docs for scrapy.logformatter

docs/topics/logging.rst

@@ -193,6 +193,45 @@ to override some of the Scrapy settings regarding logging.
     Module `logging.handlers <https://docs.python.org/2/library/logging.handlers.html>`_
         Further documentation on available handlers
 
+Custom Log Formats
+-------------------
+
+Custom log format can be set for different actions by extending ``scrapy.logformatter.LogFormatter`` class.
+
+Each method of ``scrapy.logformatter.LogFormatter`` represents an action. All methods inherited from 
+``scrapy.logformatter.LogFormatter`` in your custom log formatting class must return a dictionary listing
+the parameters ``level``, ``msg`` and ``args`` which are going to be used for constructing the log message.
+Listed below is details of what each key represents :
+
+*   ``level`` is the log level for that action, you can use those from the python logging library:
+    :setting:`logging.DEBUG`, :setting:`logging.INFO`, :setting:`logging.WARNING`, :setting:`logging.ERROR`
+    and :setting:`logging.CRITICAL`.
+
+*   ``msg`` should be a string that can contain different formatting placeholders. This string, formatted
+    with the provided ``args``, is going to be the long message for that action.
+
+*   ``args`` should be a tuple or dict with the formatting placeholders for `msg`. The final log message is
+    computed as ``msg % args``.
+
+.. note:: To use custom log formatting class, you must mention it in ``settings.py``, by adding a line 
+   ``LOG_FORMATTER = '<path_to_your_class>’``
+ 
+.. class:: scrapy.logformatter.LogFormatter
+
+   The default log formatting class in Scrapy.
+
+   .. method:: crawled (request, response, spider)
+
+      ``crawled`` is called to log message when the crawler finds a webpage.
+
+   .. method:: scraped(item, response, spider)
+
+      ``scraped`` is called to log message when an item scraped by a spider.
+
+   .. method::  dropped(item, exception, response, spider)  
+
+      ``dropped`` is called to log message when an item is dropped while it is passing through the item pipeline. 
+
 Advanced customization
 ----------------------