Woocommerce custom field on emails outputs 'Array'

Question

I'm trying to add a custom email field in Woocommerce.

Code to add the pickup date field to checkout:

// ----------------------------------------------------------------------------
// Pickup Date Field
// ----------------------------------------------------------------------------

add_action( 'woocommerce_after_order_notes', 'gfm_pickup_date_field' );

function gfm_pickup_date_field( $checkout ) {

    // The pickup delay is the minimum number of days between when an order is placed
    // and when it can be picked up.

    $pickup_delay = gfm_get_min_pickup_delay();

    echo '<div id="gfm_pickup_date_field"><h3>' . __('Pickup') . '</h3>';

    woocommerce_form_field( 'gfm_pickup_date', array(
        'type'          => 'text',
        'class'         => array('gfm_pickup_date-class form-row-wide'),
        'label'         => __('Pickup Date'),
        'placeholder'   => __('month/day/year'),
        ), $checkout->get_value( 'gfm_pickup_date' ));

    echo '</div>';
    echo "<script type='text/javascript'>
            jQuery(document).ready(function() {
                jQuery('#gfm_pickup_date').datepicker({
                    dateFormat : 'mm/dd/yy',
                    minDate: {$pickup_delay}
                });
            });
            </script>";
}

Code to save pickup date with order:

// ----------------------------------------------------------------------------
// Save Pickup Date with Order
// ----------------------------------------------------------------------------

add_action( 'woocommerce_checkout_update_order_meta', 'gfm_checkout_field_update_order_meta' );

function gfm_checkout_field_update_order_meta( $order_id ) {

    // Save pickup date if user chose to pickup the order

    if (WC()->session->get('chosen_shipping_methods')[0] == 'local_pickup') {
        update_post_meta( $order_id, 'gfm_pickup_date', sanitize_text_field( $_POST['gfm_pickup_date'] ) );
    }
}

And code to send the emails:

// ----------------------------------------------------------------------------
// Add the Pickup Date to Emails
// ----------------------------------------------------------------------------

add_filter('woocommerce_email_order_meta_keys', 'gfm_order_meta_keys');

function gfm_order_meta_keys( $keys ) {
    $keys[] = 'gfm_pickup_date';
    return $keys;
}



  function gfm_enqueue_scripts() {

      wp_enqueue_style( 'jquery-ui-css', get_template_directory_uri() . '/jquery-ui-1.11.4/jquery-ui.min.css');

      wp_enqueue_script( 'jquery-ui-js', get_template_directory_uri() . '/jquery-ui-1.11.4/jquery-ui.min.js', array('jquery'));

  }



  add_action( 'wp_enqueue_scripts', 'gfm_enqueue_scripts' );

When I run this code, it does the following:

Answer 1

You can try with:

function gfm_order_meta_keys( $keys ) {

    $new_keys = array('Pickup date'=>'gfm_pickup_date');
    // if the action is used by another plugin, we merge keys into one array
    $keys = array_merge($keys, $new_keys);

    return $keys;
}