programmatically check if coupon code is correct

Question

I need to check to see if a coupon code is correct in an ajax controller, how is this done?

I get the code like this:

$param['code'];

Answer 1

Try

couponCode = $param['code'] 
$oCoupon = Mage::getModel('salesrule/coupon')->load($couponCode, 'code');
$oRule = Mage::getModel('salesrule/rule')->load($oCoupon->getRuleId());

Then try to apply it to your order see Check if coupon is valid for a quote