🚀 Next.js 12장: Route Handlers — 외부와 대화하는 창구

// app/api/posts/route.ts
 
import { NextRequest, NextResponse } from 'next/server'
import { db } from '@/lib/db'
 
// GET /api/posts — 게시글 목록 조회
export async function GET(request: NextRequest) {
  // URL 쿼리 파라미터 읽기
  const { searchParams } = request.nextUrl
  const page = searchParams.get('page') ?? '1'
  const limit = searchParams.get('limit') ?? '10'
 
  const posts = await db.posts.findMany({
    skip: (parseInt(page) - 1) * parseInt(limit),
    take: parseInt(limit),
    orderBy: { createdAt: 'desc' },
  })
 
  // NextResponse.json()으로 JSON 응답 반환
  return NextResponse.json({
    data: posts,
    page: parseInt(page),
  })
}
 
// POST /api/posts — 게시글 생성 (외부 클라이언트용)
export async function POST(request: NextRequest) {
  const body = await request.json()    // Request Body 파싱
 
  // 간단한 유효성 검사
  if (!body.title || !body.content) {
    // 에러 응답: 두 번째 인자로 상태 코드 지정
    return NextResponse.json(
      { error: '제목과 내용은 필수예요' },
      { status: 400 }
    )
  }
 
  const post = await db.posts.create({ data: body })
 
  return NextResponse.json({ data: post }, { status: 201 })  // 201 Created
}

// app/api/posts/[id]/route.ts
 
import { NextRequest, NextResponse } from 'next/server'
 
type Params = { params: Promise<{ id: string }> }
 
// GET /api/posts/123
export async function GET(request: NextRequest, { params }: Params) {
  const { id } = await params  // Next.js 15: params는 Promise
 
  const post = await db.posts.findUnique({ where: { id } })
 
  if (!post) {
    return NextResponse.json({ error: '게시글을 찾을 수 없어요' }, { status: 404 })
  }
 
  return NextResponse.json({ data: post })
}
 
// PUT /api/posts/123 — 게시글 수정
export async function PUT(request: NextRequest, { params }: Params) {
  const { id } = await params
  const body = await request.json()
 
  const updated = await db.posts.update({
    where: { id },
    data: body,
  })
 
  return NextResponse.json({ data: updated })
}
 
// DELETE /api/posts/123 — 게시글 삭제
export async function DELETE(request: NextRequest, { params }: Params) {
  const { id } = await params
 
  await db.posts.delete({ where: { id } })
 
  return new NextResponse(null, { status: 204 })  // 204 No Content
}

// app/api/posts/route.ts — CORS 헤더 추가
export async function GET(request: NextRequest) {
  const posts = await db.posts.findMany()
 
  return NextResponse.json({ data: posts }, {
    headers: {
      'Access-Control-Allow-Origin': 'https://our-mobile-app.com',
      'Access-Control-Allow-Methods': 'GET, POST, PUT, DELETE, OPTIONS',
      'Access-Control-Allow-Headers': 'Content-Type, Authorization',
    },
  })
}
 
// OPTIONS preflight 요청도 처리
export async function OPTIONS() {
  return new NextResponse(null, {
    headers: {
      'Access-Control-Allow-Origin': '*',
      'Access-Control-Allow-Methods': 'GET, POST, PUT, DELETE, OPTIONS',
    },
  })
}

// app/api/webhooks/stripe/route.ts
import { headers } from 'next/headers'
import Stripe from 'stripe'
 
const stripe = new Stripe(process.env.STRIPE_SECRET_KEY!)
 
export async function POST(request: NextRequest) {
  // Raw body가 필요한 Stripe 서명 검증을 위해 text()로 받음
  const body = await request.text()
  const headersList = await headers()
  const signature = headersList.get('stripe-signature')!
 
  let event: Stripe.Event
  try {
    // Stripe가 요청에 서명을 넣어주는데, 이걸 검증해야 가짜 요청을 걸러낼 수 있음
    event = stripe.webhooks.constructEvent(
      body,
      signature,
      process.env.STRIPE_WEBHOOK_SECRET!
    )
  } catch (err) {
    console.error('웹훅 서명 검증 실패:', err)
    return NextResponse.json({ error: 'Invalid signature' }, { status: 400 })
  }
 
  // 이벤트 타입별 처리
  switch (event.type) {
    case 'payment_intent.succeeded':
      const paymentIntent = event.data.object as Stripe.PaymentIntent
      await db.orders.update({
        where: { paymentId: paymentIntent.id },
        data: { status: 'PAID' },
      })
      break
    case 'customer.subscription.deleted':
      // 구독 취소 처리
      break
  }
 
  return NextResponse.json({ received: true })
}

// app/api/export/posts/route.ts — CSV 파일 다운로드
export async function GET() {
  const posts = await db.posts.findMany()
 
  // CSV 문자열 생성
  const csv = [
    'id,title,createdAt',
    ...posts.map((p) => `${p.id},"${p.title}",${p.createdAt}`),
  ].join('\n')
 
  return new NextResponse(csv, {
    headers: {
      'Content-Type': 'text/csv; charset=utf-8',
      'Content-Disposition': 'attachment; filename="posts.csv"',
    },
  })
}

{ "error": "Method Not Allowed" }

// app/api/users/[id]/route.ts
export async function DELETE(
  request: NextRequest,
  { params }: { params: Promise<{ id: string }> }
) {
  const { id } = await ______
  await db.users.delete({ where: { id } })
  return new NextResponse(null, { status: ______ })
}