WooCommerce - Link to add a qty of product

woocomerce-link-to-add-product-qty.php

<?php

function quick_cart_5_horus(){
    global $woocommerce;
    $product_id = sanitize_text_field( $_POST['product_id'] );
    // Be sure cart is empty from previous add to cart
    WC()->cart->empty_cart(); 
    // Addding the product by product ID
    WC()->cart->add_to_cart( $product_id );
    // Getting the cart item key
    foreach ( $woocommerce->cart->get_cart() as $cart_item_key => $cart_item ) {
       
    }
    // Setting product qty by $cart_item_key
    WC()->cart->set_quantity(  $cart_item_key, 5 );
    // Cart URL to redirect user from front end 
    $checkout_url = $woocommerce->cart->get_checkout_url();
    // Echo URL to front
    echo $checkout_url;

    wp_die();
}
// bind ajax call to callback function
add_action( 'wp_ajax_quick_cart_5_horus', 'quick_cart_5_horus' );
// Print ajax js
add_action("wp_footer","print_set_cart_qty_js",100);
function print_set_cart_qty_js(){ ?>
<script>
(function ($) {
$('.quick-cart').click(function(){
           //var product_id= $(this).data('quick_id');
            var loading_type = $(this).data('loading_type');
  
            $("#"+loading_type).show("slow");
            $.ajax({
                type: "POST",
                url: "<?php echo get_site_url() ?>/wp-admin/admin-ajax.php",
                data: {
                    'action': 'quick_cart_5_horus',
                    'product_id': 26
                    
                },
                success: function (response) {
                   window.location.assign(response)
                }
            });

        });
  })(jQuery);
</script>
<?php
}
// This article has a direct URL from Woo's core to add variations, didn't test it  it http://www.remicorson.com/add-woocommerce-variable-product-with-variations-to-cart/