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Vibe Coding · 강의

사용자 계정과 로그인

가입과 인증 기능을 추가합니다.

사용자 계정과 로그인은(는) CoddyKit의 무료 Vibe Coding 강의입니다. 이것은 4개 중 4번째 강의입니다. 아래에서 전체 강의를 무료로 읽을 수 있으며, 내장 코드 에디터와 24/7 AI 튜터와 함께 브라우저에서 직접 실습할 수 있습니다. 이 강의는 Vibe Coding 학습 경로의 일부이며, 진행 상황이 웹과 CoddyKit 앱에 동기화됩니다. Vibe Coding 강의에는 총 4개의 강의가 포함되어 있습니다.

이 강의의 일부는 아직 번역되지 않았으며 영어로 표시됩니다.

Who Is Using Your App?

Your app stores data, but right now everyone shares the same data. A real product needs to know who each person is so each freelancer sees only their own clients and hours. That's what authentication (login) gives you.

Two related ideas: authentication answers "who are you?" and authorization answers "what are you allowed to do?" In this lesson you'll add both to your full-stack app with AI's help.

Don't Build Auth From Scratch

Authentication is security-critical and easy to get dangerously wrong. The pro move — even for experienced developers — is to use a trusted auth library or service rather than rolling your own.

Popular, AI-friendly options include Clerk, Supabase Auth, Auth0 and NextAuth/Auth.js. Let AI recommend one for your stack.

I'm adding login to my Next.js freelancer hours app. I do NOT want to build authentication from scratch.

Recommend ONE beginner-friendly auth solution (e.g. Clerk, Supabase Auth, or Auth.js). For your pick, explain:
- why it's safe and easy
- what sign-in methods it supports (email, Google, etc.)
- one sentence on how it fits Next.js

How Login Actually Works

The basic flow: a user enters credentials (or signs in with Google), the auth service verifies them and issues a session — a token that proves who they are on every later request.

Your app checks that session to decide what to show. You don't store raw passwords yourself; the auth service handles the scary parts.

Explain how the login flow works in plain language for my app, using the auth tool you recommended.

Walk through: user signs up, signs in, gets a session, and how my app uses that session on later requests to know who they are. Mention why I never store raw passwords myself.

Add Sign-Up and Sign-In Screens

Start with the visible part: pages where users can create an account and log in. Modern auth libraries provide ready-made components, so this is often just a few lines.

Ask AI to add the sign-up/sign-in UI and wire it into your app's navigation.

Set up sign-up and sign-in for my Next.js app using the auth tool we chose.

- add the sign-in and sign-up pages/components
- support email/password and Google sign-in
- add a 'Sign out' button in the header when logged in

Show me each file to create or edit and any environment variables I need. Keep secrets out of the code.

Protect Your Pages and Endpoints

A logged-out visitor shouldn't reach the dashboard or hit your data endpoints. Protecting routes means checking for a valid session and redirecting or rejecting if it's missing.

Ask AI to guard both your frontend pages and your API endpoints — both halves need protection, not just the screen.

Protect my app so only logged-in users can use it.

- redirect logged-out users away from the dashboard page to the sign-in page
- on the API side, reject requests to /api/entries that have no valid session, returning a 401

Show me the middleware or guards needed and explain why protecting the API matters even if the page is already protected.

A Tiny Session Check

At its core, route protection is a simple check: is there a valid session? Here's the idea in plain JavaScript — a guard that decides whether to allow or block a request. Run it to see both cases.

function handleRequest(session) {
  if (!session || !session.userId) {
    return { status: 401, body: "Please sign in" };
  }
  return { status: 200, body: "Welcome, user " + session.userId };
}

console.log(handleRequest(null));
console.log(handleRequest({ userId: 42 }));

Tie Data to the Logged-In User

Now the key step: each time entry must belong to a user, so people see only their own data. That means adding a userId to your records and filtering every query by the current user.

Ask AI to update your schema and endpoints so data is scoped to whoever is logged in.

Make my data per-user. Each TimeEntry and Client should belong to the logged-in user.

- add a userId field tied to the authenticated user
- when creating an entry, attach the current user's id
- when listing entries, only return rows belonging to the current user

Update the Prisma schema and the /api/entries endpoints. Give me the migration command too.

Authorization: Who Can Do What

Being logged in isn't enough — you must ensure a user can only touch their own records. Without this, anyone could edit someone else's entry by guessing an id. That's an authorization check, and it's a common AI blind spot.

Explicitly ask AI to verify ownership on update and delete.

Add ownership checks to my update and delete endpoints.

Before updating or deleting a TimeEntry, confirm it belongs to the currently logged-in user. If it belongs to someone else, return 403 Forbidden — never modify it.

Show the updated PUT and DELETE routes and explain why checking the session alone is not enough.

Show the User They're Logged In

Good apps make auth feel friendly: show the user's name or avatar, a clear "Sign out" button, and helpful states for loading and errors. This polish builds trust.

Ask AI to surface the logged-in user's info and handle the in-between states gracefully.

Polish the auth experience in my app.

- show the logged-in user's name and avatar in the header
- add a clean 'Sign out' action
- show a loading state while the session is being checked, so the UI doesn't flicker
- if sign-in fails, show a friendly message

Show me the component changes and keep the styling minimal.

Test the Whole Auth Flow

Before calling it done, walk the full journey: sign up, sign out, sign back in, add data, then sign in as a different user and confirm you see none of the first user's data. That proves both authentication and authorization work.

If something leaks across users, describe the exact steps to AI — it's a precise way to find the gap.

Help me test my app's auth end to end. Give me a step-by-step test checklist that includes:
- sign up, sign out, sign back in
- adding data as User A
- signing in as User B and confirming User B canNOT see User A's data
- trying to edit User A's entry while signed in as User B (should be blocked)

Tell me what correct behavior looks like at each step.

A Complete Full-Stack App

You did it: a frontend, a backend, a real database, and now secure user accounts — a genuinely full-stack app, built almost entirely by talking to AI. Each freelancer signs in and sees only their own clients and hours.

This is the foundation real products are built on. From here you can deploy it, add payments, or grow features — all with the same vibe-coding workflow you've practiced.

Quick Check

Lock in the security mindset.

Recap: Accounts and Login

You secured your full-stack app:

  • Authentication identifies the user; authorization controls what they can do
  • Use a trusted auth service (Clerk, Supabase Auth, Auth.js) — never roll your own
  • Protect both pages and API endpoints with session checks
  • Scope data per user with a userId and filter every query
  • Verify ownership before update/delete, and test across multiple users

Congratulations — you've built a complete full-stack app by talking to AI. Next courses cover deploying, payments and shipping it to real users!

자주 묻는 질문

“사용자 계정과 로그인” 강의는 무료인가요?

네 — “사용자 계정과 로그인” 전체 내용을 이 웹사이트에서 무료로 읽을 수 있습니다. 인터랙티브하게 실습하려면(내장 코드 에디터와 24/7 AI 튜터), CoddyKit PRO로 업그레이드하면 Vibe Coding 강의 전체를 잠금 해제할 수 있습니다. Vibe Coding 강의에는 총 4개의 강의가 포함되어 있습니다.

“사용자 계정과 로그인”에서 뭘 배우나요?

가입과 인증 기능을 추가합니다. 브라우저에서 직접 실행하는 실습 코드로 Vibe Coding을(를) 배우며, 24/7 AI 튜터가 강의를 진행하면서 질문에 답변해줍니다.

Vibe Coding을(를) 시작하는 데 경험이 필요한가요?

사전 경험은 필요하지 않습니다. CoddyKit의 Vibe Coding은(는) 초급자부터 고급 학습자까지를 위해 구성되어 있으므로, 여기서 시작하거나 처음부터 시작할 수 있으며 자신의 속도대로 진행할 수 있습니다. 이것은 4개 중 4번째 강의입니다.

“사용자 계정과 로그인” 강의는 얼마나 걸리나요?

대부분의 CoddyKit 강의는 약 5~10분이 소요됩니다. 각 강의는 간결하고 인터랙티브하여 꾸준한 진행이 가능하며, 웹과 앱에서 중단한 부분부터 바로 시작할 수 있습니다.

이 Vibe Coding 강의에서 코드를 작성하고 실행할 수 있나요?

네. 모든 Vibe Coding 강의에는 내장 코드 에디터가 포함되어 있으므로, 브라우저에서 바로 실제 코드를 작성하고 실행한 후 즉시 AI 피드백을 받을 수 있습니다 — 로컬 설정이 필요 없습니다.

이 강의의 모든 강의

  1. 인공지능과 함께 앱 계획하기
  2. 프론트엔드와 백엔드 함께 구축하기
  3. 데이터베이스 추가
  4. 사용자 계정과 로그인
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