Adds a GTIN column to the WooCommerce Products table, making it sortable and searchable.

add-gtin-column-to-products-list.php

/**
 * Add GTIN Column to WooCommerce Products List Table
 *
 * Adds a sortable, searchable GTIN column to Products > All Products.
 */

// Add GTIN column to products list (positioned after SKU).
add_filter( 'manage_edit-product_columns', function( $columns ) {
	// Find SKU position and insert after it.
	$sku_position = array_search( 'sku', array_keys( $columns ), true );

	if ( false !== $sku_position ) {
		return array_slice( $columns, 0, $sku_position + 1, true )
			+ array( 'gtin' => __( 'GTIN', 'woocommerce' ) )
			+ array_slice( $columns, $sku_position + 1, null, true );
	}

	// Fallback: Insert after Name if SKU doesn't exist.
	$name_position = array_search( 'name', array_keys( $columns ), true );
	if ( false !== $name_position ) {
		return array_slice( $columns, 0, $name_position + 1, true )
			+ array( 'gtin' => __( 'GTIN', 'woocommerce' ) )
			+ array_slice( $columns, $name_position + 1, null, true );
	}

	$columns['gtin'] = __( 'GTIN', 'woocommerce' );
	return $columns;
}, 20 );

// Populate GTIN column with data.
add_action( 'manage_product_posts_custom_column', function( $column_name, $post_id ) {
	if ( 'gtin' !== $column_name ) {
		return;
	}

	$product = wc_get_product( $post_id );

	if ( ! $product ) {
		echo '<span class="na">&ndash;</span>';
		return;
	}

	$gtin = $product->get_global_unique_id();
	echo $gtin ? esc_html( $gtin ) : '<span class="na">&ndash;</span>';
}, 10, 2 );

// Make GTIN column sortable.
add_filter( 'manage_edit-product_sortable_columns', function( $columns ) {
	$columns['gtin'] = 'by_gtin';
	return $columns;
} );

// Handle GTIN column sorting.
add_action( 'pre_get_posts', function( $query ) {
	if ( ! is_admin() || ! $query->is_main_query() ) {
		return;
	}

	if ( 'by_gtin' === $query->get( 'orderby' ) ) {
		$query->set( 'meta_key', '_global_unique_id' );
		$query->set( 'orderby', 'meta_value' );
	}
} );

// Enable search by GTIN.
add_filter( 'woocommerce_product_search_fields', function( $fields ) {
	$fields[] = '_global_unique_id';
	return $fields;
} );

// Add CSS for proper column width.
add_action( 'admin_head', function() {
	$screen = get_current_screen();
	if ( ! $screen || 'edit-product' !== $screen->id ) {
		return;
	}
	?>
	<style>
		.widefat .column-gtin {
			width: 10%;
			min-width: 80px;
		}
	</style>
	<?php
} );