use an AfterSaveEvent class to be consistent

framework/base/ModelEvent.php

@@ -8,9 +8,7 @@
 namespace yii\base;
 
 /**
- * ModelEvent class.
- *
- * ModelEvent represents the parameter needed by model events.
+ * ModelEvent represents the parameter needed by [[Model]] events.
  *
  * @author Qiang Xue <qiang.xue@gmail.com>
  * @since 2.0

framework/classes.php

@@ -88,6 +88,7 @@ return [
   'yii\db\ActiveRecord' => YII_PATH . '/db/ActiveRecord.php',
   'yii\db\ActiveRecordInterface' => YII_PATH . '/db/ActiveRecordInterface.php',
   'yii\db\ActiveRelationTrait' => YII_PATH . '/db/ActiveRelationTrait.php',
+  'yii\db\AfterSaveEvent' => YII_PATH . '/db/AfterSaveEvent.php',
   'yii\db\BaseActiveRecord' => YII_PATH . '/db/BaseActiveRecord.php',
   'yii\db\BatchQueryResult' => YII_PATH . '/db/BatchQueryResult.php',
   'yii\db\ColumnSchema' => YII_PATH . '/db/ColumnSchema.php',

framework/db/AfterSaveEvent.php

+<?php
+/**
+ * @link http://www.yiiframework.com/
+ * @copyright Copyright (c) 2008 Yii Software LLC
+ * @license http://www.yiiframework.com/license/
+ */
+
+namespace yii\db;
+
+use yii\base\Event;
+
+/**
+ * AfterSaveEvent represents the information available in [[ActiveRecord::EVENT_AFTER_INSERT]] and [[ActiveRecord::EVENT_AFTER_UPDATE]].
+ *
+ * @author Carsten Brandt <mail@cebe.cc>
+ * @since 2.0
+ */
+class AfterSaveEvent extends Event
+{
+    /**
+     * @var array The attribute values that had changed and were saved.
+     */
+    public $changedAttributes;
+}

framework/db/BaseActiveRecord.php

@@ -867,17 +867,17 @@ abstract class BaseActiveRecord extends Model implements ActiveRecordInterface
     /**
      * This method is called at the end of inserting or updating a record.
      * The default implementation will trigger an [[EVENT_AFTER_INSERT]] event when `$insert` is true,
-     * or an [[EVENT_AFTER_UPDATE]] event if `$insert` is false.
+     * or an [[EVENT_AFTER_UPDATE]] event if `$insert` is false. The event class used is [[AfterSaveEvent]].
      * When overriding this method, make sure you call the parent implementation so that
      * the event is triggered.
      * @param boolean $insert whether this method called while inserting a record.
-     * @param array $changedAttributes the attribute values that have changed during save.
      * If false, it means the method is called while updating a record.
+     * @param array $changedAttributes The attribute values that had changed and were saved.
      */
     public function afterSave($insert, $changedAttributes)
     {
-        $this->trigger($insert ? self::EVENT_AFTER_INSERT : self::EVENT_AFTER_UPDATE, new ModelEvent([
-            'data' => ['changedAttributes' => $changedAttributes]
+        $this->trigger($insert ? self::EVENT_AFTER_INSERT : self::EVENT_AFTER_UPDATE, new AfterSaveEvent([
+            'changedAttributes' => $changedAttributes
         ]));
     }