Excluding Products

In order to exclude certain products from being indexed, you will need to override the Nosto product model and flag it to be excluded.

Start by reading how to extend Nosto module and how to alter Nosto product data.

File app/code/My/Nosto/Observer/Product/Load.php

<?php

namespace My\Nosto\Observer\Product;

use Magento\Framework\Event\Observer;
use Magento\Framework\Event\ObserverInterface;

class Load implements ObserverInterface
{
    public function __construct()
    {
    }

    /**
     * Observer for "nosto_product_load_before" event
     *
     * @param Observer $observer
     * @return void
     */
    public function execute(Observer $observer)
    {
        /* @var $product \NostoProduct */
        $product = $observer->getProduct();
        $modelFilter = $observer->getData('modelFilter');

        // If the product meets your desired criteria, set valid to false
        foreach ($product->getCategories() as $category) {
            if ($category === 'category') {
                $modelFilter->setValid(false);
            }
        }
    }
}