gistfile1.txt

<?php

class My_Module extends Core_ModuleBase
{

	public function subscribeEvents()
	{
	  Backend::$events->addEvent('shop:onExtendCustomerModel', $this, 'extend_customer_model');
	}
	
	public function extend_customer_model($customer, $context)
	{
		$total_orders = 'SELECT COUNT(shop_orders.id) FROM shop_orders WHERE shop_orders.customer_id = shop_customers.id';
		$customer->define_column('total_orders', 'Total orders');
		$customer->calculated_columns['total_orders'] = array(
			'sql' => $total_orders,
			'type' => db_number
		);
			
		$total_spend = 'SELECT IFNULL(SUM(shop_orders.total), 0) FROM shop_orders WHERE shop_orders.customer_id = shop_customers.id';
		$customer->define_column('total_spend', 'Total spend')->currency(true);
		$customer->calculated_columns['total_spend'] = array(
			'sql' => $total_spend,
			'type' => db_float
		);
	}

}