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Step 5: Add Node Application Implementing 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 Nest Capabilities to your workspace

Run the following to add the capability to develop Nest applications in your workspace:

ng add @nrwl/nest

Create a Nest Application

Run the following to generate a new Nest application:

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

Nx will ask you a few questions, and, as with the Angular application, the defaults will 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.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:

  • ng serve api to serve the application
  • ng build api to build the application
  • ng test api to test the application

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

import { Module } from '@nestjs/common';

import { AppController } from './app.controller';
import { AppService } from './app.service';

@Module({
  imports: [],
  controllers: [AppController],
  providers: [AppService]
})
export 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:

import { Injectable } from '@nestjs/common';

interface Todo {
  title: string;
}

@Injectable()
export class AppService {
  todos: Todo[] = [{ title: 'Todo 1' }, { title: 'Todo 2' }];

  getData(): Todo[] {
    return this.todos;
  }

  addTodo() {
    this.todos.push({
      title: `New todo ${Math.floor(Math.random() * 1000)}`
    });
  }
}

Next, update the controller to invoke the service:

import { Controller, Get, Post } from '@nestjs/common';

import { AppService } from './app.service';

@Controller()
export class AppController {
  constructor(private readonly appService: AppService) {}

  @Get('todos')
  getData() {
    return this.appService.getData();
  }

  @Post('addTodo')
  addTodo() {
    return this.appService.addTodo();
  }
}

Quiz

Run "ng serve api" and open https://localhost:3333/api/todos. What do you see?

  • 404

  • [{"title":"Todo 1"},{"title":"Todo 2"}]

  • Blank screen