Magento 2 How to add simple product to Grouped product

Question

I want to add a simple product to a grouped product. I tried a lot of different approaches, including direct database modifications, all without success. I'm guessing it should be something like this.

$objectManager = \Magento\Framework\App\ObjectManager::getInstance();
    $product = $objectManager->create('Magento\Catalog\Model\Product')->load($groupedID); // Load Configurable Product
    $associatedProductIds = array($simpleID); //Product Ids Of Associated Products
    $product->setAssociatedProductIds($associatedProductIds);// Setting Associated Products
    $product->save();

the above gives no error. but also does not create a link.

Answer 1

I haven’t found a permanent solution for this problem yet, but for now I have used a direct SQL connection as described here: https://magento.stackexchange.com/a/105148/15548

$q = $this->_objectManager->get('\Magento\Framework\App\ResourceConnection');
$q->getConnection('core_write')->query("insert into catalog_product_link (linked_product_id, product_id,link_type_id) values (".$linked_product_id.",".$product_id.",".$link_type_id.")");

Where $link_type_id is 3 as this is the ID for grouped products.

Not the best way but for now It works. I'll update this when I find a better way.