# body-parser

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Node.js body parsing middleware.

Parse incoming request bodies in a middleware before your handlers, available
under the `req.body` property.

**Note** As `req.body`'s shape is based on user-controlled input, all
properties and values in this object are untrusted and should be validated
before trusting. For example, `req.body.foo.toString()` may fail in multiple
ways, for example the `foo` property may not be there or may not be a string,
and `toString` may not be a function and instead a string or other user input.

[Learn about the anatomy of an HTTP transaction in Node.js](https://nodejs.org/en/learn/http/anatomy-of-an-http-transaction).

_This does not handle multipart bodies_, due to their complex and typically
large nature. For multipart bodies, you may be interested in the following
modules:

  * [busboy](https://www.npmjs.com/package/busboy#readme) and
    [connect-busboy](https://www.npmjs.com/package/connect-busboy#readme)
  * [multiparty](https://www.npmjs.com/package/multiparty#readme) and
    [connect-multiparty](https://www.npmjs.com/package/connect-multiparty#readme)
  * [formidable](https://www.npmjs.com/package/formidable#readme)
  * [multer](https://www.npmjs.com/package/multer#readme)

This module provides the following parsers:

  * [JSON body parser](#bodyparserjsonoptions)
  * [Raw body parser](#bodyparserrawoptions)
  * [Text body parser](#bodyparsertextoptions)
  * [URL-encoded form body parser](#bodyparserurlencodedoptions)

Other body parsers you might be interested in:

- [body](https://www.npmjs.com/package/body#readme)
- [co-body](https://www.npmjs.com/package/co-body#readme)

## Installation

```sh
$ npm install body-parser
```

## API

```js
// Import all parsers
const bodyParser = require('body-parser')

// Or import individual parsers directly
const json = require('body-parser/json')
const urlencoded = require('body-parser/urlencoded')
const raw = require('body-parser/raw')
const text = require('body-parser/text')
```

The `bodyParser` object exposes various factories to create middlewares. All
middlewares will populate the `req.body` property with the parsed body when
the `Content-Type` request header matches the `type` option.

The various errors returned by this module are described in the
[errors section](#errors).

### bodyParser.json([options])

Returns middleware that only parses `json` and only looks at requests where
the `Content-Type` header matches the `type` option. This parser accepts any
Unicode encoding of the body and supports automatic inflation of `gzip`,
`br` (brotli) and `deflate` encodings.

A new `body` object containing the parsed data is populated on the `request`
object after the middleware (i.e. `req.body`).

#### Options

The `json` function takes an optional `options` object that may contain any of
the following keys:

##### defaultCharset

Specify the default character set for the json content if the charset is not
specified in the `Content-Type` header of the request. Defaults to `utf-8`.

##### inflate

When set to `true`, then deflated (compressed) bodies will be inflated; when
`false`, deflated bodies are rejected. Defaults to `true`.

##### limit

Controls the maximum request body size. If this is a number, then the value
specifies the number of bytes; if it is a string, the value is passed to the
[bytes](https://www.npmjs.com/package/bytes) library for parsing. Defaults
to `'100kb'`.

> It’s recommended not to configure a very high limit and to use the default value whenever possible. Allowing larger payloads increases memory usage because of the resources required for decoding and transformations, and it can also lead to longer response times as more data is processed. By ‘very high’, we mean values above the default, for example payloads of 5 MB or more can already start to introduce these risks. With the default limits, these issues do not occur.

##### reviver

The `reviver` option is passed directly to `JSON.parse` as the second
argument. You can find more information on this argument
[in the MDN documentation about JSON.parse](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/JSON/parse#the_reviver_parameter).

##### strict

When set to `true`, will only accept arrays and objects; when `false` will
accept anything `JSON.parse` accepts. Defaults to `true`.

##### type

The `type` option is used to determine what media type the middleware will
parse. This option can be a string, array of strings, or a function. If not a
function, `type` option is passed directly to the
[type-is](https://www.npmjs.com/package/type-is#readme) library and this can
be an extension name (like `json`), a mime type (like `application/json`), or
a mime type with a wildcard (like `*/*` or `*/json`). If a function, the `type`
option is called as `fn(req)` and the request is parsed if it returns a truthy
value. Defaults to `application/json`.

##### verify

The `verify` option, if supplied, is called as `verify(req, res, buf, encoding)`,
where `buf` is a `Buffer` of the raw request body and `encoding` is the
encoding of the request. The parsing can be aborted by throwing an error.

### bodyParser.raw([options])

Returns middleware that parses all bodies as a `Buffer` and only looks at
requests where the `Content-Type` header matches the `type` option. This
parser supports automatic inflation of `gzip`, `br` (brotli) and `deflate`
encodings.

A new `body` object containing the parsed data is populated on the `request`
object after the middleware (i.e. `req.body`). This will be a `Buffer` object
of the body.

#### Options

The `raw` function takes an optional `options` object that may contain any of
the following keys:

##### inflate

When set to `true`, then deflated (compressed) bodies will be inflated; when
`false`, deflated bodies are rejected. Defaults to `true`.

##### limit

Controls the maximum request body size. If this is a number, then the value
specifies the number of bytes; if it is a string, the value is passed to the
[bytes](https://www.npmjs.com/package/bytes) library for parsing. Defaults
to `'100kb'`.

> It’s recommended not to configure a very high limit and to use the default value whenever possible. Allowing larger payloads increases memory usage because of the resources required for decoding and transformations, and it can also lead to longer response times as more data is processed. By ‘very high’, we mean values above the default, for example payloads of 5 MB or more can already start to introduce these risks. With the default limits, these issues do not occur.

##### type

The `type` option is used to determine what media type the middleware will
parse. This option can be a string, array of strings, or a function.
If not a function, `type` option is passed directly to the
[type-is](https://www.npmjs.com/package/type-is#readme) library and this
can be an extension name (like `bin`), a mime type (like
`application/octet-stream`), or a mime type with a wildcard (like `*/*` or
`application/*`). If a function, the `type` option is called as `fn(req)`
and the request is parsed if it returns a truthy value. Defaults to
`application/octet-stream`.

##### verify

The `verify` option, if supplied, is called as `verify(req, res, buf, encoding)`,
where `buf` is a `Buffer` of the raw request body and `encoding` is the
encoding of the request. The parsing can be aborted by throwing an error.

### bodyParser.text([options])

Returns middleware that parses all bodies as a string and only looks at
requests where the `Content-Type` header matches the `type` option. This
parser supports automatic inflation of `gzip`, `br` (brotli) and `deflate`
encodings.

A new `body` string containing the parsed data is populated on the `request`
object after the middleware (i.e. `req.body`). This will be a string of the
body.

#### Options

The `text` function takes an optional `options` object that may contain any of
the following keys:

##### defaultCharset

Specify the default character set for the text content if the charset is not
specified in the `Content-Type` header of the request. Defaults to `utf-8`.

##### inflate

When set to `true`, then deflated (compressed) bodies will be inflated; when
`false`, deflated bodies are rejected. Defaults to `true`.

##### limit

Controls the maximum request body size. If this is a number, then the value
specifies the number of bytes; if it is a string, the value is passed to the
[bytes](https://www.npmjs.com/package/bytes) library for parsing. Defaults
to `'100kb'`.

> It’s recommended not to configure a very high limit and to use the default value whenever possible. Allowing larger payloads increases memory usage because of the resources required for decoding and transformations, and it can also lead to longer response times as more data is processed. By ‘very high’, we mean values above the default, for example payloads of 5 MB or more can already start to introduce these risks. With the default limits, these issues do not occur.

##### type

The `type` option is used to determine what media type the middleware will
parse. This option can be a string, array of strings, or a function. If not
a function, `type` option is passed directly to the
[type-is](https://www.npmjs.com/package/type-is#readme) library and this can
be an extension name (like `txt`), a mime type (like `text/plain`), or a mime
type with a wildcard (like `*/*` or `text/*`). If a function, the `type`
option is called as `fn(req)` and the request is parsed if it returns a
truthy value. Defaults to `text/plain`.

##### verify

The `verify` option, if supplied, is called as `verify(req, res, buf, encoding)`,
where `buf` is a `Buffer` of the raw request body and `encoding` is the
encoding of the request. The parsing can be aborted by throwing an error.

### bodyParser.urlencoded([options])

Returns middleware that only parses `urlencoded` bodies and only looks at
requests where the `Content-Type` header matches the `type` option. This
parser accepts only UTF-8 and ISO-8859-1 encodings of the body and supports 
automatic inflation of `gzip`, `br` (brotli) and `deflate` encodings.

A new `body` object containing the parsed data is populated on the `request`
object after the middleware (i.e. `req.body`). This object will contain
key-value pairs, where the value can be a string or array (when `extended` is
`false`), or any type (when `extended` is `true`).

#### Options

The `urlencoded` function takes an optional `options` object that may contain
any of the following keys:

##### extended

The "extended" syntax allows for rich objects and arrays to be encoded into the
URL-encoded format, allowing for a JSON-like experience with URL-encoded. For
more information, please [see the qs
library](https://www.npmjs.com/package/qs#readme).

Defaults to `false`.

##### inflate

When set to `true`, then deflated (compressed) bodies will be inflated; when
`false`, deflated bodies are rejected. Defaults to `true`.

##### limit

Controls the maximum request body size. If this is a number, then the value
specifies the number of bytes; if it is a string, the value is passed to the
[bytes](https://www.npmjs.com/package/bytes) library for parsing. Defaults
to `'100kb'`.

> It’s recommended not to configure a very high limit and to use the default value whenever possible. Allowing larger payloads increases memory usage because of the resources required for decoding and transformations, and it can also lead to longer response times as more data is processed. By ‘very high’, we mean values above the default, for example payloads of 5 MB or more can already start to introduce these risks. With the default limits, these issues do not occur.

##### parameterLimit

The `parameterLimit` option controls the maximum number of parameters that
are allowed in the URL-encoded data. If a request contains more parameters
than this value, a 413 will be returned to the client. Defaults to `1000`.

##### type

The `type` option is used to determine what media type the middleware will
parse. This option can be a string, array of strings, or a function. If not
a function, `type` option is passed directly to the
[type-is](https://www.npmjs.com/package/type-is#readme) library and this can
be an extension name (like `urlencoded`), a mime type (like
`application/x-www-form-urlencoded`), or a mime type with a wildcard (like
`*/x-www-form-urlencoded`). If a function, the `type` option is called as
`fn(req)` and the request is parsed if it returns a truthy value. Defaults
to `application/x-www-form-urlencoded`.

##### verify

The `verify` option, if supplied, is called as `verify(req, res, buf, encoding)`,
where `buf` is a `Buffer` of the raw request body and `encoding` is the
encoding of the request. The parsing can be aborted by throwing an error.

##### defaultCharset

The default charset to parse as, if not specified in content-type. Must be
either `utf-8` or `iso-8859-1`. Defaults to `utf-8`.

##### charsetSentinel

Whether to let the value of the `utf8` parameter take precedence as the charset
selector. It requires the form to contain a parameter named `utf8` with a value
of `✓`. Defaults to `false`.

##### interpretNumericEntities

Whether to decode numeric entities such as `&#9786;` when parsing an iso-8859-1
form. Defaults to `false`.


##### depth

The `depth` option is used to configure the maximum depth of the `qs` library when `extended` is `true`. This allows you to limit the amount of keys that are parsed and can be useful to prevent certain types of abuse. Defaults to `32`. It is recommended to keep this value as low as possible.

## Errors

The middlewares provided by this module create errors using the
[`http-errors` module](https://www.npmjs.com/package/http-errors). The errors
will typically have a `status`/`statusCode` property that contains the suggested
HTTP response code, an `expose` property to determine if the `message` property
should be displayed to the client, a `type` property to determine the type of
error without matching against the `message`, and a `body` property containing
the read body, if available.

The following are the common errors created, though any error can come through
for various reasons.

### content encoding unsupported

This error will occur when the request had a `Content-Encoding` header that
contained an encoding but the "inflation" option was set to `false`. The
`status` property is set to `415`, the `type` property is set to
`'encoding.unsupported'`, and the `charset` property will be set to the
encoding that is unsupported.

### entity parse failed

This error will occur when the request contained an entity that could not be
parsed by the middleware. The `status` property is set to `400`, the `type`
property is set to `'entity.parse.failed'`, and the `body` property is set to
the entity value that failed parsing.

### entity verify failed

This error will occur when the request contained an entity that could not be
failed verification by the defined `verify` option. The `status` property is
set to `403`, the `type` property is set to `'entity.verify.failed'`, and the
`body` property is set to the entity value that failed verification.

### request aborted

This error will occur when the request is aborted by the client before reading
the body has finished. The `received` property will be set to the number of
bytes received before the request was aborted and the `expected` property is
set to the number of expected bytes. The `status` property is set to `400`
and `type` property is set to `'request.aborted'`.

### request entity too large

This error will occur when the request body's size is larger than the "limit"
option. The `limit` property will be set to the byte limit and the `length`
property will be set to the request body's length. The `status` property is
set to `413` and the `type` property is set to `'entity.too.large'`.

### request size did not match content length

This error will occur when the request's length did not match the length from
the `Content-Length` header. This typically occurs when the request is malformed,
typically when the `Content-Length` header was calculated based on characters
instead of bytes. The `status` property is set to `400` and the `type` property
is set to `'request.size.invalid'`.

### stream encoding should not be set

This error will occur when something called the `req.setEncoding` method prior
to this middleware. This module operates directly on bytes only and you cannot
call `req.setEncoding` when using this module. The `status` property is set to
`500` and the `type` property is set to `'stream.encoding.set'`.

### stream is not readable

This error will occur when the request is no longer readable when this middleware
attempts to read it. This typically means something other than a middleware from
this module read the request body already and the middleware was also configured to
read the same request. The `status` property is set to `500` and the `type`
property is set to `'stream.not.readable'`.

### too many parameters

This error will occur when the content of the request exceeds the configured
`parameterLimit` for the `urlencoded` parser. The `status` property is set to
`413` and the `type` property is set to `'parameters.too.many'`.

### unsupported charset "BOGUS"

This error will occur when the request had a charset parameter in the
`Content-Type` header, but the `iconv-lite` module does not support it OR the
parser does not support it. The charset is contained in the message as well
as in the `charset` property. The `status` property is set to `415`, the
`type` property is set to `'charset.unsupported'`, and the `charset` property
is set to the charset that is unsupported.

### unsupported content encoding "bogus"

This error will occur when the request had a `Content-Encoding` header that
contained an unsupported encoding. The encoding is contained in the message
as well as in the `encoding` property. The `status` property is set to `415`,
the `type` property is set to `'encoding.unsupported'`, and the `encoding`
property is set to the encoding that is unsupported.

### The input exceeded the depth

This error occurs when using `bodyParser.urlencoded` with the `extended` property set to `true` and the input exceeds the configured `depth` option. The `status` property is set to `400`. It is recommended to review the `depth` option and evaluate if it requires a higher value. When the `depth` option is set to `32` (default value), the error will not be thrown.

## Examples

### Express/Connect top-level generic

This example demonstrates adding a generic JSON and URL-encoded parser as a
top-level middleware, which will parse the bodies of all incoming requests.
This is the simplest setup.

```js
const express = require('express')
const bodyParser = require('body-parser')

const app = express()

// parse application/x-www-form-urlencoded
app.use(bodyParser.urlencoded())

// parse application/json
app.use(bodyParser.json())

app.use(function (req, res) {
  res.setHeader('Content-Type', 'text/plain')
  res.write('you posted:\n')
  res.end(String(JSON.stringify(req.body, null, 2)))
})
```

### Express route-specific

This example demonstrates adding body parsers specifically to the routes that
need them. In general, this is the most recommended way to use body-parser with
Express.

```js
const express = require('express')
const bodyParser = require('body-parser')

const app = express()

// create application/json parser
const jsonParser = bodyParser.json()

// create application/x-www-form-urlencoded parser
const urlencodedParser = bodyParser.urlencoded()

// POST /login gets urlencoded bodies
app.post('/login', urlencodedParser, function (req, res) {
  if (!req.body || !req.body.username) res.sendStatus(400)
  res.send('welcome, ' + req.body.username)
})

// POST /api/users gets JSON bodies
app.post('/api/users', jsonParser, function (req, res) {
  if (!req.body) res.sendStatus(400)
  // create user in req.body
})
```

### Change accepted type for parsers

All the parsers accept a `type` option which allows you to change the
`Content-Type` that the middleware will parse.

```js
const express = require('express')
const bodyParser = require('body-parser')

const app = express()

// parse various different custom JSON types as JSON
app.use(bodyParser.json({ type: 'application/*+json' }))

// parse some custom thing into a Buffer
app.use(bodyParser.raw({ type: 'application/vnd.custom-type' }))

// parse an HTML body into a string
app.use(bodyParser.text({ type: 'text/html' }))
```

## License

[MIT](LICENSE)

[ci-image]: https://img.shields.io/github/actions/workflow/status/expressjs/body-parser/ci.yml?branch=master&label=ci
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[npm-url]: https://npmjs.com/package/body-parser
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