Shopify Cart Transform API Template (July 2025)

A practical Shopify Node template for API development (July 2025) that demonstrates dynamic bundle creation using Cart Transform Functions and metafield-driven configuration.

This project is designed to help developers learn how to:

• map a target product to a bundle product from an admin UI
• store transformation rules in Shopify metafields
• automatically expand cart line items at runtime via Shopify Functions

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Key Features

• Dynamic bundle creation at cart level (no fixed bundle products required)
• Metafield-driven transform rules for flexible configuration
• Admin product selection flow using Shopify App Bridge
• Automatic cart transform creation when missing
• Backend endpoints for reading and writing transform config
• Shopify Function-based line expansion for performant checkout logic

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Tech Stack

• Frontend: React, Shopify Polaris, Shopify App Bridge
• Backend: Node.js, Express
• Shopify APIs: GraphQL Admin API, Metafields API, Cart Transform API
• Runtime Logic: Shopify Functions (cartTransformRun)

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Working Example

Scenario

You select:

• Target product variant: Product A
• Bundle product variant: Product B

The configuration is saved in metafield:

• Namespace: app
• Key: function-configs
• Type: json

Input Cart

• Product A (qty: 1)

Output Cart (After Transform)

• Product A (qty: 1)
• Product B (qty: 1)

Example Transform Payload

{
  "transform": [
    { "id": "target_variant_id", "title": "Target Product" },
    { "id": "bundle_variant_id", "title": "Bundle Product" }
  ]
}

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Flow

1. Product Selection (Frontend)

   • Admin picks target and bundle products from resource picker.

2. Save Config (Backend + Metafield)

   • POST /api/cart/create-transform writes configuration using metafieldsSet.

3. Resolve Transform (Backend)

   • GET /api/cart/transformations fetches existing transform and creates one if absent.

4. Cart Runtime Execution (Shopify Function)

   • cartTransformRun(input) reads cart lines and metafield config.
   • If a target match is found, it expands the line with the mapped bundle variant.

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Project Structure

/frontend
  ├── pages/HomePage.jsx
  ├── components/
/backend
  ├── index.js
  ├── shopify.js
  ├── product-creator.js
/functions
  ├── cartTransformRun.js
/graphql
  ├── CartTransformRunInput.query.graphql

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License

This project is open source under the MIT License.

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Author

StackWise Dev
Created for educational purpose to demonstrate Shopify Cart Transform API patterns with a Node template.