Wordpress Get value of hidden input field in functions.php - php

Question

I have a hidden input field, which I want to fetch in my functions.php, but I keep getting NULL as a return value.
Here is my code:
add_filter('woocommerce_add_cart_item_data', 'add_custom_field_data_to_cart', 10, 2 );
function add_custom_field_data_to_cart($cart_item_data, $product_id, $variation_id) {
$cart_item_data['myHiddenInput'] = $_POST['myHiddenInput'];
return $cart_item_data;
}
Can someone maybe tell me why I get NULL ?
EDIT
The hidden input field is on my archive-products.php of my woocommerce-shop
<input type="hidden" name="myHiddenInput" value="">
The value gets set by using javascript
UPDATE
What I want to achive is, that I have an archive-products page where all my products are listed. Now, above my products I have a tab-menu with the next 5 days of the week. So I click the tab "Wednesday 19." the value of the hidden input gets the date of the active menu-tab:
<input type="hidden" name="chosenDate" value="2018-09-19">
Now I add a product to my cart. Then I click the menu-tab "Friday 21." - the value of the hidden filed gets updated -> I add a product to the cart.
Now when I go to my cart page - I want the products to have the dates listed when they will get delivered (the dates from the menu-tab when they were added)

Answer 1

as #LoicTheAztec Said
You can't pass anything custom from any archive page via ajax add to cart button as if you look to the source code of Ajax add to cart… There is no possible additional arguments or hooks. So you will need to build your own Ajax add to cart functionality, which is something huge and complicated. So your hooked function woocommerce_add_cart_item_data will have no effect
so the best logic is to use Javascript to achieve your goal and you can do it like the below solution:
First Lets add those value inside the add to cart button as an attribute instead of input tag.
for that we are going to us woocommerce_loop_add_to_cart_args hook as follow:
add_filter( 'woocommerce_loop_add_to_cart_args', 'change_item_price', 10, 2 );
function change_item_price( $args, $product ) {
$args['attributes'] = $args['attributes'] + [ 'data-chosen-date' => '2018-09-19' ];
return $args;
}
you can add as many attribute as you want and modify the value through your script and then store those value when the user click add to cart intro session storage and then in the cart page you can get those values and append them to cart table so for example:
add_action( 'wp_footer', 'script' );
function script() {
if ( is_shop() ) {?>
<script>
document.body.addEventListener('click', add_to_cart);
function add_to_cart(e) {
if (e.target.classList.contains('add_to_cart_button')) {
let val = e.target.getAttribute('data-chosen-date');
let product_id = e.target.getAttribute('data-product_id');
sessionStorage.setItem(product_id, val);
}
}
</script>
<?php
}
if ( is_cart() ) {
?>
<script>
var items = document.querySelectorAll("td");
items.forEach(function (item, index) {
if (item.classList.contains('product-remove')) {
var id = item.childNodes[1].getAttribute('data-product_id');
if (sessionStorage.getItem(id)) {
var textnode = document.createElement('p');
textnode.innerHTML = sessionStorage.getItem(id);
item.nextElementSibling.nextElementSibling.appendChild(textnode)
}
}
}); </script>
<?php
}
}
output :
The Date after the item link in the cart table has been retrieved from our storage session and each value we stored is maped with the product id as key in our storage session so we can have different value for each product.