17 KiB
body-parser
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.
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:
This module provides the following parsers:
Other body parsers you might be interested in:
Installation
$ npm install body-parserAPI
var bodyParser = require('body-parser')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, or an empty object ({}) if there was no body to
parse, the Content-Type was not matched, or an error
occurred.
The various errors returned by this module are described in the errors section.
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 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:
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
library for parsing. Defaults to '100kb'.
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.
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 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 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
library for parsing. Defaults to '100kb'.
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 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 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
library for parsing. Defaults to '100kb'.
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 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
encoding of the body and supports automatic inflation of
gzip 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 option allows to choose between parsing the
URL-encoded data with the querystring library (when
false) or the qs library (when
true). 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.
Defaults to true, but using the default has been
deprecated. Please research into the difference between qs
and querystring and choose the appropriate setting.
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
library for parsing. Defaults to '100kb'.
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 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.
Errors
The middlewares provided by this module create errors depending on
the error condition during parsing. 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 emitted, 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.
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'.
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.
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.
var express = require('express')
var bodyParser = require('body-parser')
var app = express()
// parse application/x-www-form-urlencoded
app.use(bodyParser.urlencoded({ extended: false }))
// 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(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.
var express = require('express')
var bodyParser = require('body-parser')
var app = express()
// create application/json parser
var jsonParser = bodyParser.json()
// create application/x-www-form-urlencoded parser
var urlencodedParser = bodyParser.urlencoded({ extended: false })
// POST /login gets urlencoded bodies
app.post('/login', urlencodedParser, function (req, res) {
res.send('welcome, ' + req.body.username)
})
// POST /api/users gets JSON bodies
app.post('/api/users', jsonParser, function (req, res) {
// 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.
var express = require('express')
var bodyParser = require('body-parser')
var 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' }))