● バリデーション+クラス（型）の記述

A. class-validator

import { IsNotEmpty, IsEmail, Length } from 'class-validator';

export class CreateUserDto {
  @IsNotEmpty()
  @Length(10, 20)
  username: string;

  @IsEmail()
  email: string;

  @IsNotEmpty()
  password: string;
}

B. zod

import { z } from 'zod';

export const CreateUserDtoSchema = z.object({
  username: z.string().min(10).max(20),
  email: z.string().email(),
  password: z.string().nonempty(),
});

export type CreateUserDto = z.infer<typeof CreateUserDtoSchema>;

● バリデーションの実行

A. class-validator

import { IsNotEmpty, IsEmail, Length, validateOrReject } from 'class-validator';

export class CreateUserDto {
  @IsNotEmpty()
  @Length(10, 20)
  username: string;

  @IsEmail()
  email: string;

  @IsNotEmpty()
  password: string;

  constructor(username: string, email: string, password: string) {
    this.username = username;
    this.email = email;
    this.password = password;
    validateOrReject(this).catch(errors => {
      console.error('Validation failed:', errors);
      throw errors;
    });
  }
}

B. zod

import { z } from 'zod';

const CreateUserDtoSchema = z.object({
  username: z.string().min(10).max(20),
  email: z.string().email(),
  password: z.string().nonempty(),
});

export class CreateUserDto {
  username: string;
  email: string;
  password: string;

  constructor(username: string, email: string, password: string) {
    const parsedData = CreateUserDtoSchema.parse({ username, email, password });
    this.username = parsedData.username;
    this.email = parsedData.email;
    this.password = parsedData.password;
  }
}