Magento Coupons limit per use o per customer not working

Question

In the screenshot you can see my options.

I have created a coupon to have the free first shippings.

What i need is to have one unique code (Example: FREEFIRSTSHIPPING) that can be used only one time, but that every logged customers can use this same code one time.

The code works well, setting my Uses per Coupon value to 0, but i have noticed that i can use this code unlimited times, and this is wrong.

Is it a Magento 1.9 bug? Or am i doing something wrong?

PS: I have no coupons related extensions installed.

Answer 1

It's a known magento bug. Magento does not track coupons with empty discount (as in your case)

Correct settings are:

• Use per coupon = 0 or empty,

• Use per client = 1,

And modify the code in the Mage_SalesRule_Model_Observer (copy to local of course) from

    // use each rule (and apply to customer, if applicable)
    if ($order->getDiscountAmount() != 0) {

to, say

    if (true) {

Edit: You can just copy the file from

app\code\ **core** \Mage\SalesRule\Model\Observer.php 

to

app\code\ **local** \Mage\SalesRule\Model\Observer.php

and make all changes in the local version.

Answer 2

I came across this today and was able to solve it thanks to @Amaty's comment.

Here are some more details:

The core module Mage_SalesRule registers a global observer to run after each sales order is placed.

This observer increments the times_used counter on coupon codes, this is used for enforcing limits.

The code to increment times_used is inside the following if statement:

if ($order->getDiscountAmount() != 0) {
    // snip
}

This means that if the order discount_amount is 0 no processing happens.

Source: https://github.com/OpenMage/magento-mirror/blob/magento-1.9/app/code/core/Mage/SalesRule/Model/Observer.php#L72-L133

Free Shipping coupons

Typically a Sales Rule set up to allow free shipping with no other discount will be set up as below:

One or many coupons are then created, a typical use case is multiple coupons valid for a single use per coupon.

Because of the logic around incrementing times_used when these coupons are used, if no other discounts apply, then the coupon will not be marked as used.

The Coupon Codes will however provide the correct "Free Shipping discount" and continue to work for later transactions. This means the merchant is discounting more than they intended with the free shipping coupon.

A Fix

I elected not to overwrite the existing core module's observer but rather create a new global observer of my own and use identical logic except for the following:

if ($order->getDiscountAmount() == 0) {
    // snip
}

This means the core observer will run and process all coupon_codes for orders with a DiscountAmount. The observer that I've put together will run for all others - this is so I can leave core untouched without double counting coupon usage.

I have published this as a module here: https://github.com/etailer/Etailer_CouponUsed/

I also wrote a Magento shell script that iterates through all orders with no discount_amount and a coupon_code present. It then increments their times_used. This is optional but I found it very useful to quickly void all the used coupons. It can also be extracted and used standalone if you've fixed the core issue some other way.