Attach a PDF to the WooCommerce order email

In this tutorial, I’ll show you how to upload a PDF file for each product in WooCommerce and have that file automatically attached to the new order email sent to the customer.

Add a PDF upload field to the product editor

We’ll use add_meta_boxto add a file input in the product edit screen:

<?php
add_action( 'add_meta_boxes', 'addProductPdfUploadBox' );
function addProductPdfUploadBox() {
    add_meta_box(
        'productPdfMeta',
        'Customer PDF File',
        'renderProductPdfMetaBox',
        'product',
        'side'
    );
}

function renderProductPdfMetaBox( $post ) {
    wp_nonce_field( 'saveProductPdfMeta', 'productPdfMetaNonce' );
    $pdfUrl = get_post_meta( $post->ID, '_productPdfUrl', true );

    echo '<input type="file" name="productPdfFile" accept="application/pdf" />';
    if ( $pdfUrl ) {
        echo '<p><a href="' . esc_url( $pdfUrl ) . '" target="_blank">View current PDF</a></p>';
    }
}

Save the uploaded PDF file when saving the product

The uploaded file is saved in the uploadsfolder and its URL is stored in post meta:

<?php
add_action( 'save_post', 'saveProductPdfMeta' );
function saveProductPdfMeta( $postId ) {
    if ( ! isset( $_POST['productPdfMetaNonce'] ) || 
         ! wp_verify_nonce( $_POST['productPdfMetaNonce'], 'saveProductPdfMeta' ) ) {
        return;
    }

    if ( isset( $_FILES['productPdfFile'] ) && $_FILES['productPdfFile']['error'] === UPLOAD_ERR_OK ) {
        require_once ABSPATH . 'wp-admin/includes/file.php';

        $uploadedFile = wp_handle_upload( $_FILES['productPdfFile'], [ 'test_form' => false ] );

        if ( isset( $uploadedFile['url'] ) ) {
            update_post_meta( $postId, '_productPdfUrl', esc_url_raw( $uploadedFile['url'] ) );
        }
    }
}

Attach the PDF to the new order email

We use the woocommerce_email_attachmentsfilter to add the PDF file to the customer new order email:

<?php
add_filter( 'woocommerce_email_attachments', 'attachProductPdfsToEmail', 10, 4 );
function attachProductPdfsToEmail( $attachments, $emailId, $order, $email ) {
    if ( $emailId !== 'customer_processing_order' ) {
        return $attachments;
    }

    foreach ( $order->get_items() as $item ) {
        $productId = $item->get_product_id();
        $pdfUrl    = get_post_meta( $productId, '_productPdfUrl', true );

        if ( $pdfUrl ) {
            $uploadDir = wp_upload_dir();
            $filePath  = $uploadDir['basedir'] . str_replace( $uploadDir['baseurl'], '', $pdfUrl );

            if ( file_exists( $filePath ) ) {
                $attachments[] = $filePath;
            }
        }
    }

    return $attachments;
}

What does this do?

• You can upload a PDF file per product from the admin.
• That PDF will be automatically attached to the customer’s new order email if the product is purchased.
• Files are stored in the uploads folder and are not publicly indexed unless someone has the direct link.