The Problem
Legacy discount logic via Shopify Scripts conflicted with the new Shopify Functions-based checkout after migration, making discount behavior unreliable. At the same time, several types of automatic discounts need to be applied consistently based on customer tags, product tags/SKUs, and destination country, all without relying on manual coupon codes.
The Solution
We implemented a set of dedicated discount Functions inside the pap-checkout-extensions app. A member discount applies 20% off items tagged member20 when the customer is tagged "member" or "gold". A free gift discount grants 100% off one unit of the leather cream when the cart also contains the A4 portfolio. Two investor discount tiers apply, 5% or 10% off based on customer tag (Group 1 or Group 2), excluding specific SKUs. And a shipping discount applies only to shipping methods whose name contains "Express", for customers tagged Level 6 or Level 7 shipping to a configured list of eligible countries.
Why It Mattered
All key automatic discounts now run on a single, modern mechanism that's compatible with the Functions-based checkout. Members, investors, and eligible customers see their discounts applied automatically, with clear labels in checkout and no need for codes. It removes the risk and maintenance overhead of legacy Scripts, keeps complex discount logic stable after the checkout migration, and preserves important commercial rules around loyalty and investor groups.
Technical Details
Built as multiple Shopify Functions configured in the production app. Each discount has its own logic: checking customer tags, SKUs, country codes, and shipping method names, and applies a clearly labeled discount line at checkout. The shipping discount reproduces the behavior of a previous Script using Functions, reading customer tags, and verifying the shipping country is in a defined list before applying the discount only to Express shipping methods.
