Add column to WooCommerce order email - Add an extra column to the WooCommerce order email. https://www.damiencarbery.com/2020/10/add-column-to-woocommerce-order-email/

email-order-details.php

<?php
/**
 * Order details table shown in emails.
 *
 * This template can be overridden by copying it to yourtheme/woocommerce/emails/email-order-details.php.
 *
 * HOWEVER, on occasion WooCommerce will need to update template files and you
 * (the theme developer) will need to copy the new files to your theme to
 * maintain compatibility. We try to do this as little as possible, but it does
 * happen. When this occurs the version of the template file will be bumped and
 * the readme will list any important changes.
 *
 * @see https://docs.woocommerce.com/document/template-structure/
 * @package WooCommerce\Templates\Emails
 * @version 3.7.0
 */

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 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>
				<!-- New column for product's categories. -->
				<th class="td" scope="col" style="text-align:<?php echo esc_attr( $text_align ); ?>;"><?php esc_html_e( 'Categories', 'woocommerce' ); ?></th>
				<th class="td" scope="col" style="text-align:<?php echo esc_attr( $text_align ); ?>;"><?php esc_html_e( 'Price', '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="3" 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() ) {
				?>
				<tr>
					<th class="td" scope="row" colspan="3" style="text-align:<?php echo esc_attr( $text_align ); ?>;"><?php esc_html_e( 'Note:', 'woocommerce' ); ?></th>
					<td class="td" style="text-align:<?php echo esc_attr( $text_align ); ?>;"><?php echo wp_kses_post( nl2br( wptexturize( $order->get_customer_note() ) ) ); ?></td>
				</tr>
				<?php
			}
			?>
		</tfoot>
	</table>
</div>

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

email-order-items.php

<?php
/**
 * Email Order Items
 *
 * This template can be overridden by copying it to yourtheme/woocommerce/emails/email-order-items.php.
 *
 * HOWEVER, on occasion WooCommerce will need to update template files and you
 * (the theme developer) will need to copy the new files to your theme to
 * maintain compatibility. We try to do this as little as possible, but it does
 * happen. When this occurs the version of the template file will be bumped and
 * the readme will list any important changes.
 *
 * @see     https://docs.woocommerce.com/document/template-structure/
 * @package WooCommerce\Templates\Emails
 * @version 3.7.0
 */

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>
		<!-- New cell listing product categories. -->
		<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_get_product_category_list( $item->get_product_id() ); ?>
		</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>
	</tr>
	<?php

	if ( $show_purchase_note && $purchase_note ) {
		?>
		<tr>
			<td colspan="3" 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; ?>

wc-extra-email-column.php

<?php
/*
Plugin Name: Add column to WooCommerce order email
Plugin URI: https://www.damiencarbery.com/2020/10/add-column-to-woocommerce-order-email/
Description: Add an extra column to the WooCommerce order email.
Author: Damien Carbery
Version: 0.1
WC tested up to: 4.6
 */


/*
// This is a hack solution. It is better to edit emails/email-order-items.php template file.
add_filter( 'woocommerce_email_order_item_quantity', 'dcwd_order_item_quantity', 10, 2 );
function dcwd_order_item_quantity( $qty_display, $item ) {
	return $qty_display . '<td class="td" style="vertical-align:middle; font-family: \'Helvetica Neue\', Helvetica, Roboto, Arial, sans-serif;">'.wc_get_product_category_list( $item->get_product_id() ) .'</td>';
}
*/


// Use the template file if it is under this plugin directory.
add_filter( 'wc_get_template', 'dcwd_get_woocommerce_template', 10, 5 );
function dcwd_get_woocommerce_template( $located, $template_name, $args, $template_path, $default_path ) {
	$plugin_dir_path = plugin_dir_path( __FILE__ );
	// $template_name will be something like 'emails/email-order-items.php' or 'single-product.php'
	if ( file_exists( $plugin_dir_path . $template_name ) ) {
		$located = $plugin_dir_path . $template_name;
	}
    
    return $located;
}