xprezzo-json-parser

A 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).

Installation

``sh
$ npm install xprezzo-json-parser
`

API

`js
var JsonParser = require('xprezzo-json-parser')
`

The JsonParser 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.

#### 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.

Errors

The middlewares provided by this module create errors using the
xprezzo-http-errors module. 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.

$3

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.

$3

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.

$3

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.

$3

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'.

$3

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'.

$3

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'.

$3

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'.

$3

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'.

$3

This error will occur when the request had a charset parameter in the
Content-Type header, but the xprezzo-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.

$3

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

$3

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
var Xprezzo = require('xprezzo')
var JsonParser = require('xprezzo-json-parser')

var app = Xprezzo()

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

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

$3

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
var Xprezzo = require('xprezzo')
var JsonParser = require('xprezzo-json-parser')

var app = Xprezzo()

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

$3

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

`js
var Xprezzo = require('xprezzo')
var JsonParser = require('xprezzo-json-parser')

var app = Xprezzo()

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

People

Xprezzo and related projects are maintained by Cloudgen Wong.

License

MIT