@fastify/accepts-serializer

Serialize according to the Accept header.

Install

npm i @fastify/accepts-serializer

Compatibility

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

Usage

const protobuf = require('protobufjs')
const YAML = require('yamljs')
const msgpack = require('msgpack5')()

const root = protobuf.loadSync('test/awesome.proto')
const AwesomeMessage = root.lookupType('awesomepackage.AwesomeMessage')

const fastify = require('fastify')()

// Global serializers
fastify.register(require('@fastify/accepts-serializer'), {
  serializers: [
    {
      regex: /^application\/yaml$/,
      serializer: body => YAML.stringify(body)
    },
    {
      regex: /^application\/x-msgpack$/,
      serializer: body => msgpack.encode(body)
    }
  ],
  default: 'application/yaml', // MIME type used if Accept header does not match anything
  cacheSize: 100               // max number of Accept header combinations to cache (default: 100)
})

// Per-router serializers
const config = {
  serializers: [
    {
      regex: /^application\/x-protobuf$/,
      serializer: body => AwesomeMessage.encode(AwesomeMessage.create(body)).finish()
    }
  ]
}

fastify.get('/request', { config }, function (req, reply) {
  reply.send({pippo: 'pluto'})
})

Options

Behavior

For each route, a SerializerManager is defined, which has both per-route and global serializer definitions.

The MIME type application/json is always handled by fastify if no serializer is registered for that MIME type.

If no default key is specified in configuration, all requests with an unknown Accept header will be replied to with a 406 response (a boom error is used).

Serializer selection results are cached by Accept header value using an LRU cache bounded by cacheSize. This prevents unbounded memory growth from attacker-controlled Accept header variants.

License

Licensed under MIT.