How to programmatically set a multiselect attribute value to a product in Magento 2?

Question

I'm having trouble setting values to a multiselect type attribute for a product programatically.

Example attribute: material

Example values: cotton & polyester

Please note that both attribute and option values are created from the backend.

This is what I have tried so far:

$product = $objectManager->create('Magento\Catalog\Model\Product');
$sku = '1234';
$product_id = $product->getIdBySku($sku);
if ($product_id) {
    $product->load($product_id);
    $attribute_values = array('cotton','polyester');
    $product_resource = $product->getResource();
    $attribute_code = 'material';
    $attribute = $product_resource->getAttribute($attribute_code);
    if ($attribute->usesSource()) {
        foreach ($attribute_values as $attribute_value) {
            $attribute_option_ids[] = $attribute->getSource()->getOptionId($attribute_value);
        }
        $product->setData($attribute_code, $attribute_option_ids); // attempt 1
        //$product->setData($attribute_code, array($attribute_option_ids)); // attempt 2
        //$product->getResource()->saveAttribute($product, $attribute_code); // attempt 3 with combining attempt 1
    }
    $product->save();
}

The end result is that no values are set for the material attribute for product 1234.

Any ideas what I'm doing wrong?

Answer 1

It seems that my original code is working, but the problem was that I had 2 store views.

When setting attributes like this, it required an additional line of code:

$product->setStoreId(0); // store_id = 0 is the default store

Before saving the product.

The attributes were actually being saved for the main store view (my store has multiple store views), but the "default product data" (default view) remained unchanged.

The "attempt 1" from the code in my question was the correct way of setting this data.

Answer 2

Just to it like below code :

Inject this below class in your construct:

protected $productRepository;
public function __construct(
    \Magento\Catalog\Api\ProductRepositoryInterface $productRepository
) {
    $this->productRepository = $productRepository;
}

And use this below code :

$product = $this->productRepository->getById('product-id');
$product->setData('attribute-code', 'attribute-value');
$this->productRepository->save($product);

Object Manager :

$objectManager = \Magento\Framework\App\ObjectManager::getInstance(); 

$product = $objectManager->get('\Magento\Catalog\Model\ProductRepository')->getById('product-id');
$product->setData('attribute-code', 'attribute-value');
$this->productRepository->save($product);