Multi select product attribute value not saving in magento2

Question

I have created a script file to update the multi select attribute for the products

here is my code

 <?php

 error_reporting(E_ALL);
 use \Magento\Framework\App\Bootstrap;
 require __DIR__ . '/app/bootstrap.php';
 $bootstrap = Bootstrap::create(BP, $_SERVER);
 $obj = $bootstrap->getObjectManager(); 
 $state = $obj->get('Magento\Framework\App\State');
 $state->setAreaCode('frontend');

 $resource = $obj->get('Magento\Framework\App\ResourceConnection');
 $connection = $resource->getConnection();
 $sql = "SELECT `e`.*  FROM `catalog_product_entity` AS `e` WHERE (`e`.`attribute_set_id` = '19') limit 3";
 $result = $connection->query($sql);
 $resultCollection = $result->fetchAll();
 $objectManager = \Magento\Framework\App\ObjectManager::getInstance();
 foreach($resultCollection as $item){
  $productId = $item['entity_id'];  
  $product = $objectManager->get('Magento\Catalog\Model\ProductFactory')->create()->load($productId);
  $attrCode = 'pod_paper_size';
  $sourceModel = $product->getResource()->getAttribute('pod_paper_size')->getSource();
  $valuesText = explode(',', 'Extra_Small,Medium,Small,Large');

  $valuesIds = array_map(array($sourceModel, 'getOptionId'), $valuesText);

  $product->setData('pod_paper_size', $valuesIds);
  $product->setVisibility(4);
  $product->save();

}

Can anyone update me what is the correct code to update the multi-select attribute value pro grammatically, Thanks in Advance!!

Answer 1

If it is one time script, You should use Magento Update Script.
Instead of using sql, You can get product attached to specific atribut set using Search criteria https://alanstorm.com/magento_2_understanding_object_repositories/

Instead of using objectManager, use constructor.

On product You should be able to set values for multiselect as array or string ( imploded array) - using values Id.