+    * `ChromeLoggerHandler` a python logging handler which collects all messages.
+
+Configuration in settings.py is as follows::
+
+    MIDDLEWARE = [
+        'chromelogger.LoggingMiddleware',
+        ... # other middlewares
+    ]
+
+    LOGGING = {
+        ...
+        'handlers': {
+            'browser': {
+                'class': 'chromelogger.ChromeLoggerHandler',
+            },
+            ...
+        },
+        'loggers': {
+            'django': {
+                'handlers': ['console', 'browser'],
+                'level': 'DEBUG',
+            },
+            ...
+        }
+    }
+
+"""
+import json
+import logging
+import threading
+
+HEADER_DATA = {
+    'version': 1,
+    'columns': ['log', 'backtrace', 'type'],
+}
+
+STORAGE = threading.local()
+
+
+def map_level(level):
+    """Maps a logging level to a string understood by browser devtools."""
+    if level >= logging.ERROR:
+        return 'error'
+    elif level >= logging.WARNING:
+        return 'warn'
+    elif level >= logging.INFO:
+        return 'info'
+    return ''
+
+
+def encode_data(data):
+    """Return a base64 encoded json dump."""
+    bytes = json.dumps(data).encode('utf-8').encode('base64').replace('\n', '')
+    assert len(bytes) < 250 * 1024
+    return bytes
+
+
+class ChromeLoggerHandler(logging.Handler):
+    def emit(self, record):
+        try:
+            STORAGE.records.append(record)
+        except AttributeError:
+            pass
+
+
+def LoggingMiddleware(get_respone):
+    def middleware(request):
+        STORAGE.records = log_records = []
+
+        try:
+            response = get_respone(request)
+
+            logging_data = HEADER_DATA.copy()
+            rows = [
+                [['{}:'.format(record.name), record.getMessage().strip()],
+                '{} : {}'.format(record.pathname, record.lineno),
+                map_level(record.levelno)]
+                for record in log_records
+            ]
+            rows.insert(0, [
+                ['{} request to {}'.format(request.method, request.get_full_path())],
+                '', 'group'
+            ])
+            rows.append([[], '', 'groupEnd'])
+            logging_data['rows'] = rows
+            response['X-ChromeLogger-Data'] = encode_data(logging_data)
+            return response
+
+        finally:
+            del STORAGE.records
+
+    return middleware