Cart Transform Technology
MOD Bundles uses Shopify's Cart Transform — Shopify's official technology for modifying cart contents and prices. It's installed automatically when you create your first bundle.
Why Cart Transform?
Native Shopify integration — Works with all payment methods and checkout features
Transparent pricing — Customers see accurate totals in cart and checkout
No coupon codes needed — Discount applies automatically
Accurate orders — Correct prices on orders, invoices, and fulfillment
The Discount Flow
Customer completes a bundle — All required selections made
Adds to cart — Bundle items added with metadata identifying them as a bundle
Cart Transform runs — Reads bundle configuration, calculates the discount, distributes it across line items
Discount appears — Each item shows its discounted price in cart and at checkout
Order placed — Discounted prices recorded on the order
How Discounts Distribute Across Items
The total discount is split proportionally across individual line items:
Percentage off: 20% off a $60 bundle = $12 discount distributed across 3 items
Fixed amount off: $10 off distributed proportionally by item price
Fixed price: Difference between item total and bundle price distributed across items
This per-item distribution is why price rounding can occasionally cause a few cents variance.
Bundle Items in Orders
Each product appears as a separate line item with:
Product name, variant, quantity, and discounted price
Bundle metadata (bundle ID, bundle name, position) in line item properties
This means fulfillment works like any regular multi-item order — no special handling needed.
Comparison with Other Discount Methods
MOD Bundles | Discount Codes | Automatic Discounts | |
Customer enters code | No | Yes | No |
Works with bundles | Yes (native) | Partially | Partially |
Stacks with other discounts | Depends | Often no | Depends |
Troubleshooting
Discount not showing — Ensure bundle is complete (all items selected); verify items were added via the bundle interface
Wrong discount amount — Check bundle settings; verify product prices in Shopify; see Price Rounding
Discount appears then disappears — Adding/removing cart items can affect bundles; try clearing cart and re-adding
See Discount Not Applying for more help.