Adds immutable property fit SluggableBehavior fixes #6430

framework/behaviors/SluggableBehavior.php

@@ -77,6 +77,11 @@ class SluggableBehavior extends AttributeBehavior
      */
     public $value;
     /**
+     * @var boolean whether to generate new slug if it already filled but attribute was changed.
+     * If enabled behavior will not generate new slug after attributes in model was changed.
+     */
+    public $immutable = false;
+    /**
      * @var boolean whether to ensure generated slug value to be unique among owner class records.
      * If enabled behavior will validate slug uniqueness automatically. If validation fails it will attempt
      * generating unique slug value from based one until success.
@@ -133,6 +138,7 @@ class SluggableBehavior extends AttributeBehavior
             $owner = $this->owner;
             if (!$owner->getIsNewRecord() && !empty($owner->{$this->slugAttribute})) {
                 $isNewSlug = false;
+                if(!$this->immutable){
                     foreach ($attributes as $attribute) {
                         if ($owner->isAttributeChanged($attribute)) {
                             $isNewSlug = true;
@@ -140,6 +146,7 @@ class SluggableBehavior extends AttributeBehavior
                         }
                     }
                 }
+            }
 
             if ($isNewSlug) {
                 $slugParts = [];