Case study · 2026
Exact Online → Shopify Pre-Order Automation
Pre-order inventory was being typed into Shopify by hand even though Exact already knew what stock was coming.
- Shopify
- Exact Online API
- Node.js
- OAuth 2.0
- Discipline
- ERP integration · Pre-order automation · Inventory logic
- Year
- 2026
- Engagement
- Fixed scope
- Status
- Live
01Context
- Replace manual Timesact pre-order quantities with Exact inventory.
- Enable and disable Shopify pre-orders automatically by SKU.
- Cap orders according to available incoming stock.
Weldaad previously used Timesact to manage Shopify pre-orders. Expected inventory had to be entered manually and then adjusted again when incoming products physically arrived.
Exact Online already contained warehouse and incoming-stock information, making the duplicate manual workflow unnecessary.
HeapByte built a custom Exact-to-Shopify pre-order system so Shopify availability could respond automatically to actual inventory data.
02What was in the way
- 01
Multiple inventory states
On-hand, available, committed, expected, and warehouse-specific stock all affect whether something is genuinely purchasable.
- 02
Variant-level control
Pre-order decisions had to operate at SKU level rather than merely at Shopify product level.
- 03
Large inventory dataset
The initial Exact response was paginated, and failing to handle pagination correctly meant large portions of the catalog could silently disappear from calculations.
03Architecture
What we built, and what we deliberately left alone.
- 01
Exact OAuth integration
The app securely connects to Exact Online and maintains authenticated API access.
- 02
Shopify metafield state
Pre-order enabled status and pre-order cap are stored against Shopify and controlled by the application.
- 03
Scheduled reconciliation
Inventory is synchronized periodically with additional update paths when relevant stock changes.
Delivery
- Exact authentication
- Inventory API integration
- Pre-order rules engine
- Theme integration
- QA & launch
04Outcome
- Inventory scale
- 1,500+ SKUs
- Auto refresh
- 30 minutes
- Manual workflow
- Removed
- Third-party dependency
- Replaced
Exact pagination expanded synchronization beyond the first 500 records
Scheduled preorder reconciliation
Expected-stock quantities no longer require routine Timesact maintenance
Custom logic took over core preorder behavior
“This man can do anything!”
05Engineering notes
- Inventory state machine
- Products transition between normal sale, pre-order, and sold-out based on calculated stock conditions.
- Warehouse filtering
- Only the designated Exact warehouse contributes inventory to the relevant Shopify preorder calculation.
- Committed inventory
- Committed quantities were incorporated so products with zero truly available stock could still be treated correctly.
- Theme integration
- Collection cards, product pages, button labels, badges, and cart behavior all consume the same preorder state.
What we took from it
- 01ERP inventory terminology must be understood before implementing storefront behavior.
- 02API pagination failures can masquerade as business-logic bugs.
- 03Pre-order logic belongs at SKU level when products have variants.
- 04Existing inventory middleware must be treated as part of the architecture, not ignored.
Disciplines applied
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