feat: add option to disable automatic 304 responses (#117)

* feat: add option to disable automatic 304 responses * Apply suggestions from code review * Update index.js --------- Co-authored-by: Aras Abbasi <[email protected]>
fastify · Nov 29, 2023 · f3ddf3d · f3ddf3d
1 parent f1ec3fc
commit f3ddf3d
Show file tree

Hide file tree

Showing 4 changed files with 28 additions and 5 deletions.
diff --git a/README.md b/README.md
@@ -4,8 +4,9 @@
 [![NPM version](https://img.shields.io/npm/v/@fastify/etag.svg?style=flat)](https://www.npmjs.com/package/@fastify/etag)
 [![js-standard-style](https://img.shields.io/badge/code%20style-standard-brightgreen.svg?style=flat)](https://standardjs.com/)
 
-A plugin for [Fastify](https://www.fastify.io) that automatically generates HTTP ETags and returns 304 when needed,
-according to [RFC2616-sec13](https://www.w3.org/Protocols/rfc2616/rfc2616-sec13.html).
+A plugin for [Fastify](https://www.fastify.io) that automatically generates HTTP ETags according to [RFC2616-sec13](https://www.w3.org/Protocols/rfc2616/rfc2616-sec13.html).
+
+The plugin can optionally send a 304 status code when an ETag matches the if-none-match header.
 
 
 ## Install
@@ -45,6 +46,12 @@ app.listen(3000)
 
 * `weak`: generates weak ETags by default. Default: `false`.
 
+### Automatic 304 status codes
+
+By default, the plugin sends a 304 status code when the ETag is equal to the Etag specified by the if-none-match request header.
+
+This is often the desired behaviour, but can be disabled by setting `replyWith304: false`.
+
 ## Acknowledgements
 
 The fnv1a logic was forked from https://github.com/sindresorhus/fnv1a and adapted to support buffers.

diff --git a/index.js b/index.js
@@ -29,8 +29,8 @@ function buildHashFn (algorithm = 'sha1', weak = false) {
     .update(payload).digest('base64') + '"'
 }
 
-async function fastifyEtag (app, opts) {
-  const hash = buildHashFn(opts.algorithm, opts.weak)
+async function fastifyEtag (app, { algorithm, weak, replyWith304 = true }) {
+  const hash = buildHashFn(algorithm, weak)
 
   app.addHook('onSend', function (req, reply, payload, done) {
     let etag = reply.getHeader('etag')
@@ -48,7 +48,7 @@ async function fastifyEtag (app, opts) {
       reply.header('etag', etag)
     }
 
-    if (req.headers['if-none-match'] === etag) {
+    if (replyWith304 && req.headers['if-none-match'] === etag) {
       reply.code(304)
       newPayload = ''
     }

diff --git a/test/generic.js b/test/generic.js
@@ -54,6 +54,21 @@ module.exports = function ({ test }, etagOpts, hashFn) {
     })
   })
 
+  test('does not return a 304 when behaviour is disabled', async (t) => {
+    const res = await build({ replyWith304: false }).inject({
+      url: '/',
+      headers: {
+        'If-None-Match': hash
+      }
+    })
+
+    t.same(JSON.parse(res.body), { hello: 'world' })
+    t.equal(res.statusCode, 200)
+    t.match(res.headers, {
+      etag: hash
+    })
+  })
+
   test('returns an already existing etag', async (t) => {
     const res = await build().inject({
       url: '/etag'

diff --git a/types/index.d.ts b/types/index.d.ts
@@ -6,6 +6,7 @@ declare namespace fastifyEtag {
   export interface FastifyEtagOptions {
     algorithm?: 'fnv1a' | string;
     weak?: boolean;
+    replyWith304?: boolean;
   }
 
   export const fastifyEtag: FastifyEtag