我想在barcode/ISBN的电子邮件订单确认邮件中的价格旁边添加一列。
我正在使用插件：WooCommerce Barcode & ISBN
每种产品的外观如下所示：

以及后端的每一个产品内部：

我已经有了列和所有的东西，我只是不知道如何在PHP中“获取”条形码/ISBN。
我在email-order-details中的代码（创建/添加列的位置）：

defined( 'ABSPATH' ) || exit;

$text_align = is_rtl() ? 'right' : 'left';

do_action( 'woocommerce_email_before_order_table', $order, $sent_to_admin, $plain_text, $email ); ?>

<h2>
    <?php
    if ( $sent_to_admin ) {
        $before = '<a class="link" href="' . esc_url( $order->get_edit_order_url() ) . '">';
        $after  = '</a>';
    } else {
        $before = '';
        $after  = '';
    }
    /* translators: %s: Order ID. */
    echo wp_kses_post( $before . sprintf( __( '[Order #%s]', 'woocommerce' ) . $after . ' (<time datetime="%s">%s</time>)', $order->get_order_number(), $order->get_date_created()->format( 'c' ), wc_format_datetime( $order->get_date_created() ) ) );
    ?>
</h2>

<div>
                    <h3 style="text-align:<?php echo esc_attr( $text_align ); ?>;"><?php esc_html_e( 'Ordermeddelande/Önskat leveransdatum:
', 'woocommerce' ); ?></h3>
                    <p style="text-align:<?php echo esc_attr( $text_align ); ?>;"><?php echo wp_kses_post( nl2br( wptexturize( $order->get_customer_note() ) ) ); ?></p>
                </div>

<div style="margin-bottom: 40px;">
    <table class="td" cellspacing="0" cellpadding="6" style="width: 100%; font-family: 'Helvetica Neue', Helvetica, Roboto, Arial, sans-serif;" border="1">
        <thead>
            <tr>
                <th class="td" scope="col" style="text-align:<?php echo esc_attr( $text_align ); ?>;"><?php esc_html_e( 'Product', 'woocommerce' ); ?></th>
                <th class="td" scope="col" style="text-align:<?php echo esc_attr( $text_align ); ?>;"><?php esc_html_e( 'Quantity', 'woocommerce' ); ?></th>
                <th class="td" scope="col" style="text-align:<?php echo esc_attr( $text_align ); ?>;"><?php esc_html_e( 'Price', 'woocommerce' ); ?></th>
                <th class="td" scope="col" style="text-align:<?php echo esc_attr( $text_align ); ?>;"><?php esc_html_e( 'á pris', 'woocommerce' ); ?></th>
                <th class="td" scope="col" style="text-align:<?php echo esc_attr( $text_align ); ?>;"><?php esc_html_e( 'Rek ut / Streckkod', 'woocommerce' ); ?></th>

            </tr>
        </thead>
        <tbody>
            <?php
            echo wc_get_email_order_items( // phpcs:ignore WordPress.Security.EscapeOutput.OutputNotEscaped
                $order,
                array(
                    'show_sku'      => $sent_to_admin,
                    'show_image'    => false,
                    'image_size'    => array( 32, 32 ),
                    'plain_text'    => $plain_text,
                    'sent_to_admin' => $sent_to_admin,
                )
            );
            ?>
        </tbody>
        <tfoot>
            <?php
            $item_totals = $order->get_order_item_totals();

            if ( $item_totals ) {
                $i = 0;
                foreach ( $item_totals as $total ) {
                    $i++;
                    ?>
                    <tr>
                        <th class="td" scope="row" colspan="4" style="text-align:<?php echo esc_attr( $text_align ); ?>; <?php echo ( 1 === $i ) ? 'border-top-width: 4px;' : ''; ?>"><?php echo wp_kses_post( $total['label'] ); ?></th>
                        <td class="td" style="text-align:<?php echo esc_attr( $text_align ); ?>; <?php echo ( 1 === $i ) ? 'border-top-width: 4px;' : ''; ?>"><?php echo wp_kses_post( $total['value'] ); ?></td>
                    </tr>
                    <?php
                }
            }
            if ( $order->get_customer_note() ) {
                ?>
                
                <?php
            }
            ?>
        </tfoot>
    </table>
</div>

<?php do_action( 'woocommerce_email_after_order_table', $order, $sent_to_admin, $plain_text, $email ); ?>

在email-order-items里面（我猜我应该把条形码/ISBN代码放在那里），现在它正在显示任何带有条形码/ISBN代码的东西：

defined( 'ABSPATH' ) || exit;

$text_align  = is_rtl() ? 'right' : 'left';
$margin_side = is_rtl() ? 'left' : 'right';

foreach ( $items as $item_id => $item ) :
    $product       = $item->get_product();
    $sku           = '';
    $purchase_note = '';
    $image         = '';

    if ( ! apply_filters( 'woocommerce_order_item_visible', true, $item ) ) {
        continue;
    }

    if ( is_object( $product ) ) {
        $sku           = $product->get_sku();
        $purchase_note = $product->get_purchase_note();
        $image         = $product->get_image( $image_size );
    }

    ?>
    <tr class="<?php echo esc_attr( apply_filters( 'woocommerce_order_item_class', 'order_item', $item, $order ) ); ?>">
        <td class="td" style="text-align:<?php echo esc_attr( $text_align ); ?>; vertical-align: middle; font-family: 'Helvetica Neue', Helvetica, Roboto, Arial, sans-serif; word-wrap:break-word;">
        <?php

        // Show title/image etc.
        if ( $show_image ) {
            echo wp_kses_post( apply_filters( 'woocommerce_order_item_thumbnail', $image, $item ) );
        }

        // Product name.
        echo wp_kses_post( apply_filters( 'woocommerce_order_item_name', $item->get_name(), $item, false ) );

        // SKU.
        if ( $show_sku && $sku ) {
            echo wp_kses_post( ' (#' . $sku . ')' );
        }

        // allow other plugins to add additional product information here.
        do_action( 'woocommerce_order_item_meta_start', $item_id, $item, $order, $plain_text );

        wc_display_item_meta(
            $item,
            array(
                'label_before' => '<strong class="wc-item-meta-label" style="float: ' . esc_attr( $text_align ) . '; margin-' . esc_attr( $margin_side ) . ': .25em; clear: both">',
            )
        );

        // allow other plugins to add additional product information here.
        do_action( 'woocommerce_order_item_meta_end', $item_id, $item, $order, $plain_text );

        ?>
        </td>
        <td class="td" style="text-align:<?php echo esc_attr( $text_align ); ?>; vertical-align:middle; font-family: 'Helvetica Neue', Helvetica, Roboto, Arial, sans-serif;">
            <?php
            $qty          = $item->get_quantity();
            $refunded_qty = $order->get_qty_refunded_for_item( $item_id );

            if ( $refunded_qty ) {
                $qty_display = '<del>' . esc_html( $qty ) . '</del> <ins>' . esc_html( $qty - ( $refunded_qty * -1 ) ) . '</ins>';
            } else {
                $qty_display = esc_html( $qty );
            }
            echo wp_kses_post( apply_filters( 'woocommerce_email_order_item_quantity', $qty_display, $item ) );
            ?>
        </td>
        <td class="td" style="text-align:<?php echo esc_attr( $text_align ); ?>; vertical-align:middle; font-family: 'Helvetica Neue', Helvetica, Roboto, Arial, sans-serif;">
            <?php echo wp_kses_post( $order->get_formatted_line_subtotal( $item ) ); ?>
        </td>
        <td class="td" style="text-align:<?php echo esc_attr( $text_align ); ?>; vertical-align:middle; font-family: 'Helvetica Neue', Helvetica, Roboto, Arial, sans-serif;">
            <?php echo wc_price( $order->get_item_total( $item, false, true ), array( 'currency' => $order->get_order_currency() ) ); ?>
        </td>
        <td class="td" style="text-align:<?php echo esc_attr( $text_align ); ?>; vertical-align:middle; font-family: 'Helvetica Neue', Helvetica, Roboto, Arial, sans-serif;">
        <?php echo get_post_meta( get_the_ID(), 'barcode', true ); ?>
        <?php echo get_post_meta( get_the_ID(), 'ISBN', true ); ?>
        </td>
    </tr>
    <?php

    if ( $show_purchase_note && $purchase_note ) {
        ?>
        <tr>
            <td colspan="2" style="text-align:<?php echo esc_attr( $text_align ); ?>; vertical-align:middle; font-family: 'Helvetica Neue', Helvetica, Roboto, Arial, sans-serif;">
                <?php
                echo wp_kses_post( wpautop( do_shortcode( $purchase_note ) ) );
                ?>
            </td>
        </tr>
        <?php
    }
    ?>

<?php endforeach; ?>

如何获得正确的PHP代码以在电子邮件中显示ISBN和barcode？