WooCommerce: Automatically complete virtual orders

woocommerce-auto-complete-virtual-orders.php

<?php

add_filter( 'woocommerce_payment_complete_order_status', 'wmg_auto_complete_virtual_orders', 10, 3 );

/**
 * Automatically complete orders with only virtual products
 *
 * @param  string   $payment_complete_status Order status used after an order payment is received
 * @param  int      $order_id                ID of the order being processed
 * @param  WC_Order $order                   Order object being processed
 * @return string   $payment_complete_status Updated order status
 */
function wmg_auto_complete_virtual_orders( $payment_complete_status, $order_id, $order ) {
  $current_status = $order->get_status();
  // We only want to update the status to 'completed' if it's coming from one of the following statuses: 
  $allowed_current_statuses = array( 'on-hold', 'pending', 'failed' );

  if ( 'processing' === $payment_complete_status && in_array( $current_status, $allowed_current_statuses ) ) {

    $order_items = $order->get_items();

    // Create an array of products in the order
    $order_products = array_filter( array_map( function( $item ) {
      // Get associated product for each line item
      return $item->get_product();
    }, $order_items ), function( $product ) {
      // Remove non-products
      return !! $product;
    } );

    if ( count( $order_products ) > 0 ) {
      // Check if each product is 'virtual'
      $is_virtual_order = array_reduce( $order_products, function( $virtual_order_so_far, $product ) {
        return $virtual_order_so_far && $product->is_virtual();
      }, true );

      if ( $is_virtual_order ) {
        $payment_complete_status = 'completed';
      }
    }

  }

  return $payment_complete_status;
}

@Croolw @gbozzetti @nmbgeek

The line:
if ( count( $order_products > 0 ) ) {

Needs to be changed to:

if ( count( $order_products ) > 0 ) {

Note the correct placement of the close bracket on the count() function - this fixes the error you are all encountering