Fix: Error selecting applicable discounts

[se09deluca]

The discount selection currently takes all the discounts with and without coupon code because of this conditional query

->when($cart?->coupon_code,
                fn ($query, $value) => $query->where('coupon', '=', $value)->orWhere(fn ($query) => $query->whereNull('coupon')->orWhere('coupon', '')),
                fn ($query, $value) => $query->whereNull('coupon')->orWhere('coupon', '')
            )

when the $cart?->coupon_code is true, it executes the first closure in which it selects the discounts having the correct coupon but also the discounts with null coupon code or empty strings. Only the second clousure (executed when $cart?->coupon_code is false) should selects the discount with null coupons or empty.

This issue currently make the query selects all the discounts that has no coupon_code (even the expired ones, because of the OR clause)
Below a simplified result of the ->toSql() of the query.

select *
from `lunar_discounts`
where `starts_at` is not null and `starts_at` <= now() and (`ends_at` is null or `ends_at` > now())
          and (uses < max_uses or `max_uses` is null)
          and `coupon` = 'EXAMPLE_CODE' or (`coupon` is null or `coupon` = '')
order by `priority` desc, `id` asc

The PR essentially changes the positive closure. By making use of a where condition with a closure, the query builder creates a logical group around the WHERE conditions and the resulting SQL query will have the affected conditions placed in parentheses, as the simplified example below:

select *
from `lunar_discounts`
where `starts_at` is not null and `starts_at` <= now() and (`ends_at` is null or `ends_at` > now())
          and (uses < max_uses or `max_uses` is null)
          and (`coupon` = 'EXAMPLE_CODE' or `coupon` is null or `coupon` = '')
order by `priority` desc, `id` asc

PS: the provided example are simplified because for readability purpose i removed the subqueries relative to channels, customer groups and discount's purchasables.

[vercel]

The latest updates on your projects. Learn more about Vercel for Git ↗︎

Name	Status	Preview	Comments	Updated (UTC)
lunar-docs	✅ Ready (Inspect)	Visit Preview	💬 Add feedback	Jan 11, 2024 9:47am