How can I add to the order meta from input boxes? - php

Question

I'm creating a plugin for wordpress and woocommerce. In my plugin, I've inserted an input box above the checkout form using code using 'woocommerce_before_checkout_form'. On completion of the order, I'd like to be able to add the value from that input to the order's meta data. to that end, I created this code in the functions.php file of my plugin:
add_action( 'woocommerce_checkout_update_order_meta', 'add_input_meta', 1, 2 );
function add_input_meta( $order_id, $posted ) {
$inputsData = $_POST['InputBox'];
update_post_meta( $order_id, 'my_key', $inputsData);
}
The problem is, it returns NULL every time. I created the code below to see what the value of $_POST and it came up with 'array(0) { }'
function debugthing( $content ) {
$content .=var_dump($_POST);
return $content;
die();
}
add_filter( 'the_content', 'debugthing' );
I've exhausted every idea I could ahve about what is causing this. can anyone help?
$_POST, even php://input return an empty array or absolutely nothing.

Answer 1

woocommerce_before_checkout_form is not the right hook to add input fields. For this hook is outside the form. This explains why you are getting null on $_POST
use any of the hook inside the <form in form-checkout.php#L35
call woocommerce_form_field to add fields...
next is you need to hook inside process_checkout() function.
a. woocommerce_after_checkout_validation - for input validations...
b. woocommerce_checkout_order_processed - order created, do your meta data addition...
// add form fields
add_action( 'woocommerce_checkout_before_customer_details', 'woocommerce_checkout_before_customer_details' );
function woocommerce_checkout_before_customer_details() {
$args = array(
'type' => 'text',
'label' => 'My Custom field',
'description' => 'This is custom field',
'placeholder' => '',
'required' => true,
);
woocommerce_form_field( 'InputBox' , $args ); // you can call woocommerce_form_field as many as you want...
}
// validate your form field(s)
add_action( 'woocommerce_after_checkout_validation', 'woocommerce_after_checkout_validation' );
function woocommerce_after_checkout_validation() {
// $_POST['InputBox'] will be visible here...
// do your validations here... forget this hook if you don't need to validate...
// wc_add_notice( __( 'Invalid message!', 'woocommerce' ), 'error' );
// call wc_add_notice if you want to invalidate the form.
}
add_action( 'woocommerce_checkout_order_processed', 'woocommerce_checkout_order_processed' );
function woocommerce_checkout_order_processed( $order_id ) {
// we now have $order_id, you can now add your meta data....
}

Answer 2

change your hook priority like this.
add_action( 'woocommerce_checkout_update_order_meta', 'add_input_meta', 99, 2 );