NestJS Response DTO Mapper

👀 Response to DTO mapper for NestJS and Swagger with class-transformer

Installation

yarn add nestjs-response-dto-mapper

Usage

1. Create a DTO class using at least one class-transformer decorator for each field:

import { ApiProperty } from '@nestjs/swagger';
import { Expose } from 'class-transformer';

export class UserDto {
  @Expose()
  @ApiProperty({ description: 'ID' }) // or you can use `@nestjs/swagger` CLI plugin
  id: number;

  @Expose()
  @ApiProperty({ description: 'First name' })
  firstName: string;

  @Expose()
  @ApiProperty({ description: 'Last name' })
  lastName: string;

  @Expose()
  @ApiProperty({ description: 'Email' })
  email: string;

  @Expose()
  @ApiProperty({ description: 'Phone number' })
  phone: string;
}

2. Decorate each controller method with the MapResponseToDto decorator:

import { Controller, Get } from '@nestjs/common';
import { ApiOperation } from '@nestjs/swagger';
import { MapResponseToDto } from 'nestjs-response-dto-mapper';
import { User as UserModel } from '@prisma/client'; // for example

import { UserDto } from './dto/user.dto';

@Controller('user')
export class UserController {
  @Get()
  @ApiOperation({ summary: 'List all users' }) // or you can use @nestjs/swagger CLI plugin
  @MapResponseToDto(UserDto, { /* ApiOkResponse decorator options */ isArray: true })
  findMany(): UserModel[] {
    // for example
    return [
      {
        id: 1,
        firstName: 'Example',
        lastName: 'Example',
        email: '[email protected]',
        phone: '+99999999999',
        password: '$2y$10$gN9UIb8EjkhNWxu8iRJQOe/kAk1TqhtJ1M72DKx.BrpgyAe7XURhq',
        rights: 'user'
      },
      {
        id: 2,
        firstName: 'Test',
        lastName: 'Test',
        email: '[email protected]',
        phone: '+88888888888',
        password: '$2y$10$Mrh1URLy.Fo8tmBZtaPd5OR.1gDaPvU7GX02./uK9kKz.Skoc2C5y',
        rights: 'user'
      },
       {
        id: 3,
        firstName: 'Admin',
        lastName: 'Admin',
        email: '[email protected]',
        phone: '+88005553535',
        password: '$2y$10$qi8oDsLM88XMw4ZStIE7pOG6yZNceqDTVOp0ajLIOk2ttyIcPF9r.',
        rights: 'admin'
      }
    ]
  }
}

3. Run and test it!

Swagger schema:

Response:

[
  {
    "id": 1,
    "firstName": "Example",
    "lastName": "Example",
    "email": "[email protected]",
    "phone": "99999999999"
  },
  {
    "id": 2,
    "firstName": "Test",
    "lastName": "Test",
    "email": "[email protected]",
    "phone": "+88888888888"
  },
    {
    "id": 3,
    "firstName": "Admin",
    "lastName": "Admin",
    "email": "[email protected]",
    "phone": "+88005553535"
  }
]

Troubleshooting

I use the @nestjs/swagger CLI Plugin and my method returns an array of objects, but the swagger does not display the method summary and response schema Try casting the return value to the dto type:

// controller...
export class UserController {
  // ...
  findMany(): UserDto[] {
    // findMany returns UserModel[]
    return this.userService.findMany() as UserDto[];
  }
}

License

MIT