NestJS review

import "reflect-metadata";
import { Body, Controller, Get, HttpCode, Module, NotFoundException, Param, ParseIntPipe, Post, ValidationPipe } from "@nestjs/common";
import { NestFactory } from "@nestjs/core";
import { ArrayMaxSize, IsArray, IsNumber, IsOptional, IsString, Length, Min } from "class-validator";

class CreateItemDto {
  @IsString() @Length(1, 100) name: string;
  @IsNumber() @Min(0) price: number;
  @IsOptional() @IsArray() @IsString({ each: true }) @ArrayMaxSize(10) tags?: string[];
}

// 100 items kept in memory, so the test measures the framework, not a database.
const items = new Map<number, object>();
for (let i = 1; i <= 100; i++) items.set(i, { id: i, name: `Item ${i}`, price: i * 1.5, tags: ["sample"] });
let nextId = 101;

@Controller()
class ItemsController {
  @Get("health")
  health() { return { status: "ok" }; }

  @Get("items/:id")
  get(@Param("id", ParseIntPipe) id: number) {
    const item = items.get(id);
    if (!item) throw new NotFoundException("Not found");
    return item;
  }

  @Post("items")
  @HttpCode(201)
  create(@Body() body: CreateItemDto) {
    const item = { id: nextId++, ...body };
    items.set(item.id, item);
    return item;
  }
}

@Module({ controllers: [ItemsController] })
class AppModule {}

async function bootstrap() {
  const app = await NestFactory.create(AppModule, { logger: ["error", "warn"] });
  app.useGlobalPipes(new ValidationPipe({ whitelist: true, forbidNonWhitelisted: true }));
  await app.listen(Number(process.env.PORT ?? 3000), "127.0.0.1");
}
bootstrap();