From 5545345a7a1a51333d518d5a5cb8580d74ff2492 Mon Sep 17 00:00:00 2001
From: nflaig <nflaig@protonmail.com>
Date: Thu, 11 Jun 2020 15:04:56 +0200
Subject: [PATCH] feat(core): add services to component artifacts

- add services property to Component interface
- allow to contribute services from a component to
an application
- automatically bind service to application

Signed-off-by: nflaig <nflaig@protonmail.com>
---
 .../src/__tests__/unit/application.unit.ts    | 29 +++++++++++++++++++
 packages/core/src/application.ts              |  5 +++-
 packages/core/src/component.ts                | 17 ++++++++++-
 3 files changed, 49 insertions(+), 2 deletions(-)

diff --git a/packages/core/src/__tests__/unit/application.unit.ts b/packages/core/src/__tests__/unit/application.unit.ts
index 61e76b5285e9..8f710233037c 100644
--- a/packages/core/src/__tests__/unit/application.unit.ts
+++ b/packages/core/src/__tests__/unit/application.unit.ts
@@ -171,6 +171,35 @@ describe('Application', () => {
       expect(binding.tagNames).to.containEql('foo');
     });
 
+    it('binds services from a component', () => {
+      class MyService {}
+
+      class MyComponentWithServices implements Component {
+        services = [MyService];
+      }
+
+      app.component(MyComponentWithServices);
+
+      expect(
+        app.getBinding('services.MyService').valueConstructor,
+      ).to.be.exactly(MyService);
+    });
+
+    it('binds services with @bind from a component', () => {
+      @bind({scope: BindingScope.TRANSIENT, tags: ['foo']})
+      class MyService {}
+
+      class MyComponentWithServices implements Component {
+        services = [MyService];
+      }
+
+      app.component(MyComponentWithServices);
+
+      const binding = app.getBinding('services.MyService');
+      expect(binding.scope).to.eql(BindingScope.TRANSIENT);
+      expect(binding.tagNames).to.containEql('foo');
+    });
+
     it('honors tags when binding providers from a component', () => {
       @bind({tags: ['foo']})
       class MyProvider implements Provider<string> {
diff --git a/packages/core/src/application.ts b/packages/core/src/application.ts
index a6d525776f8a..acd25c063e1d 100644
--- a/packages/core/src/application.ts
+++ b/packages/core/src/application.ts
@@ -451,7 +451,7 @@ export class Application extends Context implements LifeCycleObserver {
    * ```
    */
   public service<S>(
-    cls: Constructor<S | Provider<S>>,
+    cls: ServiceOrProviderClass<S>,
     nameOrOptions?: string | ServiceOptions,
   ): Binding<S> {
     const options = toOptions(nameOrOptions);
@@ -602,6 +602,9 @@ export interface ApplicationConfig {
 // eslint-disable-next-line @typescript-eslint/no-explicit-any
 export type ControllerClass<T = any> = Constructor<T>;
 
+// eslint-disable-next-line @typescript-eslint/no-explicit-any
+export type ServiceOrProviderClass<T = any> = Constructor<T | Provider<T>>;
+
 /**
  * Type description for `package.json`
  */
diff --git a/packages/core/src/component.ts b/packages/core/src/component.ts
index 77fd8e4906be..7ef70aa3f943 100644
--- a/packages/core/src/component.ts
+++ b/packages/core/src/component.ts
@@ -10,7 +10,11 @@ import {
   createBindingFromClass,
   Provider,
 } from '@loopback/context';
-import {Application, ControllerClass} from './application';
+import {
+  Application,
+  ControllerClass,
+  ServiceOrProviderClass,
+} from './application';
 import {LifeCycleObserver} from './lifecycle';
 import {Server} from './server';
 
@@ -71,6 +75,11 @@ export interface Component {
 
   lifeCycleObservers?: Constructor<LifeCycleObserver>[];
 
+  /**
+   * An array of service or provider classes
+   */
+  services?: ServiceOrProviderClass[];
+
   /**
    * An array of bindings to be aded to the application context.
    *
@@ -137,4 +146,10 @@ export function mountComponent(app: Application, component: Component) {
       app.lifeCycleObserver(observer);
     }
   }
+
+  if (component.services) {
+    for (const service of component.services) {
+      app.service(service);
+    }
+  }
 }