medusa

Medusa E-Commerce Skill

Load with: base.md + typescript.md

For building headless e-commerce with Medusa - open-source, Node.js native, fully customizable.

Sources: Medusa Docs | API Reference | GitHub

---

Why Medusa

Feature	Benefit
Open Source	Self-host, no vendor lock-in, MIT license
Node.js Native	TypeScript, familiar stack, easy to customize
Headless	Any frontend (Next.js, Remix, mobile)
Modular	Use only what you need, extend anything
Built-in Admin	Dashboard included, customizable

---

Quick Start

Prerequisites

# Required
node --version  # v20+ LTS
git --version
# PostgreSQL running locally or remote

Create New Project

# Scaffold new Medusa application
npx create-medusa-app@latest my-store

# This creates:
# - Medusa backend
# - PostgreSQL database (auto-configured)
# - Admin dashboard
# - Optional: Next.js storefront

cd my-store
npm run dev

Access Points

URL	Purpose
http://localhost:9000	Backend API
http://localhost:9000/app	Admin dashboard
http://localhost:8000	Storefront (if installed)

Create Admin User

npx medusa user -e admin@example.com -p supersecret

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Project Structure

medusa-store/
├── src/
│   ├── admin/                    # Admin UI customizations
│   │   ├── widgets/              # Dashboard widgets
│   │   └── routes/               # Custom admin pages
│   ├── api/                      # Custom API routes
│   │   ├── store/                # Public storefront APIs
│   │   │   └── custom/
│   │   │       └── route.ts
│   │   └── admin/                # Admin APIs
│   │       └── custom/
│   │           └── route.ts
│   ├── jobs/                     # Scheduled tasks
│   ├── modules/                  # Custom business logic
│   ├── workflows/                # Multi-step processes
│   ├── subscribers/              # Event listeners
│   └── links/                    # Module relationships
├── .medusa/                      # Auto-generated (don't edit)
├── medusa-config.ts              # Configuration
├── package.json
└── tsconfig.json

---

Configuration

medusa-config.ts

import { defineConfig, loadEnv } from "@medusajs/framework/utils";

loadEnv(process.env.NODE_ENV || "development", process.cwd());

export default defineConfig({
  projectConfig: {
    databaseUrl: process.env.DATABASE_URL,
    http: {
      storeCors: process.env.STORE_CORS || "http://localhost:8000",
      adminCors: process.env.ADMIN_CORS || "http://localhost:9000",
      authCors: process.env.AUTH_CORS || "http://localhost:9000",
    },
    redisUrl: process.env.REDIS_URL,
  },
  admin: {
    disable: false,
    backendUrl: process.env.MEDUSA_BACKEND_URL || "http://localhost:9000",
  },
  modules: [
    // Add custom modules here
  ],
});

Environment Variables

# .env
DATABASE_URL=postgresql://user:pass@localhost:5432/medusa
REDIS_URL=redis://localhost:6379

# CORS (comma-separated for multiple origins)
STORE_CORS=http://localhost:8000
ADMIN_CORS=http://localhost:9000

# Backend URL
MEDUSA_BACKEND_URL=http://localhost:9000

# JWT Secrets
JWT_SECRET=your-super-secret-jwt-key
COOKIE_SECRET=your-super-secret-cookie-key

---

Custom API Routes

Store API (Public)

// src/api/store/hello/route.ts
import type { MedusaRequest, MedusaResponse } from "@medusajs/framework/http";

export async function GET(
  req: MedusaRequest,
  res: MedusaResponse
) {
  res.json({
    message: "Hello from custom store API!",
  });
}

// Accessible at: GET /store/hello

Admin API (Protected)

// src/api/admin/analytics/route.ts
import type { MedusaRequest, MedusaResponse } from "@medusajs/framework/http";
import { Modules } from "@medusajs/framework/utils";

export async function GET(
  req: MedusaRequest,
  res: MedusaResponse
) {
  const orderService = req.scope.resolve(Modules.ORDER);

  const orders = await orderService.listOrders({
    created_at: {
      $gte: new Date(Date.now() - 30 * 24 * 60 * 60 * 1000), // Last 30 days
    },
  });

  const totalRevenue = orders.reduce(
    (sum, order) => sum + (order.total || 0),
    0
  );

  res.json({
    orderCount: orders.length,
    totalRevenue,
  });
}

// Accessible at: GET /admin/analytics (requires auth)

Route with Parameters

// src/api/store/products/[id]/reviews/route.ts
import type { MedusaRequest, MedusaResponse } from "@medusajs/framework/http";

export async function GET(
  req: MedusaRequest,
  res: MedusaResponse
) {
  const { id } = req.params;

  // Fetch reviews for product
  const reviews = await getReviewsForProduct(id);

  res.json({ reviews });
}

export async function POST(
  req: MedusaRequest,
  res: MedusaResponse
) {
  const { id } = req.params;
  const { rating, comment, customerId } = req.body;

  const review = await createReview({
    productId: id,
    rating,
    comment,
    customerId,
  });

  res.status(201).json({ review });
}

// Accessible at:
// GET  /store/products/:id/reviews
// POST /store/products/:id/reviews

Middleware

// src/api/middlewares.ts
import { defineMiddlewares } from "@medusajs/framework/http";
import { authenticate } from "@medusajs/framework/http";

export default defineMiddlewares({
  routes: [
    {
      matcher: "/store/protected/*",
      middlewares: [authenticate("customer", ["session", "bearer"])],
    },
    {
      matcher: "/admin/*",
      middlewares: [authenticate("user", ["session", "bearer"])],
    },
  ],
});

---

Modules (Custom Business Logic)

Create Custom Module

// src/modules/reviews/index.ts
import { Module } from "@medusajs/framework/utils";
import ReviewModuleService from "./service";

export const REVIEW_MODULE = "reviewModuleService";

export default Module(REVIEW_MODULE, {
  service: ReviewModuleService,
});

// src/modules/reviews/service.ts
import { MedusaService } from "@medusajs/framework/utils";

class ReviewModuleService extends MedusaService({}) {
  async createReview(data: CreateReviewInput) {
    // Implementation
  }

  async getProductReviews(productId: string) {
    // Implementation
  }

  async getAverageRating(productId: string) {
    // Implementation
  }
}

export default ReviewModuleService;

Register Module

// medusa-config.ts
import { REVIEW_MODULE } from "./src/modules/reviews";

export default defineConfig({
  // ...
  modules: [
    {
      resolve: "./src/modules/reviews",
      options: {},
    },
  ],
});

Use Module in API

// src/api/store/products/[id]/reviews/route.ts
import { REVIEW_MODULE } from "../../../modules/reviews";

export async function GET(req: MedusaRequest, res: MedusaResponse) {
  const { id } = req.params;
  const reviewService = req.scope.resolve(REVIEW_MODULE);

  const reviews = await reviewService.getProductReviews(id);
  const averageRating = await reviewService.getAverageRating(id);

  res.json({ reviews, averageRating });
}

---

Workflows

Define Workflow

// src/workflows/create-order-with-notification/index.ts
import {
  createWorkflow,
  createStep,
  StepResponse,
} from "@medusajs/framework/workflows-sdk";
import { Modules } from "@medusajs/framework/utils";

const createOrderStep = createStep(
  "create-order",
  async (input: CreateOrderInput, { container }) => {
    const orderService = container.resolve(Modules.ORDER);

    const order = await orderService.createOrders(input);

    return new StepResponse(order, order.id);
  },
  // Compensation (rollback) function
  async (orderId, { container }) => {
    const orderService = container.resolve(Modules.ORDER);
    await orderService.deleteOrders([orderId]);
  }
);

const sendNotificationStep = createStep(
  "send-notification",
  async (order: Order, { container }) => {
    const notificationService = container.resolve("notificationService");

    await notificationService.send({
      to: order.email,
      template: "order-confirmation",
      data: { order },
    });

    return new StepResponse({ sent: true });
  }
);

export const createOrderWithNotificationWorkflow = createWorkflow(
  "create-order-with-notification",
  (input: CreateOrderInput) => {
    const order = createOrderStep(input);
    const notification = sendNotificationStep(order);

    return { order, notification };
  }
);

Execute Workflow

// In an API route
import { createOrderWithNotificationWorkflow } from "../../../workflows/create-order-with-notification";

export async function POST(req: MedusaRequest, res: MedusaResponse) {
  const { result } = await createOrderWithNotificationWorkflow(req.scope).run({
    input: req.body,
  });

  res.json(result);
}

---

Subscribers (Event Listeners)

Create Subscriber

// src/subscribers/order-placed.ts
import type { SubscriberArgs, SubscriberConfig } from "@medusajs/framework";

export default async function orderPlacedHandler({
  event,
  container,
}: SubscriberArgs<{ id: string }>) {
  const orderId = event.data.id;

  console.log(`Order placed: ${orderId}`);

  // Send notification, update analytics, etc.
  const notificationService = container.resolve("notificationService");
  await notificationService.sendOrderConfirmation(orderId);
}

export const config: SubscriberConfig = {
  event: "order.placed",
};

Common Events

Event	Trigger
order.placed	New order created
order.updated	Order modified
order.canceled	Order cancelled
order.completed	Order fulfilled
customer.created	New customer registered
product.created	New product added
product.updated	Product modified
`inventory.upda

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