Magento API gives Access Denied when trying to add a coupon

Question

I am using the SOAP API for Magento (v1.5.1.0) and have managed to get the entire process of creating a cart, adding user, adding billing/shipping addresses, payment methods, etc. working, however I cannot get Coupons to work.

The code I'm using is as follows:

if ($couponCode != '') {
    try {
        $result = $this->magentoservice->shoppingCartCouponAdd($sessionId, $cartId, $couponCode);                
    } catch (Exception $err) {
        return $this->returnError($err->getMessage());
    }
}

I've tried with both a guest user and a registered user and I keep getting the same exception thrown - "Access denied.". As far as I can see from the limited documentation and forums posts this isn't even an expected error.

$sessionId and $cartId are definately valid. The $couponCode if entered directly on the magento frontend works.

Can anyone advise me how I might be able to solve this?

Answer 1

Make sure that the API user has access to the coupon code resource (set under the API role)

Answer 2

It seems that ACL for coupons is not defined. Please merge the following snippet into ../Mage/Checkout/etc/api.xml. It should make proper ACL item available in the the admin panel.

<config>
    <api>
        <resources>
            <cart_coupon translate="title" module="checkout">
                <acl>cart/coupon</acl>
                <methods>
                    <add translate="title" module="checkout">
                        <title>Add coupon code for shopping cart</title>
                        <method>add</method>
                        <acl>cart/coupon/add</acl>
                    </add>
                </methods>
            </cart_coupon>
        </resources>
        <acl>
            <resources>
                <cart translate="title" module="checkout">
                    <title>Shopping Cart</title>
                    <coupon>
                        <title>Shopping cart ability to set coupon code</title>
                        <add>
                            <title>Add coupon code for shopping cart</title>
                        </add>
                    </coupon>
                </cart>
            </resources>
        </acl>
    </api>
</config>