then-busboy
Advanced tools
Promise-based wrapper around Busboy. Processes multipart/form-data content and returns it as a single object.
Promise-based wrapper around Busboy. Processes multipart/form-data content and returns it as a single object.
You can install then-busboy from npm:
npm install --save then-busboy
Or with yarn:
yarn add then-busboy
then-busboy works fine even with a pure Node.js HTTP server. Let's take a look to the tiny example:
import parse from "then-busboy"
import {createServer} from "http"
function handler(req, res) {
// Get result from then-busboy
function onFulfilled(body) {
res.writeHead("Content-Type", "application/json")
// You can also do something with each file and a field.
res.end(JSON.stringify(body.json()))
}
// Handle errors
function onRejected(err) {
res.statusCode = err.status || 500
res.end(String(err))
}
// Call `then-busboy` with `req`
parse(req).then(onFulfilled, onRejected)
}
createServer(handler)
.listen(2319, () => console.log("Server started on http://localhost:2319"))
Note: You can use asynchronous function syntax, because then-busboy always returns a Promise.
So, let's see on a simple middleware example for Koa.js:
import {promises as fs} from "fs"
import {parse} from "then-busboy"
const toLowerCase = string => String.prototype.toLowerCase.call(string)
const unlinkFile = ({path}) => fs.unlink(path)
async function multipart(ctx, next) {
if (["post", "put"].includes(toLowerCase(ctx.method)) === false) {
return next()
}
if (ctx.is("multipart/form-data") === false) {
return next()
}
const body = await parse(ctx.req)
ctx.request.body = body.json()
await next()
// Cleanup files
return Promise.all(Array.from(body.files().values()).map(unlinkFile))
.catch(err => err.code !== "ENOENT" && Promise.reject(err))
}
export default multipart
Breaking change: Since 4.x version then-busboy returns a Body object instead of raw data. For more information check out the Usage section of documentation and take a look at Body class in API section.
parse(request[, options]) -> {Promise<Body>}constructor Body(entries)Create an object that allows to manipulate FormData fields taken then-busboy
isBody(value) -> {boolean}Check if given value is instance of Body
from(entries) -> {Body}Create a new Body from given entries. An alias of new Body(entries)
then-busboyjson(value) -> {object}Return an object with data taken from given entries or Body
formData(value) -> {FormData}Return a FormData instance with data taken from given entries or Body
get length() -> {number}Return an amount of entries and files in current Body instance
get fields() -> {Body}Return a new Body that contains fields only
get files() -> {Body}Return a new Body that contains files only
json() -> {object}Return an object with data taken the current Body instance
formData() -> {FormData}Return a FormData with data taken the current Body instance
map(callback[, ctx]) -> {Body}Create a new Body with the results of calling a provided function on every entry in the calling Body
filter(predicate[, ctx]) -> {Body}Create a new Body with all entries that pass the test implemented in given function
true to keep the entry, false otherwise. It accepts four arguments:
forEach(callback[, ctx]) -> {Body}Execute a given callback for each entry of the Body instance
entries() -> {Array<[string[], any]>}Return an array of entries in current Body instance
values() -> {Iterator}Return an iterator allows to go through the Body values
names() -> {Iterator}Return an iterator allows to go through the Body fields name
paths() -> {Iterator}Return an iterator allows to go through the Body fields path
constructor File(options)isFile(value) -> {boolean}Check if given value is a File instance.
contentsFile contents Readable stream.
streamAlias for File#contents
filenameFull name of the file
basenameName of the file without extension
extnameFile extension
mimeFile mime type
encFile contents encoding
pathDefault path of the file
read() => {Promise<Buffer>}Read a file from contents stream.
write([path]) => {Promise<void>}Write a file content to disk. Optionally you can set a custom path.
By default, file will be saved in system temporary directory os.tmpdir().
You can take this path from path property.
then-busboy can restore an object structure from form-data field names if you will follow the naming formats with dots or square brackets:
This notation looks similarly to JS object properties accessiong syntax:
# Flat objects looks the same in both notations
# Note that the following notation examples is just a pseudo code
name = "John Doe"
age = 25
then-busboy will return the this object for an example from above:
{
name: "John Doe",
// By default, non-string values will be converted to their initial type.
// So, "25" -> 25, "null" -> null, "false" -> false etc.
age: 25
}
For deep objects or collections, use dot or brackets as a separator. But don't mix them.
rootField.nestedField = "Some text here"
{
rootField: {
nestedField: "Some text here"
}
}
rootField[nestedField] = "I beat Twilight Sparkle and all I got was this lousy t-shirt"
Becomes
{
rootField: {
nestedField: "I beat Twilight Sparkle and all I got was this lousy t-shirt"
}
}
You can also send an arrays and collections using bracket format:
message[sender] = "John Doe"
message[text] = "Some whatever text message."
message[attachments][0][file] = <here is the file content>
message[attachments][0][description] = "Here is a description of the file"
then-busboy returns the following object:
{
message: {
sender: "John Doe",
text: "Some whatever text message.",
attachments: [
{
"file": File, // this field will be represended as a File instance
"description": "Here is a description of the file"
}
]
}
}
Collections allowed too:
[0][firstName] = "John"
[0][lastName] = "Doe"
[0][dob][day] = "1"
[0][dob][month] = "Jan."
[0][dob][year] = "1989"
[0][skills][0] = "Node.js"
[0][skills][1] = "CoffeeScript"
[0][skills][2] = "JavaScript"
[0][skills][3] = "Babel"
[1][firstName] = "Max"
[1][lastName] = "Doe"
[1][dob][day] = "12"
[1][dob][month] = "Mar."
[1][dob][year] = "1992"
[1][skills][0] = "Python"
[1][skills][1] = "Flask"
[1][skills][2] = "JavaScript"
[1][skills][3] = "Babel"
[1][skills][4] = "React"
[1][skills][5] = "Redux"
Then you will receive:
[
{
firstName: "John",
lastName: "Doe",
dob: {
day: 1,
month: "Jan.",
year: 1989
},
skills: ["Node.js", "CoffeeScript", "JavaScript", "Babel"]
}, {
firstName: "Max",
lastName: "Doe",
dob: {
day: 12,
month: "Mar.",
year: 1992
},
skills: ["Python", "Flask", "JavaScript", "Babel", "React", "Redux"]
}
]
On limits (if some of them set) then-busboy will throw an error,
there are exposed classes that you can use to handle each kind of limit errors:
FAQs
Promise-based wrapper around Busboy. Processes multipart/form-data request body and returns it in a single object.
We found that then-busboy demonstrated a not healthy version release cadence and project activity because the last version was released a year ago. It has 1 open source maintainer collaborating on the project.
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