xprezzo-json-parser

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

$ npm install xprezzo-json-parser

API

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.

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'.

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 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.

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

Xprezzo/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 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))
})

Xprezzo 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 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
})

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 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' }))

License

MIT