The basic goal of what it'm trying to achieve is detecting if a user has signed up as a Member on the site, and if not, require them to purchase a Membership product the first time they check out.
The general logic and behavior is:
- Inspect the customer to see if they have no previous orders, and/or have (or do not have) a specific tag (exact mechanism is TBD, but is likely to be one of these two things).
- If that inspection shows they are not a Member, show an error, prevent checkout, and if they don't already have a Membership product in their cart, display an Add button that will add the required Membership product to the cart.
I can easily do most of this with a Checkout Validation Function using buyerIdentity.customer.numberOfOrders. That can display the error message and prevent checkout. Great.
I can also use a simple Checkout UI Extension to show the Add button for the Membership product if it is not in the cart already. Great, almost.
What i cannot figure out how to do is link triggering the display of the Add button to the outcome of the Validation. I ONLY want to display the Add button if the customer is not a member (per data on the customer) and there is no Membership in the cart yet.
There doesn't seem to be a way to write back to the Cart during the Validation, and the customer data i want to inspect is not available to the Checkout UI Extension.
I feel like i may be missing something obvious here, but i can't figure out what. Is this something that should be possible? It seems like a very common use case, and in fact is mentioned in the "Example Use Cases" section here:
https://shopify.dev/docs/api/functions/reference/cart-checkout-validation
There is nothing showing how that might be done of course, so not a very useful list.
