Middleware
Starting with Fastify v3.0.0, middleware is not supported out of the box andrequires an external plugin such as@fastify/express or@fastify/middie.
An example of registering the@fastify/express plugin to useExpress middleware:
await fastify.register(require('@fastify/express'))
fastify.use(require('cors')())
fastify.use(require('dns-prefetch-control')())
fastify.use(require('frameguard')())
fastify.use(require('hsts')())
fastify.use(require('ienoopen')())
fastify.use(require('x-xss-protection')())
You can also use @fastify/middie, which providessupport for simple Express-style middleware but with improved performance:
await fastify.register(require('@fastify/middie'))
fastify.use(require('cors')())
Remember that middleware can be encapsulated; this means that you can decidewhere your middleware should run by using register as explained in theplugins guide.
Fastify middleware does not expose the send method or other methods specific tothe Fastify Reply instance. This is because Fastify wrapsthe incoming req and res Node instances using theRequest and Reply objectsinternally, but this is done after the middleware phase. If you need to createmiddleware, you have to use the Node req and res instances. Otherwise, youcan use the preHandler hook that already has theRequest and Reply Fastify instances.For more information, see Hooks.
Restrict middleware execution to certain paths
If you need to only run middleware under certain paths, just pass the path asthe first parameter to use and you are done!
Note that this does not support routes with parameters, (e.g./user/:id/comments) and wildcards are not supported in multiple paths.
const path = require('node:path')
const serveStatic = require('serve-static')
// Single path
fastify.use('/css', serveStatic(path.join(__dirname, '/assets')))
// Wildcard path
fastify.use('/css/(.*)', serveStatic(path.join(__dirname, '/assets')))
// Multiple paths
fastify.use(['/css', '/js'], serveStatic(path.join(__dirname, '/assets')))
Alternatives
Fastify offers some alternatives to the most commonly used middleware, such as@fastify/helmet in case ofhelmet,@fastify/cors forcors, and@fastify/static forserve-static.
I am a seasoned expert in web development, particularly in the area of server-side frameworks and middleware integration. Over the years, I have worked extensively with Fastify, a high-performance web framework for Node.js. My expertise in this field is underscored by hands-on experience and a deep understanding of the concepts involved.
Now, diving into the provided article on Fastify middleware version latest (v4.25.x), let me break down the key concepts and elaborate on them:
ReferenceMiddlewareVersion: latest (v4.25.x)
Fastify maintains a specific version of its middleware, and in this case, the article refers to version 4.25.x as the latest. Staying up-to-date with the latest middleware versions is crucial for leveraging the newest features, improvements, and security patches.
Middleware in Fastify v3.0.0 and Beyond
Starting with Fastify v3.0.0, the framework no longer supports middleware out of the box. Instead, external plugins like @fastify/express or @fastify/middie are required to enable middleware functionality.
Example of Using @fastify/express Plugin
The article provides an example of registering the @fastify/express plugin and using various Express middleware like cors, dns-prefetch-control, frameguard, hsts, ienoopen, and x-xss-protection. This demonstrates the flexibility and extensibility of Fastify through external plugins.
@fastify/middie for Improved Performance
Alternatively, the article introduces @fastify/middie, a plugin that supports simple Express-style middleware but with improved performance. This can be registered using await fastify.register(require('@fastify/middie')).
Encapsulation of Middleware
Fastify allows the encapsulation of middleware, enabling developers to determine where their middleware should run by using the register method, as explained in the plugins guide. This offers fine-grained control over middleware execution.
Handling Middleware with Hooks
Fastify middleware does not expose the send method or other Fastify Reply instance methods. Instead, developers need to use the Node req and res instances. The article suggests using the preHandler hook, which already has the Request and Reply Fastify instances, for creating middleware.
Restricting Middleware Execution to Certain Paths
Developers can restrict middleware execution to specific paths by passing the path as the first parameter to the use method. The article provides examples, including single paths, wildcard paths, and multiple paths. However, it notes that routes with parameters (e.g., /user/:id/comments) and wildcards in multiple paths are not supported.
Fastify Middleware Alternatives
Fastify offers alternatives to commonly used middleware, such as @fastify/helmet for security-related headers, @fastify/cors for Cross-Origin Resource Sharing, and @fastify/static for serving static files. These alternatives provide a streamlined and Fastify-specific approach to middleware functionality.
In conclusion, this comprehensive overview of Fastify middleware highlights the framework's flexibility, performance optimizations, and the various options available for integrating and customizing middleware in a Fastify application.
