Angular Nx Tutorial - Step 5: Add Node Application Implementing an API

The requests fail because the API has not been created yet. Using Nx you can develop node applications next to your Angular applications. You can use same commands to run and test them. You can share code between the backend and the frontend. Use this capability to implement the API service.

Add NestJS plugin to your workspace

Nx is an extensible framework with plugins for many modern tools and frameworks. To see some plugins, run nx list:

>  NX  Installed plugins:

  @nrwl/angular (executors,generators)
  @nrwl/cypress (executors,generators)
  @nrwl/jest (executors,generators)
  @nrwl/workspace (executors,generators)


>  NX  Also available:

  @nrwl/express (executors,generators)
  @nrwl/linter (builders)
  @nrwl/nest (executors,generators)
  @nrwl/next (executors,generators)
  @nrwl/node (executors,generators)
  @nrwl/nx-plugin (executors,generators)
  @nrwl/react (executors,generators)
  @nrwl/storybook (executors,generators)
  @nrwl/web (executors,generators)


>  NX  Community plugins:

  @angular-architects/ddd - Nx plugin for structuring a monorepo with domains and layers
  @offeringsolutions/nx-karma-to-jest - Nx plugin for replacing karma with jest in an Nx workspace
  @dev-thought/nx-deploy-it - Nx plugin to deploy applications on your favorite cloud provider

Now run npx nx list @nrwl/nest, and you will see:

>  NX   NOTE  @nrwl/nest is not currently installed

  Use "yarn add --dev @nrwl/nest" to add new capabilities

Add the dependency:

npm install --save-dev @nrwl/nest

yarn add --dev @nrwl/nest

@nrwl/nest also added @nrwl/node. Run nx list @nrwl/nest and nx list @nrwl/node to see what those plugins provide.

Create a NestJS application

Run the following to generate a new Nest application:

npx nx g @nrwl/nest:app api --frontendProject=todos

Nx asks you a few questions, and, as with the Angular application, the defaults work well here.

After this is done, you should see something like this:

myorg/
├── apps/
│   ├── todos/
│   ├── todos-e2e/
│   └── api/
│       ├── src/
│       │   ├── app/
│       │   │   ├── app.controller.ts
│       │   │   ├── app.controller.spec.ts
│       │   │   ├── app.module.ts
│       │   │   ├── app.service.ts
│       │   │   └── app.service.spec.ts
│       │   ├── assets/
│       │   ├── environments/
│       │   │   ├── environment.ts
│       │   │   └── environment.prod.ts
│       │   └── main.ts
│       ├── jest.conf.js
│       ├── proxy.conf.json
│       ├── tsconfig.app.json
│       ├── tsconfig.json
│       ├── tsconfig.spec.json
│       └── tslint.json
├── libs/
├── angular.json
├── nx.json
├── package.json
├── tools/
├── tsconfig.base.json
└── tslint.json

The apps directory is where Nx places anything you can run: frontend applications, backend applications, e2e test suites. That's why the api application appeared there.

You can run:

npx nx serve api to serve the application
npx nx build api to build the application
npx nx test api to test the application

Open apps/api/src/app/app.module.ts.

1import { Module } from '@nestjs/common';
2
3import { AppController } from './app.controller';
4import { AppService } from './app.service';
5
6@Module({
7  imports: [],
8  controllers: [AppController],
9  providers: [AppService],
10})
11export class AppModule {}

We recommend using the Nest framework when creating node applications. Nest is a powerful framework which helps develop robust node applications. You can also use Express or any node libraries with Nx.

In this case you have an application that registers a service and a controller. Services in Nest are responsible for the business logic, and controllers are responsible for implementing Http endpoints.

Update apps/api/src/app/app.service.ts:

1import { Injectable } from '@nestjs/common';
2
3interface Todo {
4  title: string;
5}
6
7@Injectable()
8export class AppService {
9  todos: Todo[] = [{ title: 'Todo 1' }, { title: 'Todo 2' }];
10
11  getData(): Todo[] {
12    return this.todos;
13  }
14
15  addTodo() {
16    this.todos.push({
17      title: `New todo ${Math.floor(Math.random() * 1000)}`,
18    });
19  }
20}

Next, update the controller to invoke the service:

1import { Controller, Get, Post } from '@nestjs/common';
2
3import { AppService } from './app.service';
4
5@Controller()
6export class AppController {
7  constructor(private readonly appService: AppService) {}
8
9  @Get('todos')
10  getData() {
11    return this.appService.getData();
12  }
13
14  @Post('addTodo')
15  addTodo() {
16    return this.appService.addTodo();
17  }
18}