A simple plugin for Fastify that adds a content type parser for the content type application/x-www-form-urlencoded.

npm i @fastify/formbody

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.

Given the following code:

const fastify = require('fastify')()
fastify.register(require('@fastify/formbody'))
fastify.post('/', (req, reply) => {
  reply.send(req.body)
})
fastify.listen({ port: 8000 }, (err) => {
  if (err) throw err
})

And a POST body of:

foo=foo&bar=bar&answer=42

The sent reply would be the object:

{
  foo: 'foo',
  bar: 'bar',
  answer: 42
}

The plugin accepts an options object with the following properties:

• bodyLimit: The maximum amount of bytes to process before returning an error. If the limit is exceeded, a 500 error will be returned immediately. When set to undefined the limit will be set to whatever is configured on the parent Fastify instance. The default value is whatever is configured in fastify (1048576 by default).
• parser: The default parser used is the querystring.parse built-in. You can change this default by passing a parser function e.g. fastify.register(require('@fastify/formbody'), { parser: str => myParser(str) })

Previously, the external qs lib was used that did things like parse nested objects. For example:

• Input: foo[one]=foo&foo[two]=bar
• Parsed: { foo: { one: 'foo', two: 'bar' } }

The way this is handled now using the built-in querystring.parse:

• Input: foo[one]=foo&foo[two]=bar
• Parsed: { 'foo[one]': 'foo', 'foo[two]': 'bar' }

If you need nested parsing, you must configure it manually by installing the qs lib (npm i qs), and then configure an optional parser:

const fastify = require('fastify')()
const qs = require('qs')
fastify.register(require('@fastify/formbody'), { parser: str => qs.parse(str) })

Licensed under MIT.