@fastify/accepts

What is @fastify/accepts?

@fastify/accepts is a Fastify plugin that provides a simple way to handle HTTP Accept headers. It allows you to easily determine the best content type, language, encoding, and charset to respond with based on the client's request.

What are @fastify/accepts's main functionalities?

Content Type Negotiation

This feature allows you to determine the best content type to respond with based on the client's Accept header. The code sample demonstrates how to respond with either JSON or HTML depending on the client's preference.

const fastify = require('fastify')();
const accepts = require('@fastify/accepts');

fastify.register(accepts);

fastify.get('/', (request, reply) => {
  const accept = request.accepts();
  const type = accept.type(['json', 'html']);
  if (type === 'json') {
    reply.send({ message: 'Hello, JSON!' });
  } else if (type === 'html') {
    reply.type('text/html').send('<h1>Hello, HTML!</h1>');
  } else {
    reply.code(406).send('Not Acceptable');
  }
});

fastify.listen(3000, err => {
  if (err) throw err;
  console.log('Server listening on http://localhost:3000');
});

Language Negotiation

This feature allows you to determine the best language to respond with based on the client's Accept-Language header. The code sample demonstrates how to respond with either English or Spanish depending on the client's preference.

const fastify = require('fastify')();
const accepts = require('@fastify/accepts');

fastify.register(accepts);

fastify.get('/', (request, reply) => {
  const accept = request.accepts();
  const lang = accept.language(['en', 'es']);
  if (lang === 'en') {
    reply.send({ message: 'Hello!' });
  } else if (lang === 'es') {
    reply.send({ message: '¡Hola!' });
  } else {
    reply.code(406).send('Not Acceptable');
  }
});

fastify.listen(3000, err => {
  if (err) throw err;
  console.log('Server listening on http://localhost:3000');
});

Encoding Negotiation

This feature allows you to determine the best encoding to respond with based on the client's Accept-Encoding header. The code sample demonstrates how to respond with either GZIP or Deflate encoding depending on the client's preference.

const fastify = require('fastify')();
const accepts = require('@fastify/accepts');

fastify.register(accepts);

fastify.get('/', (request, reply) => {
  const accept = request.accepts();
  const encoding = accept.encoding(['gzip', 'deflate']);
  if (encoding === 'gzip') {
    reply.header('Content-Encoding', 'gzip').send('Hello, GZIP!');
  } else if (encoding === 'deflate') {
    reply.header('Content-Encoding', 'deflate').send('Hello, Deflate!');
  } else {
    reply.code(406).send('Not Acceptable');
  }
});

fastify.listen(3000, err => {
  if (err) throw err;
  console.log('Server listening on http://localhost:3000');
});

Charset Negotiation

This feature allows you to determine the best charset to respond with based on the client's Accept-Charset header. The code sample demonstrates how to respond with either UTF-8 or ISO-8859-1 charset depending on the client's preference.

const fastify = require('fastify')();
const accepts = require('@fastify/accepts');

fastify.register(accepts);

fastify.get('/', (request, reply) => {
  const accept = request.accepts();
  const charset = accept.charset(['utf-8', 'iso-8859-1']);
  if (charset === 'utf-8') {
    reply.header('Content-Type', 'text/plain; charset=utf-8').send('Hello, UTF-8!');
  } else if (charset === 'iso-8859-1') {
    reply.header('Content-Type', 'text/plain; charset=iso-8859-1').send('Hello, ISO-8859-1!');
  } else {
    reply.code(406).send('Not Acceptable');
  }
});

fastify.listen(3000, err => {
  if (err) throw err;
  console.log('Server listening on http://localhost:3000');
});

Other packages similar to @fastify/accepts

accepts

The 'accepts' package is a content negotiation library for Node.js. It provides similar functionality to @fastify/accepts but is framework-agnostic, meaning it can be used with any Node.js server framework, not just Fastify.

negotiator

The 'negotiator' package is another content negotiation library for Node.js. It provides a more low-level API compared to 'accepts' and @fastify/accepts, giving you more control over the negotiation process but requiring more manual handling.

README

@fastify/accepts

Add an accepts parser to Fastify.

Install

npm i @fastify/accepts

Compatibility

Plugin version	Fastify version
^5.x	^5.x
^4.x	^4.x
^2.x	^3.x
^1.x	^2.x
^1.x	^1.x

Please note that if a Fastify version is out of support, then so are the corresponding version(s) of this plugin in the table above. See Fastify's LTS policy for more details.

Usage

const fastify = require('fastify')
const Boom = require('@hapi/boom')

fastify.register(require('@fastify/accepts'))

fastify.post('/', function (req, reply) {
  const accept = req.accepts() // Accepts object
  switch(accept.type(['json', 'html'])) {
    case 'json':
      reply.type('application/json').send({hello: 'world'})
      break
    case 'html':
      reply.type('text/html').send('<b>hello, world!</b>')
      break
    default:
      reply.send(Boom.notAcceptable('unacceptable'))
      break
  }
})

See accepts package for all available APIs.

This plugin adds to Request object all Accepts object methods.

fastify.post('/', function (req, reply) {
  req.charset(['utf-8'])
  req.charsets()
  req.encoding(['gzip', 'compress'])
  req.encodings()
  req.language(['es', 'en'])
  req.languages()
  req.type(['image/png', 'image/tiff'])
  req.types()
})

Options

• decorateReply If true, the Reply object will be decorated with the requestAccepts, requestTypes, requestCharsets, requestEncodings, and requestLanguages methods, which will return the corresponding values from the Request object. Default: false.

License

Licensed under MIT.