In this episode, we dive into how to keep your shopping cart's product quantities in sync with the actual product stock available. The goal is to make sure that if another user or purchase causes quantities to change (for example, by buying the last item), our cart reflects those changes smoothly for our users.
We're building a method in our cart model called syncAvailableQuantities
. The idea is to loop through the items in the cart, compare their quantities to the current stock in the database, and update (or reduce) them if needed. If a product's stock drops to zero (or goes below the requested quantity), we'll adjust or even remove it from the cart. We pay close attention to the array structure needed for Laravel's sync()
method on relationships, mapping variation IDs to the correct quantities, and making sure this mapping is clean and verbose so it's easy to follow.
There's also a practical walkthrough of testing this in the database--updating stocks, checking how that's reflected in the cart after syncing, and making sure our cart's data stays accurate. When a product's quantity in the cart goes to zero, we use Laravel collection methods to reject it from our cart array. Then, by using the sync()
method, Eloquent handles removing or updating the cart items as needed.
To make the UX seamless, we also clear the cart's instance cache so users instantly see up-to-date quantities without any weird refresh issues. Finally, we ensure this logic is plugged into both the cart and checkout controllers, so cart changes show up no matter where the user is.
So basically, if product stock changes out from under your user, the cart gets automatically updated to reflect the new max they can buy—right before they check out. Handy, right?