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Vibe Coding · レッスン

シンプルにデータを保存する

ローカルストレージから本格的なデータベースまで学びます。

「シンプルにデータを保存する」はCoddyKit上の無料Vibe Codingレッスンです。 これはレッスン3/4です。 下記で完全なレッスンを無料で読むことができます。その後、ブラウザ内の組み込みコードエディタと24時間対応のAIチューターでハンズオン演習できます。 これはVibe Coding学習パスの一部であり、ウェブとCoddyKitアプリ全体で進捗が同期されます。 Vibe Codingコースには全4レッスンが含まれています。

このレッスンの一部はまだ翻訳されておらず、英語で表示されています。

Data That Sticks Around

Most apps need to remember things: your to-do list, your saved notes, the dark-mode setting you chose. Without storage, everything disappears when you refresh the page.

The good news: you can go from 'remembers nothing' to 'remembers everything' just by describing what to save — AI handles the storage code.

The Storage Ladder

There are levels of storage, from simplest to most powerful. Start low and climb only when you need to:

  • In memory — fast but forgotten on refresh
  • Local storage — saved in the user's browser, survives refresh
  • A database — shared across devices and users, the real deal

Telling AI which rung you want keeps your app as simple as possible.

Saving to the Browser

The easiest persistent storage is localStorage — a little notebook the browser keeps for your app. It's perfect for settings and small lists on a single device.

You don't need a server or account for this. A prompt like the one below adds it instantly.

Make my to-do list save to the browser's
localStorage so my tasks are still there after I
refresh the page. Load them automatically when the
page opens.

How localStorage Works

localStorage stores text by a name (a 'key'). To save objects or lists, you turn them into JSON text first, then turn them back when reading.

Run this to see the pattern AI uses: save a value, then read it back.

const settings = { theme: 'dark', fontSize: 16 };

const saved = JSON.stringify(settings);
console.log('Saved text:', saved);

const loaded = JSON.parse(saved);
console.log('Theme is:', loaded.theme);

When localStorage Isn't Enough

localStorage only lives in one browser on one device. If you want users to see their data on their phone and laptop, or share data between users, you need a database on a server.

That sounds scary, but tools make it easy. You'll describe what to store, and AI sets up the database calls.

Easy Databases for Vibe Coders

You don't need to run your own server. Hosted databases give you storage with almost no setup:

  • Supabase — a friendly database with built-in login, great with AI tools
  • Firebase — Google's real-time database
  • Airtable — a spreadsheet that acts like a database

Builders like Bolt, Lovable and Replit can connect these for you when you ask.

Adding a Database by Prompt

To add real storage, describe what you're saving and where. Naming Supabase (a popular choice) tells AI exactly which setup to generate.

This prompt turns a local-only app into one with a shared, persistent database.

Connect this app to Supabase. Create a table called
notes with columns: id, title, content, and
created_at. Update the app so saving a note inserts
a row, and the homepage loads all notes from the
table, newest first.

Thinking in Tables

A database stores data in tables — like spreadsheets with named columns. A 'notes' table might have a title, content, and a date. Each saved note is one row.

You don't need to master database design. Just tell AI what fields each thing has, and it builds the table for you.

Create, Read, Update, Delete

Almost every data app does four things, nicknamed CRUD: Create new items, Read them back, Update them, and Delete them. If your app can do all four, it's a real tool.

You can ask AI to add them one at a time, testing each before moving on.

Add full editing to my notes app: I should be able
to create a note, edit an existing note's title and
content, and delete a note with a confirm dialog.
Keep everything saved to Supabase.

Start Simple, Upgrade Later

The pro move is to start at the lowest rung that works. Building a quick prototype? localStorage. Need it on every device? Move up to a database. AI can even migrate you — 'switch my app from localStorage to Supabase.'

Don't over-engineer early. Match the storage to what your app actually needs today.

My app currently uses localStorage. Migrate it to
use Supabase instead so my data syncs across
devices, and move any existing local data into the
database on first load.

Backups and Not Losing Data

Data is precious — users get upset if it vanishes. Hosted databases like Supabase and Firebase keep backups for you, which is another reason to graduate from localStorage for anything important.

You can also let users export their own data as a safety net. Ask AI to add a one-click backup so nobody loses their work.

Add a "Download backup" button that exports all my
notes from the database as a JSON file, and an
"Import backup" option that restores them. This
way users never lose their data.

Quick Check

You built a notes app that uses the browser's localStorage. A user complains they can't see their notes when they open the app on their phone. What kind of storage do they actually need?

Recap: Storing Data Simply

You learned the storage ladder: in-memory, then localStorage for single-device persistence, then a real database for cross-device, shared data.

You saw how to save settings in the browser, when to upgrade to hosted databases like Supabase, how data lives in tables, and the CRUD actions every data app needs. Start simple and let AI upgrade you. Next: keeping your API keys and secrets safe.

よくある質問

「シンプルにデータを保存する」レッスンは無料ですか？

はい。「シンプルにデータを保存する」の完全なテキストはこのウェブで無料で読めます。インタラクティブに演習し（組み込みコードエディタと24時間対応のAIチューター）、Vibe Codingコースの残りをアンロックするには、CoddyKit PROにアップグレードしてください。 Vibe Codingコースには全4レッスンが含まれています。

「シンプルにデータを保存する」で何を学びますか？

ローカルストレージから本格的なデータベースまで学びます。 ブラウザで直接実行するハンズオンコードでVibe Codingを演習し、24時間対応のAIチューターがレッスンを進める中での質問に答えます。

Vibe Codingを始めるのに経験は必要ですか？

事前経験は必要ありません。CoddyKitのVibe Codingは初級者から上級者向けに構成されているため、ここから始めるか最初から始めて、自分のペースで進むことができます。 これはレッスン3/4です。

「シンプルにデータを保存する」レッスンにはどのくらい時間がかかりますか？

ほとんどのCoddyKitレッスンは約5～10分かかります。各レッスンはコンパクトでインタラクティブなので、着実に進歩し、ウェブとアプリ全体で正確に前回の場所から再開できます。

このVibe Codingレッスンでコードを書いて実行できますか？

はい。すべてのVibe Codingレッスンに組み込みコードエディタが含まれているため、ブラウザでリアルコードを書いて実行し、即座のAIフィードバックを取得できます。ローカル設定は不要です。

このコースのすべてのレッスン

  1. APIと対話する
  2. ファイルの読み書き
  3. シンプルにデータを保存する
  4. シークレットとキーを扱う
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