Getting started (Loopback4)

Have you installed Node.js?

Before you install LoopBack, make sure to download and install Node.js (version 8.9.x or higher), a JavaScript runtime.

Install Node.js

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Install LoopBack 4 CLI

The LoopBack 4 CLI is a command-line interface that can scaffold a project or extension. The CLI provides the fastest way to get started with a LoopBack 4 project that adheres to best practices.

$ npm install -g @loopback/cli
                    

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Create a new project

To create a new project, run the CLI as follows.

$ lb4 app
                    

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Answer the prompts as follows.

[?] Project name: getting-started
[?] Project description: Getting started tutorial
[?] Project root directory: (getting-started)
[?] Application class name: StarterApplication
[?] Select project build settings: Enable tslint, Enable prettier, Enable mocha, Enable loopbackBuild
                    

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Starting the project

The project comes with a "ping" route to test the project. Let's try it out by running the projects.

In a browser, visit http://127.0.0.1:3000/ping

$ cd getting-started
$ npm start
                    

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Add your own controller

Now that we have a basic project created, it’s time to add our own controller. Let’s add a simple “Hello World” controller as follows.

 $ lb4 controller
[?] Controller class name: hello
[?] What kind of controller would you like to generate? Empty Controller
    create src/controllers/hello.controller.ts
    update src/controllers/index.ts
Controller Hello was now created in src/controllers/
                    

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Paste the following contents into the file /src/controllers/hello.controller.ts.

import {get} from '@loopback/rest';
export class HelloController {
  @get('/hello')
  hello(): string {
    return 'Hello world!';
  }
}
                    

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Test your application

Start the application using npm start.

Visit http://127.0.0.1:3000/hello to see Hello world!