medusa-starter/src/modules

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 = "helloModuleService"

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: {
    [HELLO_MODULE]: {
      resolve: "./modules/hello",
    },
  },
})

Its key (helloModuleService or HELLO_MODULE) is the name of the module’s main service. It will be registered in the Medusa container with that name.

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(),
  })
}