Add custom attributes to the WooCommerce Checkout Add-ons form elements

wc-coa-add-attributes.php

<?php // only copy this line if needed!


/**
 * Add attributes to our checkout fields.
 *
 * @param array $checkout_fields the checkout field data
 */
function wc_add_checkout_add_ons_attributes( $checkout_fields ) {

    $add_on_id = 'abc123'; // change to your add-on id

    if ( isset( $checkout_fields['add_ons'][ 'wc_checkout_add_ons_' . $add_on_id ] ) ) {

        $checkout_fields['add_ons'][ 'wc_checkout_add_ons_' . $add_on_id ]['maxlength']   = "300";
        $checkout_fields['add_ons'][ 'wc_checkout_add_ons_' . $add_on_id ]['description'] = "Please add no more than 300 characters.";
        // Adds a maximum character length + description to this add on
    }

    // repeat for each add-on
    $add_on_id = 'abc124'; // change to your add-on id

    if ( isset( $checkout_fields['add_ons'][ 'wc_checkout_add_ons_' . $add_on_id ] ) ) {

		$checkout_fields['add_ons'][ 'wc_checkout_add_ons_' . $add_on_id ]['maxlength']   = "140";
        $checkout_fields['add_ons'][ 'wc_checkout_add_ons_' . $add_on_id ]['placeholder'] = "My custom placeholder";
        // Add a maximum length and placeholder
    }

    return $checkout_fields;
}
add_filter( 'woocommerce_checkout_fields', 'wc_add_checkout_add_ons_attributes', 20 );

Hey Beka, is there any documentation on adding validation to a field or is the "validate" attribute something other than a bool or a range, etc?

For example:
$checkout_fields['add_ons'][ 'wc_checkout_add_ons_' . $add_on_id ]['validate'] = $validate;

Can the string be called and validate if field was "valid"? I am mostly looking for a guide to the attributes but I will inevitably end of reverse engineering the plugin functions.

This code works (note change to the add_on_id):

// Add attributes to our checkout fields
function wc_add_checkout_add_ons_attributes( $checkout_fields ) {

$add_on_id = 3; // change 3 to your add-on id

if ( isset( $checkout_fields['add_ons'][ 'wc_checkout_add_ons_' . $add_on_id ] ) ) {
    $checkout_fields['add_ons'][ $add_on_id ]['maxlength']   = "300";
    $checkout_fields['add_ons'][ $add_on_id ]['description']   = "Please add no more than 300 characters.";
    //Adds a maximum character length + description to this add on
}

// repeat for each add-on
$add_on_id = 7; // change 7 to your add-on id

if ( isset( $checkout_fields['add_ons'][ $add_on_id ] ) ) {
    $checkout_fields['add_ons'][ $add_on_id ]['maxlength']   = "140";
    $checkout_fields['add_ons'][ $add_on_id ]['placeholder'] = "My custom placeholder";
    //Add a maximum length and placeholder
}

return $checkout_fields;

}
add_filter( 'woocommerce_checkout_fields', 'wc_add_checkout_add_ons_attributes', 20 );

Hey,
I used the code as follow, but it is not working and it returns an error on checkout page :

ERROR :
Warning: Use of undefined constant f5472d2 - assumed 'f5472d2' (this will throw an Error in a future version of PHP) in /homepages/2/d660419233/htdocs/clickandbuilds/PremierMoment/wp-content/themes/flatsome-child/functions.php on line 25

OUR CODE, in functions.php :
function wc_add_checkout_add_ons_attributes( $checkout_fields ) {

$add_on_id = f5472d2; // I also tried with "f5472d2", the error message disapear, but the code is still not working

if ( isset( $checkout_fields['add_ons'][ 'wc_checkout_add_ons_' . $add_on_id ] ) ) {
    $checkout_fields['add_ons'][ 'wc_checkout_add_ons_' . $add_on_id ]['maxlength']   = "250";
    $checkout_fields['add_ons'][ 'wc_checkout_add_ons_' . $add_on_id ]['placeholder'] = "250 characters max";
    //Add a maximum length and placeholder
}

return $checkout_fields;

}
add_filter( 'woocommerce_checkout_fields', 'wc_add_checkout_add_ons_attributes', 20 );

Any help ?
Many thanks ! :)