Bind original request to onFile function this (#431)

* Bind `req` to `onFile` function `this`

* Type fix

* Readme change

* Use `call` instead of `bind`

Co-authored-by: Manuel Spigolon <behemoth89@gmail.com>

---------

Co-authored-by: Manuel Spigolon <behemoth89@gmail.com>

README.md

@@ -255,6 +255,8 @@ You can also define an `onFile` handler to avoid accumulating all files in memor
 
 ```js
 async function onFile(part) {
+  // you have access to original request via `this`
+  console.log(this.id)
   await pump(part.file, fs.createWriteStream(part.filename))
 }
 

index.d.ts

@@ -1,5 +1,5 @@
 import { Busboy, BusboyConfig, BusboyFileStream } from "@fastify/busboy";
-import { FastifyPluginCallback } from "fastify";
+import { FastifyPluginCallback, FastifyRequest } from "fastify";
 import { Readable } from "stream";
 import { FastifyErrorConstructor } from "@fastify/error";
 
@@ -200,7 +200,7 @@ declare namespace fastifyMultipart {
     /**
      * Manage the file stream like you need
      */
-    onFile?: (part: MultipartFile) => void | Promise<void>;
+    onFile?: (this: FastifyRequest, part: MultipartFile) => void | Promise<void>;
   }
 
   export const fastifyMultipart: FastifyMultipartPlugin;

index.js

@@ -157,7 +157,7 @@ function fastifyMultipart (fastify, options, done) {
         req.body = part.fields
         if (part.file) {
           if (options.onFile) {
-            await options.onFile(part)
+            await options.onFile.call(req, part)
           } else {
             await part.toBuffer()
           }

test/multipart-attach-body.test.js

@@ -171,7 +171,6 @@ test('should be able to attach all parsed field values and files with custom "on
 
   fastify.post('/', async function (req, reply) {
     t.ok(req.isMultipart())
-
     t.same(Object.keys(req.body), ['upload', 'hello'])
 
     t.equal(req.body.upload, original)
@@ -340,3 +339,51 @@ test('should manage array fields', async function (t) {
   await once(res, 'end')
   t.pass('res ended successfully')
 })
+
+test('should be able to attach all parsed field values and files with custom "onFile" handler with access to request object bind to "this"', async function (t) {
+  t.plan(6)
+
+  const fastify = Fastify()
+  t.teardown(fastify.close.bind(fastify))
+
+  async function onFile (part) {
+    t.pass('custom onFile handler')
+    t.equal(this.id, 'req-1')
+    t.equal(typeof this, 'object')
+    const buff = await part.toBuffer()
+    const decoded = Buffer.from(buff.toString(), 'base64').toString()
+    part.value = decoded
+  }
+
+  fastify.register(multipart, { attachFieldsToBody: 'keyValues', onFile })
+
+  const original = 'test upload content'
+
+  fastify.post('/', async function (req, reply) {
+    t.ok(req.isMultipart())
+    reply.code(200).send()
+  })
+
+  await fastify.listen({ port: 0 })
+
+  // request
+  const form = new FormData()
+  const opts = {
+    protocol: 'http:',
+    hostname: 'localhost',
+    port: fastify.server.address().port,
+    path: '/',
+    headers: form.getHeaders(),
+    method: 'POST'
+  }
+
+  const req = http.request(opts)
+  form.append('upload', Readable.from(Buffer.from(original).toString('base64')))
+  form.pipe(req)
+
+  const [res] = await once(req, 'response')
+  t.equal(res.statusCode, 200)
+  res.resume()
+  await once(res, 'end')
+  t.pass('res ended successfully')
+})