Two made-to-order products can each appear available when checked alone and still conflict when a customer adds both to one cart. The store needs the combined material requirement checked before accepting an order.
Illustrative scenario: The quantities are a demonstration, not a real merchant's orders or conversion results.
Calculate the whole cart
There are 5 meters of fabric available to use. One canvas bag needs 3 meters and one apron needs 3 meters.
| Cart selection | Fabric required | Result against 5 m |
|---|---|---|
| One canvas bag | 3 m | Within the material limit |
| One apron | 3 m | Within the material limit |
| One of each | 6 m | Exceeds the limit by 1 m |
The store must not treat the two individual availability checks as separate fabric pools. The mixed cart requests 6 meters from one 5-meter pool.
Configure the shared requirement
- In Raw Materials, use one active fabric material with the correct current Available to use quantity.
- Bind the bag and apron Shopify variants to that same material under Product Usage, each with 3 meters as Consumption Per Unit. Check for other required materials as well.
- In Inventory rules, confirm the inventory mode includes raw materials and Cart & checkout validation is Active. Its enable/disable control takes effect immediately and is separate from other page settings.
- Test three carts: one bag, one apron, and one of each. Complete a checkout-stage test for the combined cart. The optional storefront cart quantity control is a separate theme feature; its status alone does not confirm checkout validation.
When different cart variants together exceed a shared material, Soply can show a Cart Item Conflict message. Under Inventory rules → Customize Error Messages, the store can make this message more useful, for example: These items share limited material stock: {conflicting_variants}. Please reduce your cart quantity. Test the rendered message in the store's active languages. Use only the supported placeholder names and stay within the 500-character limit.
Verify the rule's scope
The example assumes neither product is configured to allow selling when raw material is insufficient. That option deliberately changes shortage behavior. Check recent reservations and material snapshots if the available quantity differs from five meters. The storefront cart may help customers adjust quantities, but the checkout validation status and actual checkout test are the decisive checks for this scenario.
See Shared fabric across variants, Material availability calculations, Cart and checkout validation, and Customize validation messages.
Real results depend on your products, stock, markets, store settings, and test conditions. Verify the setup in your own store.
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