medusa-store/www/apps/docs/content/development/endpoints/example-logged-in-user.mdx

---
description: 'In this document, you’ll see an example of how you can use middlewares and endpoints to register the logged-in user in the dependency container of your commerce application.'
addHowToData: true
---

import Troubleshooting from '@site/src/components/Troubleshooting'
import ServiceLifetimeSection from '../../troubleshooting/awilix-resolution-error/_service-lifetime.md'
import CustomRegistrationSection from '../../troubleshooting/awilix-resolution-error/_custom-registration.md'

# Example: Access Logged-In User

In this document, you’ll see an example of how you can use middlewares and endpoints to register the logged-in user in the dependency container of your commerce application. You can then access the logged-in user in other resources, such as services.

This guide showcases how to register the logged-in admin user, but you can apply the same steps if you want to register the current customer.

This documentation does not explain the basics of [middlewares](./add-middleware.mdx) and [endpoints](./create.mdx). You can refer to their respective guides for more details about each.

## Step 1: Create the Middleware

Create the file `src/api/middlewares/logged-in-user.ts` with the following content:

```ts title=src/api/middlewares/logged-in-user.ts
import { User, UserService } from "@medusajs/medusa"

export async function registerLoggedInUser(req, res, next) {
  let loggedInUser: User | null = null

  if (req.user && req.user.userId) {
    const userService = 
      req.scope.resolve("userService") as UserService
    loggedInUser = await userService.retrieve(req.user.userId)
  }

  req.scope.register({
    loggedInUser: {
      resolve: () => loggedInUser,
     },
   })
  
  next()
}
```

This retrieves the ID of the current user to retrieve an instance of it, then registers it in the scope under the name `loggedInUser`.

---

## Step 2: Apply Middleware on Endpoint

If you don't have the `cors` package installed, make sure to install it first:

```bash npm2yarn
npm install cors
```

Then, create the file `src/api/routes/create-product.ts` with the following content:

```ts title=src/api/routes/create-product.ts
import cors from "cors"
import { Router } from "express"
import { 
  registerLoggedInUser,
} from "../middlewares/logged-in-user"
import 
  authenticate 
from "@medusajs/medusa/dist/api/middlewares/authenticate"

const router = Router()

export default function (adminCorsOptions) {
  // This router will be applied before the core routes. 
  // Therefore, the middleware will be executed
  // before the create product handler is hit
  router.use(
    "/admin/products", 
    cors(adminCorsOptions), 
    authenticate(),
    registerLoggedInUser
  )
  return router
}
```

In the example above, the middleware is applied on the `/admin/products` core endpoint. However, you can apply it on any other endpoint. You can also apply it to custom endpoints.

For endpoints that require Cross-Origin Resource Origin (CORS) options, such as core endpoints, you must pass the CORS options to the middleware as well since it will be executed before the underlying endpoint.

:::tip

In the above code snippet, the `authenticate` middleware imported from `@medusajs/medusa` is used to ensure that the user is logged in first. If you're implementing this for middleware to register the logged-in customer, make sure to use the [customer's authenticate middleware](./create.mdx#protect-store-routes).

:::

---

## Step 3: Register Endpoint in the API

Create the file `src/api/index.ts` with the following content:

```ts title=src/api/index.ts
import configLoader from "@medusajs/medusa/dist/loaders/config"
import createProductRouter from "./routes/create-product"

export default function (rootDirectory: string) {
  const config = configLoader(rootDirectory)

  const adminCors = {
    origin: config.projectConfig.admin_cors.split(","),
    credentials: true,
  }

  const productRouters = [
    createProductRouter(adminCors),
  ]

  return [...productRouters]
}
```

This exports an array of endpoints, one of them being the product endpoint that you applied the middleware on in the second step. You can export more endpoints as well.

---

## Step 4: Use in a Service

You can now access the logged-in user in a service. For example, to access it in a custom service:

<!-- eslint-disable prefer-rest-params -->

```ts
import { Lifetime } from "awilix"
import { 
  TransactionBaseService, 
  User,
} from "@medusajs/medusa"

class HelloService extends TransactionBaseService {

  protected readonly loggedInUser_: User | null

  constructor(container, options) {
    super(...arguments)

    try {
      this.loggedInUser_ = container.loggedInUser
    } catch (e) {
      // avoid errors when backend first runs
    }
  }

  // ...
}

export default HelloService
```

If you're accessing it in an extended core service, it’s important to change the lifetime of the service to `Lifetime.SCOPED`. For example:

<!-- eslint-disable prefer-rest-params -->

```ts
import { Lifetime } from "awilix"
import { 
  ProductService as MedusaProductService, 
  User, 
} from "@medusajs/medusa"

// extend core product service
class ProductService extends MedusaProductService {
  // The default life time for a core service is SINGLETON
  static LIFE_TIME = Lifetime.SCOPED

  protected readonly loggedInUser_: User | null

  constructor(container, options) {
    super(...arguments)

    this.loggedInUser_ = container.loggedInUser
  }
}

export default ProductService
```

You can learn more about the importance of changing the service lifetime in the [Middlewares documentation](./add-middleware.mdx#note-about-services-lifetime).

---

## Step 5: Test it Out

To test out your implementation, run the following command in the root directory of the Medusa backend to transpile your changes:

```bash npm2yarn
npm run build
```

Then, run your backend with the following command:

```bash npm2yarn
npx medusa develop
```

If you try accessing the endpoints you added the middleware to, you should see your implementation working as expected.

---

## Troubleshooting

<Troubleshooting 
  sections={[
    {
      title: 'AwilixResolutionError: Could Not Resolve X',
      content: <ServiceLifetimeSection />
    },
    {
      title: 'AwilixResolutionError: Could Not Resolve X (Custom Registration)',
      content: <CustomRegistrationSection />
    }
  ]}
/>