fastify-plugin

What is fastify-plugin?

The fastify-plugin npm package is designed to facilitate the creation of plugins for the Fastify web framework. It ensures that plugins adhere to specific conventions and are compatible with the Fastify ecosystem. This package helps in encapsulating functionality, adding hooks, decorators, and more, in a way that's easily reusable across different Fastify projects.

What are fastify-plugin's main functionalities?

Plugin Creation

This feature allows developers to create a Fastify plugin. The code sample demonstrates how to use fastify-plugin to decorate the Fastify instance with a new function called 'utility'.

const fp = require('fastify-plugin');

async function myPlugin (fastify, options) {
  fastify.decorate('utility', () => 'something useful');
}

module.exports = fp(myPlugin);

Plugin Options

This feature enables passing options to the plugin, including specifying Fastify version compatibility. The code sample shows how to pass data through options and use it within the plugin.

const fp = require('fastify-plugin');

async function myPlugin (fastify, options) {
  fastify.decorate('usefulData', options.data);
}

module.exports = fp(myPlugin, { name: 'myPlugin', fastify: '3.x' });

Encapsulation

This feature ensures that the plugin does not encapsulate its context, allowing the decorators, hooks, and changes made by the plugin to be available in the parent scope. The code sample demonstrates registering another plugin within a fastify-plugin, ensuring dependencies are managed.

const fp = require('fastify-plugin');

async function myPlugin (fastify, options) {
  fastify.register(require('some-other-plugin'), options);
}

module.exports = fp(myPlugin, { dependencies: ['some-other-plugin'] });

Other packages similar to fastify-plugin

fastify-decorators

Provides decorators for Fastify, aiming to simplify the creation of controllers, services, and plugins. While it offers a different approach by leveraging TypeScript decorators, it shares the goal of enhancing Fastify's extensibility.

middie

A plugin to add middleware support to Fastify. While fastify-plugin is a tool for creating Fastify plugins, middie focuses specifically on enabling the use of Express/Connect-style middleware within Fastify applications.

fastify-autoload

Automatically loads plugins and routes, simplifying the application structure. Unlike fastify-plugin, which is about creating plugins, fastify-autoload helps in organizing and loading them efficiently in a Fastify application.

README

fastify-plugin

fastify-plugin is a plugin helper for Fastify.

When you build plugins for Fastify and you want that them to be accessible in the same context where you require them, you have two ways:

• Use the skip-override hidden property
• Use this module

Note: the v2.x series of this module covers Fastify v3. For Fastify v2 support refert to the v1.x series.

Usage

fastify-plugin can do three things for you:

• Add the skip-override hidden property
• Check the bare-minimum version of Fastify
• Pass some custom metadata of the plugin to Fastify

Example:

const fp = require('fastify-plugin')

module.exports = fp(function (fastify, opts, next) {
  // your plugin code
  next()
})

Metadata

In addition if you use this module when creating new plugins, you can declare the dependencies, the name and the expected Fastify version that your plugin needs.

Fastify version

If you need to set a bare-minimum version of Fastify for your plugin, just add the semver range that you need:

const fp = require('fastify-plugin')

module.exports = fp(function (fastify, opts, next) {
  // your plugin code
  next()
}, { fastify: '3.x' })

If you need to check the Fastify version only, you can pass just the version string.

You can check here how to define a semver range.

Name

Fastify uses this option to validate dependency graph. On one hand it makes sure that no name collision occurs. On the other hand it makes possible to perform dependency check.

const fp = require('fastify-plugin')

function plugin (fastify, opts, next) {
  // your plugin code
  next()
}

module.exports = fp(plugin, {
  fastify: '3.x',
  name: 'your-plugin-name'
})

Dependencies

You can also check if the plugins and decorators which your plugin intend to use are present in the dependency graph.

Note: This is the point where registering name of the plugins become important, because you can reference plugin dependencies by their name.

const fp = require('fastify-plugin')

function plugin (fastify, opts, next) {
  // your plugin code
  next()
}

module.exports = fp(plugin, {
  fastify: '3.x',
  decorators: {
    fastify: ['plugin1', 'plugin2'],
    reply: ['compress']
  },
  dependencies: ['plugin1-name', 'plugin2-name']
})

Acknowledgements

This project is kindly sponsored by:

• nearForm
• LetzDoIt

License

Licensed under MIT.