WooCommerce Button to Clear Cart, Add One Item and go to Checkout - php

Question

I need a button on a unique landing page which does this:
clears the cart
adds a specific Item to the cart
go directly to checkout
(disable or hide menue-bar in checkout) <-I tried this with JavaScript but failed
I got a button which calls the link: https://www.snoooze.co/?add-to-cart= 12374
And then this snippet in my "functions.php"
add_filter ('woocommerce_add_to_cart_redirect', 'woo_redirect_to_checkout');
function woo_redirect_to_checkout() {
global $woocommerce;
$woocommerce->cart->empty_cart();
$checkout_url = WC()->cart->get_checkout_url();
return $checkout_url; }
The problem is that if I add the item in my function with add_to_Cart() it does this every time I want to add it manually in the shop, not just if I click on the button on the landing page.
I see that I have to assign the function to the button in some way, so doesn't get called on other sites, but how?
Any help please.

Answer 1

First you need a custom button embedded in an form. So here is a simple shortcode that you can use in a content editor or in php:
// Shortcode: Special button "add-to-cart" with form
function special_button() {
return '<form method="post" action="">
<button type="submit" class="button" name="add_to_cart_special">Special add to cart</button>
</form>';
}
add_shortcode( 'special_button', 'special_button' );
// Usage: [special_button]
// or for php: echo do_shortcode("[special_button]");
And this custom hooked function that will be triggered when you press that custom button. It will:
empty cart,
add product 12374 to cart
redirect to checkout
display a custom notice in checkout page (optionally)
The code:
// Special add to cart (empty cart before and redirect to checkout)
add_action( 'template_redirect', 'special_add_to_cart' );
function special_add_to_cart() {
if ( isset($_POST['add_to_cart_special']) ){
WC()->cart->empty_cart();
WC()->cart->add_to_cart( 12374 );
wc_add_notice( __('this product X has been added to cart'), 'notice' );
wp_redirect( wc_get_checkout_url() );
exit();
}
}
ALL Code goes in function.php file of your active child theme (or active theme).
Tested and works.
But to disable or hide your "menu bar" in checkout, I really don't know… This should be another new question with more details…