WooCommerce with Yoast SEO plugin is the best combination for your online store to have a good SEO score. Yoast SEO provides a primary category feature that helps you point out which product category is more important for a particular post if you select multiple product categories for the product.
As we have the primary product category for the product selected, it’s better to show products of the same primary product category as related products on the product detail page. Add below code in functions.php file of your active theme to show products from the same Yoast primary category as related products in the WooCommerce.
/**
* Show related products from Yoast Primary Category in WooCommerce
*/
add_filter( 'woocommerce_get_related_product_cat_terms', function( $terms, $product_id ) {
if ( function_exists( 'yoast_get_primary_term_id' ) ) {
$primary_term_product_id = yoast_get_primary_term_id( 'product_cat', $product_id );
if ( $primary_term_product_id ) {
return array( $primary_term_product_id );
}
}
return $terms;
}, 10, 2 );
