How to make param required in NestJS?

Use class-validator. Pipes are definitely made for that !

Example : create-user.dto.ts

import { IsNotEmpty } from 'class-validator';

export class CreateUserDto {
   @IsNotEmpty()
   password: string;
}

For more information see class-validator documentation : https://github.com/typestack/class-validator

And NestJS Pipes & Validation documentation : https://docs.nestjs.com/pipes https://docs.nestjs.com/techniques/validation

There hava a easy way to valide you parameter, https://docs.nestjs.com/techniques/validation