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Edge Computing with Cloudflare Workers & Deno · レッスン

Cloudflare KVストア

エッジでのキー・バリューストレージにCloudflare Workers KVを活用します。キャッシュや設定に適しています

「Cloudflare KVストア」はCoddyKit上の無料Edge Computing with Cloudflare Workers & Denoレッスンです。 これはレッスン1/4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Edge Computing with Cloudflare Workers & Deno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。 Edge Computing with Cloudflare Workers & Deno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。

Edge Data with KV Store

Welcome to Cloudflare KV! It's a highly distributed key-value store that runs on Cloudflare's global network, right at the edge.

This means your data is stored incredibly close to your users, leading to extremely fast access and low latency. It's perfect for dynamic content, configuration, and caching.

How Key-Value Works

A key-value store is like a simple dictionary or map. You store data as unique key-value pairs. The key is a unique identifier (a string), and the value is the data associated with that key.

  • Keys: Think of them as unique names, like "user_id_123" or "website_config".
  • Values: These are the actual data, which can be strings, numbers, JSON objects (as strings), or even binary data.

KV's Edge Advantages

Why use KV at the edge?

  • Speed: Data is served from the nearest Cloudflare data center, reducing latency.
  • Simplicity: It's schemaless, making it easy to store and retrieve data without complex database schemas.
  • Scalability: Automatically scales to handle massive traffic and global distribution.
  • Cost-Effective: Often more economical for specific use cases compared to traditional databases.

Practical KV Applications

Cloudflare KV is versatile for many edge-specific tasks:

  • Caching: Storing frequently accessed API responses, HTML snippets, or static assets.
  • Configuration: Managing dynamic feature flags, A/B test settings, or redirect rules.
  • Personalization: Storing simple user preferences like theme choices or language settings.
  • Rate Limiting: Keeping track of request counts per user or IP address.

Creating a KV Namespace

Before using KV, you need to create a Namespace. A namespace is a logical container for your key-value pairs, keeping your data organized.

You can create a new KV Namespace through the Cloudflare dashboard or using the Wrangler CLI (Cloudflare's command-line tool).

Binding KV to Your Worker

To use a KV Namespace in your Worker, you must bind it in your wrangler.toml configuration file. This makes the KV namespace accessible as a global variable in your Worker script.

Here's how you define a binding:

name = "my-worker"
main = "src/index.js"
compatibility_date = "2024-01-01"

[[kv_namespaces]]
binding = "MY_KV_STORE" # The variable name in your Worker
id = "YOUR_NAMESPACE_ID" # Get this from Cloudflare dashboard

Storing Data with `put`

The put() method is used to store data in your KV Namespace. It takes a key and a value as arguments. Values can be strings, ArrayBuffers, or ReadableStreams.

Try running this example Worker:

export default {
  async fetch(request, env, ctx) {
    const key = "user_setting";
    const value = "dark_mode";
    
    // Store the value in the MY_KV_STORE namespace
    await env.MY_KV_STORE.put(key, value);
    
    return new Response(`Stored '${value}' for key '${key}'`);
  },
};

Retrieving Data with `get`

To retrieve a value, you use the get() method, providing the key. If the key doesn't exist, get() will return null.

This example tries to retrieve the setting we just stored:

export default {
  async fetch(request, env, ctx) {
    const key = "user_setting";
    
    // Retrieve the value from the MY_KV_STORE namespace
    const value = await env.MY_KV_STORE.get(key);
    
    if (value === null) {
      return new Response(`Key '${key}' not found.`, { status: 404 });
    }
    
    return new Response(`Retrieved: '${value}'`);
  },
};

Removing Data with `delete`

If you need to remove a key-value pair from your namespace, use the delete() method with the key you wish to remove.

Here's how to delete the stored setting:

export default {
  async fetch(request, env, ctx) {
    const key = "user_setting";
    
    // Delete the key-value pair from the MY_KV_STORE namespace
    await env.MY_KV_STORE.delete(key);
    
    return new Response(`Key '${key}' deleted.`);
  },
};

Listing Keys in KV

Cloudflare KV also provides a list() method to retrieve a list of keys within a namespace. This can be useful for administrative tasks or for understanding the contents of your KV store.

It often returns an object containing an array of keys and a list_complete boolean.

// Example of listing keys (inside a Worker's fetch handler)
const { keys } = await env.MY_KV_STORE.list();

// To get just the names:
const keyNames = keys.map(k => k.name);
console.log(keyNames);

KV Operations Check

Which of the following statements about Cloudflare KV are true?

Recap: Cloudflare KV Store

In this lesson, you've learned about Cloudflare KV, a powerful key-value store optimized for the edge. We covered:

  • What KV is and its advantages for low-latency data access.
  • Common use cases like caching and configuration.
  • How to create a KV Namespace and bind it to a Cloudflare Worker.
  • The core operations: put() to store, get() to retrieve, and delete() to remove data.

KV is a fundamental tool for building fast, scalable, and efficient edge applications!

よくある質問

「Cloudflare KVストア」レッスンは無料ですか？

はい。「Cloudflare KVストア」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）、Edge Computing with Cloudflare Workers & Deno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。 Edge Computing with Cloudflare Workers & Denoコースには全4レッスンが含まれています。

「Cloudflare KVストア」で何を学びますか？

エッジでのキー・バリューストレージにCloudflare Workers KVを活用します。キャッシュや設定に適しています ブラウザで直接実行するハンズオンコードでEdge Computing with Cloudflare Workers & Deno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。

Edge Computing with Cloudflare Workers & Deno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Edge Computing with Cloudflare Workers & Deno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1/4です。

「Cloudflare KVストア」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Edge Computing with Cloudflare Workers & Deno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Edge Computing with Cloudflare Workers & Deno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. Cloudflare KVストア
  2. Durable Objectsの概要
  3. Denoとエッジストレージの統合
  4. エッジでD1 SQLを使ってクエリする
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