yii\rbac\DbManager::getChildren PHP Method

    public function getChildren($name)
    {
        $query = (new Query())->select(['name', 'type', 'description', 'rule_name', 'data', 'created_at', 'updated_at'])->from([$this->itemTable, $this->itemChildTable])->where(['parent' => $name, 'name' => new Expression('[[child]]')]);
        $children = [];
        foreach ($query->all($this->db) as $row) {
            $children[$row['name']] = $this->populateItem($row);
        }
        return $children;
    }

 /** @inheritdoc */
 public function init()
 {
     parent::init();
     $this->manager = \Yii::$app->authManager;
     if ($this->item instanceof Item) {
         $this->name = $this->item->name;
         $this->description = $this->item->description;
         $this->children = array_keys($this->manager->getChildren($this->item->name));
         if ($this->item->ruleName !== null) {
             $this->rule = get_class($this->manager->getRule($this->item->ruleName));
         }
     }
 }