public function relationList($relationName, $index = 'id', $name = null)
    {
        $model = $this->owner;
        /** @var ActiveRecord $class */
        $class = $model->getRelation($relationName)->modelClass;
        $item = new $class();
        /** @var \yii\db\ActiveQuery $relation */
        $relation = method_exists($item, 'search')
            ? $item->search([])
            : $class::find();
        $name = $name ? : static::getNameAttribute($model, $relationName);
        $result = $relation->select($name)
            ->orderBy($name)
            ->indexBy($index)
            ->column();
        return $result;
    }