From e469093f9efd3957229ab0a89f6d7ad0c31ea569 Mon Sep 17 00:00:00 2001
From: chimame <rito.tamata@gmail.com>
Date: Mon, 9 Dec 2024 21:18:47 +0900
Subject: [PATCH] Change AsyncLocalStorage to an example of using Context
 Storage Middleware

---
 README.md | 62 ++++++++++++++++---------------------------------------
 1 file changed, 18 insertions(+), 44 deletions(-)

diff --git a/README.md b/README.md
index c73567b..35979b6 100644
--- a/README.md
+++ b/README.md
@@ -338,70 +338,44 @@ export const getLoadContext: GetLoadContext = ({ context }) => {
 ## AsyncLocalStorage
 
 You can use AsyncLocalStorage, which is supported by Node.js, Cloudflare Workers, etc.
+You can easily store context using Hono's Context Storage Middleware.
 
 ```ts
-// server/context/index.ts
-import { AsyncLocalStorage } from 'node:async_hooks'
-
-export const context = new AsyncLocalStorage<ReturnType<typeof createContext>>()
+// server/index.ts
+import { Hono } from 'hono'
+import { contextStorage } from 'hono/context-storage'
 
-export const createContext = (req: Request) => {
-  const serverContext = {
-    headers: req.headers,
-    key: 'your-value',
-    // db: new DatabaseConnection() // It's also a good idea to store database connections, etc.
+export interface Env {
+  Variables: {
+    headers: Headers
+    key: string
+    // db: DatabaseConnection // It's also a good idea to store database connections, etc.
   }
-
-  return serverContext
 }
 
-const getStore = () => {
-  const store = context.getStore()
+const app = new Hono<Env>()
 
-  if (!store) {
-    throw new Error('No context store found')
-  }
-
-  return store
-}
-
-export const getHeaders = () => {
-  return getStore().headers()
-}
-
-// export const db = () => {
-//   return getStore().db
-// }
-```
-
-Store the context created in AsyncLocalStorage with Hono.
-
-```ts
-// server/index.ts
-import { Hono } from 'hono'
-import { context, createContext } from './contexts'
-
-const app = new Hono()
+app.use(contextStorage())
 
 app.use(async (c, next) => {
-  const serverContext = createContext(c.req.raw)
+  c.set('headers', c.req.raw.headers)
+  c.set('message', 'Hello!')
 
-  await context.run(serverContext, async () => {
-    await next()
-  })
+  await next()
 })
 
 export default app
 ```
 
-You can retrieve and process the context stored in AsyncLocalStorage from Remix as follows.
+You can retrieve and process the context saved in Hono from Remix as follows:
 
 ```ts
 // app/routes/_index.tsx
-import { getHeaders } from 'server/context' // It can be called anywhere for server-side processing.
+import type { Env } from 'server'
+import { getContext } from 'hono/context-storage' // It can be called anywhere for server-side processing.
 
 export const loader = () => {
-  const cookie = getHeaders().get('Cookie')
+  const cookie = getContext<Env>().headers.get('Cookie')
 }
 ```