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118 lines
3.0 KiB
Markdown
118 lines
3.0 KiB
Markdown
# Create a Service
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In this document, you’ll learn how you can create a [Service](./overview.md) and use it across your Medusa server just like any of the core services.
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## Implementation
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To create a service, create a TypeScript or JavaScript file in `src/services` to hold the service. The name of the file should be the registration name of the service without `Service` as it will be appended to it by default.
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For example, if you want to create a service `helloService`, create the file `hello.ts` in `src/services` with the following content:
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```ts title=/src/services/hello.ts
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import { TransactionBaseService } from "@medusajs/medusa"
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import { EntityManager } from "typeorm"
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class HelloService extends TransactionBaseService {
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protected manager_: EntityManager
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protected transactionManager_: EntityManager
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getMessage() {
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return `Welcome to My Store!`
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}
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}
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export default HelloService
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```
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---
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## Service Constructor
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As the service extends the `TransactionBaseService` class, all services in Medusa’s core, as well as all your custom services, will be available in your service’s constructor using dependency injection.
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So, if you want your service to use another service, simply add it as part of your constructor’s dependencies and set it to a field inside your service’s class:
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```ts
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class HelloService extends TransactionBaseService {
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private productService: ProductService
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constructor(container) {
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super(container)
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this.productService = container.productService
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}
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// ...
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}
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```
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Then, you can use that service anywhere in your custom service:
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```ts
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class HelloService extends TransactionBaseService {
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// ...
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async getProductCount() {
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return await this.productService.count()
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}
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}
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```
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---
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## Use a Service
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In this section, you'll learn how to use services throughout your Medusa server. This includes both Medusa's services and your custom services.
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:::note
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Before using your service, make sure you run the `build` command:
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```bash npm2yarn
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npm run build
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```
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:::
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### In a Service
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To use your custom service in another custom service, you can have easy access to it in the dependencies injected to the constructor of your service:
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```ts
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class MyService extends TransactionBaseService {
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constructor(container) {
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super(container)
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this.helloService = container.helloService
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}
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// ...
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}
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```
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### In an Endpoint
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To use your custom service in an endpoint, you can use `req.scope.resolve` passing it the service’s registration name:
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```ts
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const helloService = req.scope.resolve("helloService")
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res.json({
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message: helloService.getMessage(),
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})
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```
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### In a Subscriber
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To use your custom service in a subscriber, you can have easy access to it in the subscriber’s dependencies injected to the constructor of your subscriber:
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```ts
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class MySubscriber {
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constructor({ helloService, eventBusService }) {
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this.helloService = helloService
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}
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// ...
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}
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```
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---
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## See Also
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- [Services Reference](/references/services/classes/AuthService)
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- [Create an Endpoint](../endpoints/add.md)
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