Custom Module

A module is a package of reusable functionalities. It can be integrated into your Medusa application without affecting the overall system.

To create a module:

1. Create a Service

A module must define a service. A service is a TypeScript or JavaScript class holding methods related to a business logic or commerce functionality.

For example, create the file src/modules/hello/service.ts with the following content:

export default class HelloModuleService {
  getMessage() {
    return "Hello, world!"
  }
}

2. Export Module Definition

A module must have an index.ts file in its root directory that exports its definition. The definition specifies the main service of the module.

For example, create the file src/modules/hello/index.ts with the following content:

import HelloModuleService from "./service"
import { Module } from "@medusajs/framework/utils"

export const HELLO_MODULE = "hello"

export default Module(HELLO_MODULE, {
  service: HelloModuleService,
})

3. Add Module to Configurations

The last step is to add the module in Medusa’s configurations.

In medusa-config.js, add the module to the modules object:

import { HELLO_MODULE } from "./src/modules/hello"

module.exports = defineConfig({
  // ...
  modules: [
    {
      resolve: "./modules/hello",
    }
  ]
})

Use Module

You can resolve the main service of the module in other resources, such as an API route:

import { MedusaRequest, MedusaResponse } from "@medusajs/framework"
import HelloModuleService from "../../../modules/hello/service"
import { HELLO_MODULE } from "../../../modules/hello"

export async function GET(
  req: MedusaRequest,
  res: MedusaResponse
): Promise<void> {
  const helloModuleService: HelloModuleService = req.scope.resolve(
    HELLO_MODULE
  )

  res.json({
    message: helloModuleService.getMessage(),
  })
}