feat: part.type for easy type narrowing

README.md

@@ -147,9 +147,10 @@ fastify.post('/', async function (req, reply) {
 fastify.post('/upload/raw/any', async function (req, reply) {
   const parts = req.parts()
   for await (const part of parts) {
-    if (part.file) {
+    if (part.type === 'file') {
       await pump(part.file, fs.createWriteStream(part.filename))
     } else {
+      // part.type === 'field
       console.log(part)
     }
   }
@@ -177,6 +178,7 @@ This will store all files in the operating system default directory for temporar
 fastify.post('/upload/files', async function (req, reply) {
   // stores files to tmp dir and return files
   const files = await req.saveRequestFiles()
+  files[0].type // "file"
   files[0].filepath
   files[0].fieldname
   files[0].filename

examples/example.js

@@ -41,9 +41,10 @@ fastify.post('/upload/stream/files', async function (req, reply) {
 fastify.post('/upload/raw/any', async function (req, reply) {
   const parts = req.parts()
   for await (const part of parts) {
-    if (part.file) {
+    if (part.type === 'file') {
       await pump(part.file, fs.createWriteStream(part.filename))
     } else {
+      // part.type === 'field'
       console.log(part)
     }
   }

index.d.ts

@@ -82,6 +82,7 @@ declare namespace fastifyMultipart {
   export type Multipart = MultipartFile | MultipartValue;
 
   export interface MultipartFile {
+    type: 'file';
     toBuffer: () => Promise<Buffer>;
     file: BusboyFileStream;
     fieldname: string;
@@ -92,6 +93,7 @@ declare namespace fastifyMultipart {
   }
 
   export interface MultipartValue<T = unknown> {
+    type: 'field';
     value: T;
     fieldname: string;
     mimetype: string;

index.js

@@ -410,6 +410,7 @@ function fastifyMultipart (fastify, options, done) {
       }
 
       const value = {
+        type: 'field',
         fieldname: name,
         mimetype: contentType,
         encoding,
@@ -444,6 +445,7 @@ function fastifyMultipart (fastify, options, done) {
         : defaultThrowFileSizeLimit
 
       const value = {
+        type: 'file',
         fieldname: name,
         filename,
         encoding,

test/big.test.js

@@ -13,7 +13,7 @@ const sendToWormhole = require('stream-wormhole')
 
 // skipping on Github Actions because it takes too long
 test('should upload a big file in constant memory', { skip: process.env.CI }, function (t) {
-  t.plan(9)
+  t.plan(10)
 
   const fastify = Fastify()
   const hashInput = crypto.createHash('sha256')
@@ -32,6 +32,7 @@ test('should upload a big file in constant memory', { skip: process.env.CI }, fu
 
     for await (const part of req.parts()) {
       if (part.file) {
+        t.equal(part.type, 'file')
         t.equal(part.fieldname, 'upload')
         t.equal(part.filename, 'random-data')
         t.equal(part.encoding, '7bit')

test/fix-313.test.js

@@ -14,7 +14,7 @@ const { once } = EventEmitter
 const filePath = path.join(__dirname, '../README.md')
 
 test('should store file on disk, remove on response when attach fields to body is true', async function (t) {
-  t.plan(22)
+  t.plan(25)
 
   const fastify = Fastify()
   t.teardown(fastify.close.bind(fastify))
@@ -29,18 +29,21 @@ test('should store file on disk, remove on response when attach fields to body i
     const files = await req.saveRequestFiles()
 
     t.ok(files[0].filepath)
+    t.equal(files[0].type, 'file')
     t.equal(files[0].fieldname, 'upload')
     t.equal(files[0].filename, 'README.md')
     t.equal(files[0].encoding, '7bit')
     t.equal(files[0].mimetype, 'text/markdown')
     t.ok(files[0].fields.upload)
     t.ok(files[1].filepath)
+    t.equal(files[1].type, 'file')
     t.equal(files[1].fieldname, 'upload')
     t.equal(files[1].filename, 'README.md')
     t.equal(files[1].encoding, '7bit')
     t.equal(files[1].mimetype, 'text/markdown')
     t.ok(files[1].fields.upload)
     t.ok(files[2].filepath)
+    t.equal(files[2].type, 'file')
     t.equal(files[2].fieldname, 'other')
     t.equal(files[2].filename, 'README.md')
     t.equal(files[2].encoding, '7bit')

test/index.test-d.ts

@@ -3,7 +3,7 @@ import fastifyMultipart, {MultipartValue, MultipartFields, MultipartFile } from
 import * as util from 'util'
 import { pipeline } from 'stream'
 import * as fs from 'fs'
-import { expectError, expectType } from 'tsd'
+import { expectError, expectType, expectAssignable } from 'tsd'
 import { FastifyErrorConstructor } from "@fastify/error"
 import { BusboyConfig, BusboyFileStream } from "@fastify/busboy";
 
@@ -55,7 +55,8 @@ const runServer = async () => {
   app.post('/', async (req, reply) => {
     const data = await req.file()
     if (data == null) throw new Error('missing file')
-
+
+    expectAssignable<string>(data.type)
     expectType<BusboyFileStream>(data.file)
     expectType<boolean>(data.file.truncated)
     expectType<MultipartFields>(data.fields)
@@ -69,7 +70,7 @@ const runServer = async () => {
       // field missing from the request
     } else if (Array.isArray(field)) {
       // multiple fields with the same name
-    } else if ('file' in field) {
+    } else if (field.type === 'file') {
       // field containing a file
       field.file.resume()
     } else {
@@ -88,7 +89,7 @@ const runServer = async () => {
     expectType<string>(req.body.foo.value);
 
     expectType<BusboyFileStream>(req.body.file.file)
-    expectError(req.body.file.value);
+    expectAssignable<string>(req.body.file.type);
     reply.send();
   })
 
@@ -123,7 +124,7 @@ const runServer = async () => {
   app.post('/upload/raw/any', async function (req, reply) {
     const parts = req.parts()
     for await (const part of parts) {
-      if ('file' in part) {
+      if (part.type === 'file') {
         await pump(part.file, fs.createWriteStream(part.filename))
       } else {
         console.log(part.value)
@@ -145,6 +146,7 @@ const runServer = async () => {
   app.post('/upload/files', async function (req, reply) {
     // stores files to tmp dir and return files
     const files = await req.saveRequestFiles()
+    files[0].type // "file"
     files[0].filepath
     files[0].fieldname
     files[0].filename

test/multipart-body-schema.test.js

@@ -11,7 +11,7 @@ const fs = require('fs')
 const filePath = path.join(__dirname, '../README.md')
 
 test('should be able to use JSON schema to validate request', function (t) {
-  t.plan(6)
+  t.plan(7)
 
   const fastify = Fastify()
   t.teardown(fastify.close.bind(fastify))
@@ -39,6 +39,7 @@ test('should be able to use JSON schema to validate request', function (t) {
     const content = await req.body.upload.toBuffer()
 
     t.equal(content.toString(), original)
+    t.equal(req.body.hello.type, 'field')
     t.equal(req.body.hello.value, 'world')
 
     reply.code(200).send()

test/multipart.test.js

@@ -17,7 +17,7 @@ const sendToWormhole = require('stream-wormhole')
 const filePath = path.join(__dirname, '../README.md')
 
 test('should parse forms', function (t) {
-  t.plan(8)
+  t.plan(9)
 
   const fastify = Fastify()
   t.teardown(fastify.close.bind(fastify))
@@ -27,6 +27,7 @@ test('should parse forms', function (t) {
   fastify.post('/', async function (req, reply) {
     for await (const part of req.parts()) {
       if (part.file) {
+        t.equal(part.type, 'file')
         t.equal(part.fieldname, 'upload')
         t.equal(part.filename, 'README.md')
         t.equal(part.encoding, '7bit')
@@ -76,7 +77,7 @@ test('should parse forms', function (t) {
 })
 
 test('should respond when all files are processed', function (t) {
-  t.plan(4)
+  t.plan(6)
 
   const fastify = Fastify()
   t.teardown(fastify.close.bind(fastify))
@@ -87,6 +88,7 @@ test('should respond when all files are processed', function (t) {
     const parts = req.files()
     for await (const part of parts) {
       t.ok(part.file)
+      t.equal(part.type, 'file')
       await sendToWormhole(part.file)
     }
     reply.code(200).send()
@@ -327,6 +329,7 @@ test('should be able to configure limits globally with plugin register options',
       const parts = req.files()
       for await (const part of parts) {
         t.ok(part.file)
+        t.equal(part.type, 'file')
         await sendToWormhole(part.file)
       }
       reply.code(200).send()
@@ -469,7 +472,7 @@ test('should throw error due to partsLimit (The max number of parts (fields + fi
 })
 
 test('should throw error due to file size limit exceed (Default: true)', function (t) {
-  t.plan(4)
+  t.plan(6)
 
   const fastify = Fastify()
   t.teardown(fastify.close.bind(fastify))
@@ -481,6 +484,7 @@ test('should throw error due to file size limit exceed (Default: true)', functio
       const parts = req.files()
       for await (const part of parts) {
         t.ok(part.file)
+        t.equal(part.type, 'file')
         await sendToWormhole(part.file)
       }
       reply.code(200).send()
@@ -516,7 +520,7 @@ test('should throw error due to file size limit exceed (Default: true)', functio
 })
 
 test('should not throw error due to file size limit exceed - files setting (Default: true)', function (t) {
-  t.plan(3)
+  t.plan(5)
 
   const fastify = Fastify()
   t.teardown(fastify.close.bind(fastify))
@@ -527,6 +531,7 @@ test('should not throw error due to file size limit exceed - files setting (Defa
     const parts = req.files({ limits: { fileSize: 1 } })
     for await (const part of parts) {
       t.ok(part.file)
+      t.equal(part.type, 'file')
       await sendToWormhole(part.file)
     }
     reply.code(200).send()
@@ -557,7 +562,7 @@ test('should not throw error due to file size limit exceed - files setting (Defa
 })
 
 test('should not miss fields if part handler takes much time than formdata parsing', async function (t) {
-  t.plan(11)
+  t.plan(12)
 
   const original = fs.readFileSync(filePath, 'utf8')
   const immediate = util.promisify(setImmediate)
@@ -576,6 +581,7 @@ test('should not miss fields if part handler takes much time than formdata parsi
 
     for await (const part of req.parts()) {
       if (part.file) {
+        t.equal(part.type, 'file')
         t.equal(part.fieldname, 'upload')
         t.equal(part.filename, 'README.md')
         t.equal(part.encoding, '7bit')