Export selected data about the currently shown WooCommerce orders to a CSV file

_export-orders.php

<?php
/**
 * Function to export the orders list to a CSV download (not stored anywhere)
 * CSV construction based on https://gist.github.com/vrushank-snippets/4274500
 * Dev notes:
 * - This file is designed to be called via AJAX, with that function providing the order IDs.
 * - To use this without AJAX you would just need to define $order_ids = wp_list_pluck($wp_query->posts, 'ID') instead,
 *   and define $filename as something appropriate here.
 */
function doublee_export_orders() {
	$order_ids = json_decode($_POST['order_ids']);
	$results = array();

	// Check security nonce from AJAX request
	if (!check_ajax_referer('exporter-nonce', 'security', false)) {
		wp_send_json_error('Invalid security token sent.');
		wp_die();
	}

	if(is_admin() && !empty($order_ids)) {

		// For each order:
		foreach ($order_ids as $order_id) {
			$order = wc_get_order($order_id);

			// Get data we want to export
			$user_id              = $order->get_user_id();
			$user_name            = get_user_meta($user_id, 'first_name', true).' '.get_user_meta( $user_id, 'last_name', true );
			$products             = doublee_get_order_products($order_id);
			$products_ordered     = implode(', ', $products); // Comma-separated list of product names
			$order_date           = $order->get_date_created()->getTimestamp();
			$order_date_formatted = date( 'd/m/Y' );
			$status               = $order->get_status();

			// Put it all into an array
			$order_data = array(
				'Order ID'         => $order_id,
				'Customer name'    => $user_name,
				'Product(s)' 	   => $products_ordered,
				'Order date'       => $order_date_formatted,
				'Status'           => $status
			);

			// Add it to the $results array
			$results[$order_id] = $order_data;
		}

		// Temp name for the CSV file
		$filename = 'temp.csv';

		// Set headers for the CSV file download
		header( "Cache-Control: must-revalidate, post-check=0, pre-check=0" );
		header( 'Content-Description: File Transfer' );
		header( "Content-type: text/csv" );
		header( "Content-Disposition: attachment; filename={$filename}" );
		header( "Expires: 0" );
		header( "Pragma: public" );

		// Open the file
		$fh = fopen( 'php://output', 'w' );

		// When we first begin, the file doesn't have the header row
		$headerDisplayed = false;

		// Loop through the data array and add rows to the file
		foreach ($results as $data) {
			// Add a header row if it hasn't been added yet
			if (!$headerDisplayed) {
				// Use the keys from $data as the titles
				fputcsv($fh, array_keys($data));
				$headerDisplayed = true;
			}

			// Put the data into the stream
			fputcsv($fh, $data);
		}

		// Close the file
		fclose($fh);
	}

	exit();
}
add_action('wp_ajax_doublee_export_orders', 'doublee_export_orders');

add-button.php

<?php
/**
 * Add the export button to the Orders screen.
 * Note: Use CSS to adjust the appearance and positioning of the button.
 *
 * @param $which 'top' or 'bottom'
 */
function doublee_add_order_export_button_in_admin($which) {
	$screen = get_current_screen();
	if(is_admin() && $screen->base == 'edit' && $screen->post_type == 'shop_order' && $which == 'top') {
		echo '<div class="alignleft export">';
			echo '<button id="export-orders-button" class="button">Export these orders</button>';
		echo '</div>';
	}
}
add_action('manage_posts_extra_tablenav', 'doublee_add_order_export_button_in_admin');

ajaxable.php

<?php
/**
 * The export function is called via AJAX for a smooth admin experience, but has no awareness of what page it's on and hence the current query.
 * This function makes the current query's order IDs available to the JavaScript file so the AJAX function can send which order IDs it wants to export.
 * Here we also set a limit on how many can be exported at once, to prevent timeouts,
 * and let the script know what page we're on for file naming purposes ($wp_query accounts for the number of items per page set in Screen Options).
 * The other localised variables are here too because having wp_localize_script run more than once causes only the last one to be used.
 */
function doublee_make_current_order_ids_ajaxable() {
	if(current_user_can('manage_woocommerce')) {
		global $wp_query;
		$query_limit = 50;
		$all_ids = wp_list_pluck($wp_query->posts, 'ID');
		$limit_exceeded = false;
		if(count($all_ids) > $query_limit) {
			$limit_exceeded = true;
		}
		$page = '1';
		if($wp_query->query['paged'] > 1) {
			$page = $wp_query->query['paged'];
		}
		wp_localize_script('order-export', 'doubleedesign', array(
			'ajaxurl'       => admin_url('admin-ajax.php'),
			'security'      => wp_create_nonce('exporter-nonce'),
			'order_ids'     => array_slice($all_ids, '0', 50),
			'export_limit'  => $query_limit,
			'export_limit_exceeded' => $limit_exceeded,
			'result_page'   => $page
		));
	}
}
add_action('wp', 'doublee_make_current_order_ids_ajaxable', 50);

run-export-via-ajax.js

jQuery(document).ready(function($) {

	$('#export-orders-button').on('click', function(event) {
		event.preventDefault();
		var default_label = $(this).text();

		// Check that there's actually orders to export before proceeding.
		if(doubleedesign.order_ids.length === 0) {
			alert('Please select some orders to export');
			return;
		}

		// Show message if limit is exceeded (limit exists to prevent timeouts)
		if(doubleedesign.export_limit_exceeded == true) {
			alert('Please select a maximum of 50 orders to export at a time');
			return;
		}
		
		// Set filename
		var today = new Date();
		var filename = 'Orders-' + today.toISOString().substring(0, 10) + '--Page-' + doubleedesign.result_page + '.csv';

		// Add loading state
		$(this).addClass('loading');
		$(this).text('Exporting orders');

		// Ajax function to run the export
		$.ajax({
			method: 'POST',
			dataType: 'text',
			url: doubleedesign.ajaxurl,
			data: {
				action: 'doublee_export_orders',
				security: doubleedesign.security,
				order_ids:  JSON.stringify(doubleedesign.order_ids)
			},
			success: function (response) {

				// Make CSV in the response downloadable by creating a blob
				var download_link = document.createElement("a");
				var fileData = ['\ufeff'+response];
				var blobObject = new Blob(fileData,{
					type: "text/csv;charset=utf-8;"
				});

				// Actually download the CSV by temporarily creating a link to it and simulating a click
				download_link.href = URL.createObjectURL(blobObject);
				download_link.download = filename;
				document.body.appendChild(download_link);
				download_link.click();
				document.body.removeChild(download_link);

				// Remove the export button's loading state
				$('#export-orders-button').removeClass('loading').text(default_label);
			},
			error: function(response) {
				console.log(response);
				$('#export-orders-button').removeClass('loading').addClass('error').text('Error exporting');
			},
		})
	})
});

utility-get-order-products.php

<?php
/**
 * Utility function to get the product names (not every order item - disregard product addons) in an order
 * as Product ID => Name pairs
 * @param $order_id
 *
 * @return array
 */
function doublee_get_order_products($order_id) {
	$order = wc_get_order($order_id);
	$items = $order->get_items();

	// Each product format (which is a Product Addon) shows up as an order item.
	// Get just the products by looping through and getting the product IDs
	$product_ids = array();
	foreach($items as $item) {
		array_push($product_ids, $item->get_product_id());
	}

	// Only include each product once, not for every addon
	$product_ids = array_unique($product_ids);

	// Create an array of product ID => name pairs
	$product_list = array();
	foreach($product_ids as $product_id) {
		$product = wc_get_product($product_id);
		if($product) {
			$product_list[$product_id] = $product->get_name();
		}
	}

	// Return that array
	return $product_list;
}