feat(serve-static): add onFound option (#198)

Author: yusukebe

README.md

@@ -194,6 +194,22 @@ app.use(
 )
 ```
 
+#### `onFound`
+
+You can specify handling when the requested file is found with `onFound`.
+
+```ts
+app.get(
+  '/static/*',
+  serveStatic({
+    // ...
+    onFound: (_path, c) => {
+      c.header('Cache-Control', `public, immutable, max-age=31536000`)
+    },
+  })
+)
+```
+
 #### `onNotFound`
 
 The `onNotFound` is useful for debugging. You can write a handle for when a file is not found.

src/serve-static.ts

@@ -1,18 +1,19 @@
-import type { Context, MiddlewareHandler } from 'hono'
+import type { Context, Env, MiddlewareHandler } from 'hono'
 import { getFilePath, getFilePathWithoutDefaultDocument } from 'hono/utils/filepath'
 import { getMimeType } from 'hono/utils/mime'
 import { createReadStream, lstatSync } from 'fs'
 import type { ReadStream, Stats } from 'fs'
 
-export type ServeStaticOptions = {
+export type ServeStaticOptions<E extends Env = Env> = {
   /**
    * Root path, relative to current working directory from which the app was started. Absolute paths are not supported.
    */
   root?: string
   path?: string
   index?: string // default is 'index.html'
   rewriteRequestPath?: (path: string) => string
-  onNotFound?: (path: string, c: Context) => void | Promise<void>
+  onFound?: (path: string, c: Context<E>) => void | Promise<void>
+  onNotFound?: (path: string, c: Context<E>) => void | Promise<void>
 }
 
 const createStreamBody = (stream: ReadStream) => {
@@ -87,6 +88,7 @@ export const serveStatic = (options: ServeStaticOptions = { root: '' }): Middlew
       await options.onNotFound?.(path, c)
       return next()
     }
+    await options.onFound?.(path, c)
 
     const mimeType = getMimeType(path)
     if (mimeType) {

test/serve-static.test.ts

@@ -6,7 +6,15 @@ import { createAdaptorServer } from './../src/server'
 describe('Serve Static Middleware', () => {
   const app = new Hono()
 
-  app.use('/static/*', serveStatic({ root: './test/assets' }))
+  app.use(
+    '/static/*',
+    serveStatic({
+      root: './test/assets',
+      onFound: (path, c) => {
+        c.header('X-Custom', `Found the file at ${path}`)
+      },
+    })
+  )
   app.use('/favicon.ico', serveStatic({ path: './test/assets/favicon.ico' }))
   app.use(
     '/dot-static/*',
@@ -34,6 +42,7 @@ describe('Serve Static Middleware', () => {
     expect(res.status).toBe(200)
     expect(res.text).toBe('<h1>Hello Hono</h1>')
     expect(res.headers['content-type']).toBe('text/html; charset=utf-8')
+    expect(res.headers['x-custom']).toBe('Found the file at ./test/assets/static/index.html')
   })
 
   it('Should return hono.html', async () => {