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Adds a new empty controller to a LoopBack application.

lb4 controller [options] [<name>]


--controllerType : Type of the controller.

Valid types are BASIC and REST. BASIC corresponds to an empty controller, whereas REST corresponds to REST controller with CRUD methods.

Standard options

-h, --help
Print the generator’s options and usage.
Do not remember prompt answers. Default is false.
Do not automatically install dependencies. Default is false.
-c, --config
JSON file name or value to configure options
Format generated code using npm run lint:fix

For example,

lb4 app --config config.json
lb4 app --config {"name":"my-app"}
cat config.json | lb4 app --config stdin
lb4 app --config stdin < config.json
lb4 app --config stdin << EOF
> {"name":"my-app"}
-y, --yes
Skip all confirmation prompts with default or provided value


<name> - Optional name of the controller to create as an argument to the command.  If provided, the tool will use that as the default when it prompts for the name.

Interactive Prompts

The tool will prompt you for:

  • Name of the controller. If the name had been supplied from the command line, the prompt is skipped and the controller is built with the name from the command-line argument.
  • Type of the controller. You can select from the following types:
    • Empty Controller - An empty controller definition
    • REST Controller with CRUD Methods - A controller wired up to a model and repository definition, with pre-defined CRUD methods.

Empty Controller

If you select the Empty Controller, it will generate a nearly-empty template based on the given name:

// Uncomment these imports to begin using these cool features!

// import {inject} from '@loopback/context';

export class FooController {
  constructor() {}

REST Controller with CRUD Methods

If you select the REST Controller with CRUD Methods type, you will then be asked to select:

  • The model to use for the CRUD function definitions
  • The repository for this model that provides datasource connectivity
  • The REST path name to host the endpoints on

The prompts that list out the models and repositories to choose from to build the controller with are chosen from the existing model/repository files on disc. From the LoopBack 4 project that the CLI is run in, the CLI tool will search for the following files in the LoopBack 4 project it runs in:

  • src/repositories/*.repository.ts
  • src/repositores/*.repository.js
  • src/models/*.model.ts
  • src/models/*.model.js

Files that match these patterns will then be identified based on the string before the first . separator. For example, file models/product.model.ts is identified as a source of Product model.

Here’s an example of what the template will produce given a Todo model and a TodoRepository:

import {Filter, Where, repository} from '@loopback/repository';
import {post, param, get, patch, del, requestBody} from '@loopback/rest';
import {Todo} from '../models';
import {TodoRepository} from '../repositories';

export class TodoController {
    @repository(TodoRepository) public todoRepository: TodoRepository,
  ) {}

  async create(@requestBody() obj: Todo): Promise<Todo> {
    return await this.todoRepository.create(obj);

  async count(@param.query.string('where') where?: Where): Promise<number> {
    return await this.todoRepository.count(where);

  async find(@param.query.string('filter') filter?: Filter): Promise<Todo[]> {
    return await this.todoRepository.find(filter);

  async updateAll(
    @requestBody() obj: Todo,
    @param.query.string('where') where?: Where,
  ): Promise<number> {
    return await this.todoRepository.updateAll(obj, where);

  async findById(@param.path.number('id') id: number): Promise<Todo> {
    return await this.todoRepository.findById(id);

  async updateById(
    @param.path.number('id') id: number,
    @requestBody() obj: Todo,
  ): Promise<boolean> {
    return await this.todoRepository.updateById(id, obj);

  async deleteById(@param.path.number('id') id: number): Promise<boolean> {
    return await this.todoRepository.deleteById(id);