Magento: Fatal error: Call to a member function getModelInstance() on a non-object in app\Mage.php on line 432

Question

I want to call a PHP file using ajax where in that PHP i will place order by the ajax call. But it throws error while i am using app/Mage.php from that file

Answer 1

I personally had solved it by using

$customer = new Mage_Customer_Model_Customer();

instead of using

$customer = Mage::getModel('customer/customer');