@loopback/docs/site/Controller-generator.md

Documentation for LoopBack 4

---
lang: en
title: 'Controller generator'
keywords: LoopBack 4.0, LoopBack 4
tags:
sidebar: lb4_sidebar
permalink: /doc/en/lb4/Controller-generator.html
summary:
---

{% include content/generator-create-app.html lang=page.lang %}

### Synopsis

Adds a new empty controller to a LoopBack application.

```sh
lb4 controller [options] [<name>]
```

### Options

`--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.

{% include_relative includes/CLI-std-options.md %}

### Arguments

`<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:

```ts
// 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

{% include warning.html content= " If you do not have a model and repository to
select, then you will receive an error! " lang=page.lang
%}

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

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

export class TodoController {
  constructor(
    @inject('repositories.TodoRepository')
    public todoRepository: TodoRepository,
  ) {}

  @post('/todo')
  async create(@requestBody() obj: Todo): Promise<Todo> {
    return await this.todoRepository.create(obj);
  }

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

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

  @patch('/todo')
  async updateAll(
    @param.query.string('where') where: Where,
    @reqeustBody() obj: Todo,
  ): Promise<number> {
    return await this.todoRepository.updateAll(where, obj);
  }

  @del('/todo')
  async deleteAll(@param.query.string('where') where: Where): Promise<number> {
    return await this.todoRepository.deleteAll(where);
  }

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

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

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