Creating and Using DTOs

Create a new file in the src folder:

create-user.dto.ts

Add the following code:

export class CreateUserDto {
  name: string;
  age: number;
}

This DTO defines the structure of the data your application expects.

Now use it in your controller:

import { Controller, Post, Body } from '@nestjs/common';
import { CreateUserDto } from './create-user.dto';

@Controller('users')
export class UsersController {
  @Post()
  createUser(@Body() body: CreateUserDto) {
    return body;
  }
}

Here is what is happening:

• CreateUserDto: defines required fields;
• @Body(): extracts request data;
• CreateUserDto: ensures the data follows the defined structure.

Now send a request with data:

{
  "name": "Alice",
  "age": 30
}

The controller receives structured data based on the DTO.

Using DTOs keeps your data consistent and avoids repeating type definitions across your application.