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Create your app scaffolding

The LoopBack 4 CLI toolkit comes with templates that generate whole applications, as well as artifacts (for example, controllers, models, and repositories) for existing applications.

To generate your application using the toolkit, run the lb4 app command and fill out the on-screen prompts:

$ lb4 app
? Project name: todo-list
? Project description: A todo list API made with LoopBack 4.
? Project root directory: (todo-list)
? Application class name: (TodoListApplication)
? Select features to enable in the project:
 ◉ Enable eslint: add a linter with pre-configured lint rules
 ◉ Enable prettier: install prettier to format code conforming to rules
 ◉ Enable mocha: install mocha to run tests
 ◉ Enable loopbackBuild: use @loopback/build helpers (e.g. lb-eslint)
 ◉ Enable vscode: add VSCode config files
 ◉ Enable docker: include Dockerfile and .dockerignore
 ◉ Enable repositories: include repository imports and RepositoryMixin
 ◉ Enable services: include service-proxy imports and ServiceMixin
 # npm will install dependencies now
 Application todo-list was created in todo-list.

For this tutorial, when prompted with the options for enabling certain project features (LoopBack’s build, eslint, mocha, etc.), leave them all enabled.


After your application is generated, you will have a folder structure similar to the following:


Note that there might be extra files not listed here.

File Purpose
package.json Your application’s package manifest. See package.json for details.
tsconfig.json The TypeScript project configuration. See tsconfig.json for details.
.eslintrc.js ESLint configuration
.prettierrc Prettier configuration The Markdown-based README generated for your application.
LICENSE A copy of the MIT license. If you do not wish to use this license, please delete this file.
src/application.ts The application class, which extends RestApplication by default. This is the root of your application, and is where your application will be configured. It also extends RepositoryMixin which defines the datasource.
src/index.ts The starting point of your microservice. This file creates an instance of your application, runs the booter, then attempts to start the RestServer instance bound to the application.
src/sequence.ts An extension of the Sequence class used to define the set of actions to take during a REST request/response.
src/controllers/ Provides information about the controller directory, how to generate new controllers, and where to find more information.
src/controllers/ping.controller.ts A basic controller that responds to GET requests at /ping.
src/datasources/ Provides information about the datasources directory, how to generate new datasources, and where to find more information.
src/models/ Provides information about the models directory, how to generate new models, and where to find more information.
src/repositories/ Provides information about the repositories directory, how to generate new repositories, and where to find more information.
src/__tests__/ Please place your tests in this folder.
src/__tests__/acceptance/ping.controller.acceptance.ts An example test to go with the ping controller in src/controllers.
.mocharc.json Mocha configuration for running your application’s tests.

Next step: Add the Todo Model