Example Code for hiding products for Commerce Stock.

gistfile1.txt

<?php
/**
 * @file mymodule.module
 * Includes drupal hooks for module.
 */
use Drupal\mymodule\PremiumContentAccessControlHandler;
/**
 * Implements hook_entity_type_alter().
 */
function mymodule_entity_type_alter(array &$entity_types) {
  $entity_types['commerce_product']->setHandlerClass('access', ProductStockAccessControlHandler::class);
  $entity_types['commerce_product_variation']->setHandlerClass('access', ProductVariationStockAccessControlHandler::class);
}

<?php
namespace Drupal\mymodule;
use Drupal\Core\Access\AccessResult;
use Drupal\Core\Field\FieldDefinitionInterface;
use Drupal\Core\Field\FieldItemListInterface;
use Drupal\Core\Session\AccountInterface;
use Drupal\node\NodeAccessControlHandler;
/**
 * Defines the custom access control handler for the node entity type.
 */
class StockAccessControlHandler extends NodeAccessControlHandler {
  /**
   * {@inheritdoc}
   */
  protected function checkFieldAccess(
    $operation,
    FieldDefinitionInterface $field_definition,
    AccountInterface $account,
    FieldItemListInterface $items = NULL
  ) {
    /*
     * Allow specific roles to access premium content.
     */
    $hasAccess = FALSE;
    if ($field_definition->getName() === 'field_stock_level') {
      if ($operation == 'view') {

        if (!($variation->stock_level->value > 0) && !$account->hasRole('administrator')) {
          return AccessResult::forbidden();
        }

        return AccessResult::allowedIfHasPermission(
          $account,
          'view premium content'
        );
      }
    }
    // Run parent's checkFieldAccess.
    return parent::checkFieldAccess(
      $operation,
      $field_definition,
      $account,
      $items
    );
  }
}


<?php
namespace Drupal\mymodule;
use Drupal\Core\Access\AccessResult;
use Drupal\Core\Field\FieldDefinitionInterface;
use Drupal\Core\Field\FieldItemListInterface;
use Drupal\Core\Session\AccountInterface;
use Drupal\node\NodeAccessControlHandler;
/**
 * Defines the custom access control handler for the node entity type.
 */
class StockAccessControlHandler extends NodeAccessControlHandler {
  /**
   * {@inheritdoc}
   */
  protected function checkFieldAccess(
    $operation,
    FieldDefinitionInterface $field_definition,
    AccountInterface $account,
    FieldItemListInterface $items = NULL
  ) {
    /*
     * Allow specific roles to access premium content.
     */
    $hasAccess = FALSE;
    if ($field_definition->getName() === 'field_premium_content') {
      if ($operation == 'view') {

        foreach($entity->variations as $variation) {
          if ($field_definition->getName() === 'field_stock_level') {
            if ($variation->field_stock_level->value > 0) {
              $hasAccess = true;
              break;
            }
          }
        }

        if (!$hasAccess && !$account->hasRole('administrator')) {
          return AccessResult::forbidden();
        }

        return AccessResult::allowedIfHasPermission(
          $account,
          'view premium content'
        );
      }
    }
    // Run parent's checkFieldAccess.
    return parent::checkFieldAccess(
      $operation,
      $field_definition,
      $account,
      $items
    );
  }
}