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Improve typescript types #390

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Sep 14, 2022
Merged

Improve typescript types #390

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2282c7b
improve typescript types
dwickern Sep 13, 2022
64e53b9
add undefined for missing fields
dwickern Sep 13, 2022
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32 changes: 22 additions & 10 deletions index.d.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -5,7 +5,7 @@ import { FastifyErrorConstructor } from "@fastify/error";

type MultipartHandler = (
field: string,
file: any,
file: BusboyFileStream,
filename: string,
encoding: string,
mimetype: string,
Expand All @@ -20,24 +20,36 @@ interface BodyEntry {
}

export interface MultipartFields {
[x: string]: Multipart | Multipart[];
[fieldname: string]: Multipart | Multipart[] | undefined;
}

export type Multipart<T = true> = T extends true ? MultipartFile : MultipartValue<T>;
export type Multipart = MultipartFile | MultipartValue;

export interface MultipartFile {
toBuffer: () => Promise<Buffer>,
file: BusboyFileStream,
filepath: string,
fieldname: string,
filename: string,
encoding: string,
mimetype: string,
fields: MultipartFields
}

export interface MultipartValue<T> {
value: T
export interface SavedMultipartFile extends MultipartFile {
/**
* Path to the temporary file
*/
filepath: string,
}

export interface MultipartValue<T = unknown> {
value: T;
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The value should be unknown, since it might be parsed as JSON based on the content-type provided by the caller. I've left it generic in case someone wants to assert its type.

fieldname: string;
mimetype?: string;
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string | undefined because mime type get swallowed when we parse the value as JSON. I think this is a bug, but that's for another PR.

encoding: string;
fieldnameTruncated: boolean;
valueTruncated: boolean;
fields: MultipartFields;
}

interface MultipartErrors {
Expand All @@ -60,13 +72,13 @@ declare module "fastify" {
multipart: (handler: MultipartHandler, next: (err: Error) => void, options?: Omit<BusboyConfig, 'headers'>) => Busboy;

// Stream mode
file: (options?: Omit<BusboyConfig, 'headers'>) => Promise<Multipart>
files: (options?: Omit<BusboyConfig, 'headers'>) => AsyncIterableIterator<Multipart>
file: (options?: Omit<BusboyConfig, 'headers'>) => Promise<MultipartFile | undefined>
files: (options?: Omit<BusboyConfig, 'headers'>) => AsyncIterableIterator<MultipartFile>

// Disk mode
saveRequestFiles: (options?: Omit<BusboyConfig, 'headers'> & { tmpdir?: string }) => Promise<Array<Multipart>>
saveRequestFiles: (options?: Omit<BusboyConfig, 'headers'> & { tmpdir?: string }) => Promise<Array<SavedMultipartFile>>
cleanRequestFiles: () => Promise<void>
tmpUploads: Array<Multipart>
tmpUploads: Array<string> | null
}

interface FastifyInstance {
Expand Down
29 changes: 22 additions & 7 deletions test/index.test-d.ts
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Original file line number Diff line number Diff line change
@@ -1,8 +1,7 @@
import fastify from 'fastify'
import fastifyMultipart from '..'
import { Multipart, MultipartFields, MultipartFile } from '..'
import fastifyMultipart, {MultipartValue, MultipartFields, MultipartFile } from '..'
import * as util from 'util'
import { pipeline, Readable } from 'stream'
import { pipeline } from 'stream'
import * as fs from 'fs'
import { expectError, expectType } from 'tsd'
import { FastifyErrorConstructor } from "@fastify/error"
Expand Down Expand Up @@ -55,6 +54,7 @@ const runServer = async () => {
// usage
app.post('/', async (req, reply) => {
const data = await req.file()
if (data == null) throw new Error('missing file')

expectType<BusboyFileStream>(data.file)
expectType<boolean>(data.file.truncated)
Expand All @@ -63,14 +63,27 @@ const runServer = async () => {
expectType<string>(data.filename)
expectType<string>(data.encoding)
expectType<string>(data.mimetype)

const field = data.fields.myField;
if (field === undefined) {
// field missing from the request
} else if (Array.isArray(field)) {
// multiple fields with the same name
} else if ('file' in field) {
// field containing a file
field.file.resume()
} else {
// field containing a value
field.fields.value;
}

await pump(data.file, fs.createWriteStream(data.filename))

reply.send()
})

// Multiple fields including scalar values
app.post<{Body: {file: Multipart, foo: Multipart<string>}}>('/upload/stringvalue', async (req, reply) => {
app.post<{Body: {file: MultipartFile, foo: MultipartValue<string>}}>('/upload/stringvalue', async (req, reply) => {
expectError(req.body.foo.file);
expectType<string>(req.body.foo.value);

Expand All @@ -79,7 +92,7 @@ const runServer = async () => {
reply.send();
})

app.post<{Body: {file: Multipart, num: Multipart<number>}}>('/upload/stringvalue', async (req, reply) => {
app.post<{Body: {file: MultipartFile, num: MultipartValue<number>}}>('/upload/stringvalue', async (req, reply) => {
expectType<number>(req.body.num.value);
reply.send();

Expand All @@ -92,6 +105,7 @@ const runServer = async () => {
app.post('/', async function (req, reply) {
const options: Partial<BusboyConfig> = { limits: { fileSize: 1000 } };
const data = await req.file(options)
if (!data) throw new Error('missing file')
await pump(data.file, fs.createWriteStream(data.filename))
reply.send()
})
Expand All @@ -109,10 +123,10 @@ const runServer = async () => {
app.post('/upload/raw/any', async function (req, reply) {
const parts = req.parts()
for await (const part of parts) {
if (part.file) {
if ('file' in part) {
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This should be modified on README as well. But this needs to be revisited to be on the type.

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Your problem is TypeScript issue.
TypeScript cannot restrict the type in certain format that's the cause.

The README example is certainly valid in Javascript.

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Yes, typescript wants you to use in for narrowing in this situation, which works for both JS and TS.
https://www.typescriptlang.org/docs/handbook/2/narrowing.html#the-in-operator-narrowing

A discriminator would perhaps be ideal:

export interface MultipartFile {
  type: 'file',
  ...
}
export interface MultipartValue<T = unknown> {
  type: 'value',
  ...
}

if (part.type === 'file') {
  part.toBuffer()
}

await pump(part.file, fs.createWriteStream(part.filename))
} else {
console.log(part)
console.log(part.value)
}
}
reply.send()
Expand All @@ -121,6 +135,7 @@ const runServer = async () => {
// accumulate whole file in memory
app.post('/upload/raw/any', async function (req, reply) {
const data = await req.file()
if (!data) throw new Error('missing file')
const buffer = await data.toBuffer()
// upload to S3
reply.send()
Expand Down