Merge pull request #70 from cgroner/3.2/develop

Document auto update/create columns.

classes/kohana/orm.php

@@ -139,14 +139,17 @@ public static function factory($model, $id = NULL)
 	protected $_table_columns;
 
 	/**
-	 * Auto-update columns for updates
-	 * @var string
+	 * Auto-update column name & format for updates. 
+	 * @see $_created_column
+	 * @var mixed An `array` with 'column' and 'format' keys and values or NULL for no auto update column
 	 */
 	protected $_updated_column = NULL;
 
 	/**
-	 * Auto-update columns for creation
-	 * @var string
+	 * Auto-update column name & format for creation. If 'format' is TRUE, the 
+	 * php 'time()' method will be used, otherwise the 'format' will be passed 
+	 * as the format parameter to the php 'date()' function.
+	 * @var mixed An `array` with 'column' and 'format' keys and values or NULL for no auto update column
 	 */
 	protected $_created_column = NULL;
 

guide/orm/models.md

@@ -26,3 +26,22 @@ ORM assumes each model (and database table) has an `id` column that is indexed a
 For each model, you can define which database configuration ORM will run queries on. If you override the `$_db_group` variable in your model, ORM will connect to that database. Example:
 
 	protected $_db_group = 'alternate';
+
+## Auto-update columns
+
+If you'd like date/time columns automatically updated whenever your model is 
+changed or created you can define the `$_created_column` and/or 
+`$_updated_column` properties in your model. Use an `array` with 'column' 
+and 'format' keys & values, where 'column' is the column name to be updated 
+and 'format' is the date format to use. You can set 'format' to TRUE 
+for a Unix timestamp, or specify a string format like that expected for the 
+php `date()` function.
+
+The following example will automatically update the 'last_changed' column 
+with the current Unix timestamp whenever the model is updated:
+
+	class Model_Member extends ORM
+	{
+		protected $_updated_column = array('column' => 'last_changed',
+		                                   'format' => TRUE);		 
+	}