diff --git a/behaviors/CommentBehavior.php b/behaviors/CommentBehavior.php
new file mode 100644
index 0000000..66641fd
--- /dev/null
+++ b/behaviors/CommentBehavior.php
@@ -0,0 +1,207 @@
+<?php
+    
+    namespace artweb\artbox\comment\behaviors;
+    
+    use artweb\artbox\comment\models\CommentModel;
+    use artweb\artbox\comment\models\interfaces\RatingCacheInterface;
+    use yii\base\Behavior;
+    use yii\base\InvalidConfigException;
+    use yii\db\ActiveQuery;
+    use yii\db\ActiveRecord;
+    
+    /**
+     * Class CommentBehavior
+     *
+     * @property ActiveQuery    $averageRating
+     * @property CommentModel[] $comments
+     * @package artweb\artbox\comment\behaviors
+     */
+    class CommentBehavior extends Behavior
+    {
+        
+        /**
+         * Fully-classified name of class to hold rating cache
+         *
+         * @var string
+         */
+        private $cacheModelName = '';
+        
+        /**
+         * Class to hold rating cache
+         *
+         * @var RatingCacheInterface
+         */
+        private $cacheModel = null;
+        
+        /**
+         * Whether to cache rating or not
+         *
+         * @var bool
+         */
+        private $cacheRating = false;
+        
+        /**
+         * @inheritdoc
+         */
+        public function attach($owner)
+        {
+            if ($this->cacheRating) {
+                if (empty( $this->cacheModelName ) || !is_string($this->cacheModelName)) {
+                    throw new InvalidConfigException(
+                        'To use rating cache you must set $cacheModelName where to store it'
+                    );
+                }
+                $this->setCacheModel(
+                    \Yii::createObject(
+                        [
+                            'class' => $this->cacheModelName,
+                        ]
+                    )
+                );
+            }
+            parent::attach($owner);
+        }
+        
+        /**
+         * Get fully-classified name of class to hold rating cache
+         *
+         * @return string
+         */
+        public function getCacheModelName():string
+        {
+            return $this->cacheModelName;
+        }
+        
+        /**
+         * Set fully-classified name of class to hold rating cache
+         *
+         * @param string $value
+         */
+        public function setCacheModelName(string $value)
+        {
+            $this->cacheModelName = $value;
+        }
+        
+        /**
+         * Get model to hold rating cache
+         *
+         * @return \artweb\artbox\comment\models\interfaces\RatingCacheInterface
+         */
+        public function getCacheModel():RatingCacheInterface
+        {
+            return $this->cacheModel;
+        }
+        
+        /**
+         * Set model to hold cache
+         *
+         * @param \artweb\artbox\comment\models\interfaces\RatingCacheInterface|null $value
+         */
+        private function setCacheModel(RatingCacheInterface $value = null)
+        {
+            $this->cacheModel = $value;
+        }
+        
+        /**
+         * Whether cache rating or not
+         *
+         * @return bool
+         */
+        public function getCacheRating(): bool
+        {
+            return $this->cacheRating;
+        }
+        
+        /**
+         * Set whether to cache rating or not
+         *
+         * @param bool $value
+         */
+        public function setCacheRating(bool $value)
+        {
+            $this->cacheRating = $value;
+        }
+        
+        /**
+         * Get query to get all comments for current $owner model
+         *
+         * @return \yii\db\ActiveQuery
+         */
+        public function getComments(): ActiveQuery
+        {
+            /**
+             * @var ActiveRecord $owner
+             */
+            $owner = $this->owner;
+            $pk = $owner->primaryKey()[ 0 ];
+            $query = $owner->hasMany(CommentModel::className(), [ 'entity_id' => $pk ])
+                           ->where(
+                               [
+                                   'artbox_comment.entity'             => $owner::className(),
+                                   'artbox_comment.status'             => CommentModel::STATUS_ACTIVE,
+                                   'artbox_comment.artbox_comment_pid' => null,
+                               ]
+                           );
+            return $query;
+        }
+        
+        /**
+         * Get query to get average rating for current $owner model if it cached
+         *
+         * @return \yii\db\ActiveQuery
+         */
+        public function getAverageRating(): ActiveQuery
+        {
+            /**
+             * @var ActiveRecord $owner
+             */
+            $owner = $this->owner;
+            $pk = $owner->primaryKey()[ 0 ];
+            $query = $owner->hasOne($this->cacheModelName, [ $this->cacheModel->getLinkAttribute() => $pk ]);
+            return $query;
+        }
+        
+        /**
+         * Recalculate cache for current $owner model
+         *
+         * @return bool
+         */
+        public function recalculateRating(): bool
+        {
+            /**
+             * @var RatingCacheInterface $averageRating
+             */
+            $average = $this->getComments()
+                            ->joinWith('rating')
+                            ->select([ 'average' => 'avg(artbox_comment_rating.value)::float' ])
+                            ->scalar();
+            if (!$average) {
+                $average = 0;
+            }
+            $averageRating = $this->getAverageRating()
+                                  ->one();
+            if (!empty( $averageRating )) {
+                $averageRating->setValue($average);
+            } else {
+                /**
+                 * @var ActiveRecord         $owner
+                 * @var RatingCacheInterface $averageRating
+                 */
+                $owner = $this->owner;
+                $pk = $owner->primaryKey()[ 0 ];
+                $averageRating = \Yii::createObject(
+                    [
+                        'class'                               => $this->cacheModelName,
+                        $this->cacheModel->getLinkAttribute() => $this->owner->$pk,
+                    ]
+                );
+                $averageRating->setValue($average);
+            }
+            if ($averageRating->save()) {
+                return true;
+            } else {
+                return false;
+            }
+        }
+    }
+    
\ No newline at end of file
diff --git a/models/interfaces/RatingCacheInterface.php b/models/interfaces/RatingCacheInterface.php
new file mode 100644
index 0000000..870f1a9
--- /dev/null
+++ b/models/interfaces/RatingCacheInterface.php
@@ -0,0 +1,31 @@
+<?php
+    
+    namespace artweb\artbox\comment\models\interfaces;
+    
+    use yii\db\ActiveRecordInterface;
+
+    interface RatingCacheInterface extends ActiveRecordInterface
+    {
+        /**
+         * Get foreign key attribute name
+         *
+         * @return string
+         */
+        public function getLinkAttribute(): string;
+    
+        /**
+         * Get value
+         *
+         * @return float
+         */
+        public function getValue(): float;
+    
+        /**
+         * Set value
+         *
+         * @param float $value
+         *
+         * @return void
+         */
+        public function setValue(float $value);
+    }
\ No newline at end of file
diff --git a/readme b/readme
new file mode 100644
index 0000000..de800f6
--- /dev/null
+++ b/readme
@@ -0,0 +1,18 @@
+PHPDoc FOR CommentBehavior
+
+** From CommentBehavior **
+* @property string $cacheModelName
+* @property RatingCacheInterface $cacheModel
+* @property boolean $cacheRating
+* @property CommentModel[] $comments
+* @property RatingCacheInterface $averageRating
+* @method string getCacheModelName()
+* @method void setCacheModelName(string $value)
+* @method RatingCacheInterface getCacheModel()
+* @method void setCacheModel(RatingCacheInterface $value)
+* @method boolean getCacheRating()
+* @method void setCacheRating(bool $value)
+* @method ActiveQuery getComments()
+* @method ActiveQuery getAverageRating()
+* @method bool recalculateRating()
+** End CommentBehavior **
\ No newline at end of file
--
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