Help with Checkout Extension: Restricting Manual Discount to One Free Item

Shopify Apps
1

Hi everyone,

I’m building a Shopify checkout extension using the Product Discount API function and need some guidance.

Current Issue:

  • When a manual discount is applied at checkout to a product with quantity X, all units are becoming free.

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  • I need to ensure that only one unit is free, while the remaining units are charged at the normal price.

Example Scenario:

  • A customer buys 5 units of a product and applies a 100% discount at checkout.
  • Expected behavior: Only 1 unit should be free, and the remaining 4 units should be charged at full price.
  • Current behavior: All 5 units are becoming free, which is incorrect.

I’m trying to implement this restriction within the checkout extension using the Product Discount API function. Has anyone faced a similar issue or found a workaround? Any help would be greatly appreciated!

Thanks in advance!