Shopify Basic cart rule
Gate the cart before bad orders reach checkout.
For Shopify stores that need one cart-level rule: vendor-grouped multiples, case exclusions, minimum quantities, or a cart-drawer warning that disables the normal checkout button until the cart is valid.
Theme-level guard only. This is not Shopify Plus checkout validation, not legal/shipping compliance advice, and no store password or customer data is needed for the first pass.
Grouped counts
Validate by vendor or collection.
Use cart line item data to group bottles, parts, or units by a public field before the normal checkout click.
Exclusions
Skip cases, bundles, or tagged products.
The rule can ignore products already sold as a case, bundle, or other excluded category.
Customer message
Show exactly what needs fixing.
Return a clear cart warning naming the group, current count, and next valid quantity.
Test pass
Ship with edge-case checks.
Includes test cases for valid carts, short groups, excluded cases, mixed vendors, and cart drawer updates.
What the $49 job produces
- Paste-ready JavaScript guard for one cart/cart-drawer rule
- Liquid placement notes for common Shopify theme surfaces
- Customer-facing message copy
- CSV test checklist for the owner or developer
Good fits
- Shopify Basic plan, no Shopify Functions access.
- Normal checkout button should be gated until the cart is valid.
- One clear rule with public product/vendor/tag data.
- Owner wants a paste-ready first pass without sharing passwords.
One rule, one snippet