# FastifyAdapter

**Kind:** Class

**Source:** [`packages/platform-fastify/adapters/fastify-adapter.ts`](https://github.com/nestjs/nest/blob/master/packages/platform-fastify/adapters/fastify-adapter.ts#L124)

**Part of:** [Platform Fastify](subsystem-packages-platform-fastify)

`FastifyAdapter` bridges the framework’s HTTP abstractions to a Fastify server instance. It initializes the Fastify application, registers request/response lifecycle hooks, exposes common HTTP route methods, and starts the server through overloaded `listen()` methods.

**Extends:** `AbstractHttpAdapter`

## Methods

| Method | Signature | Returns |
|---|---|---|
| `setOnRequestHook` | `setOnRequestHook(hook: ( request: TRequest, reply: TReply, done: (err?: Error) => void, ) => void | Promise<void>)` | `void` |
| `setOnResponseHook` | `setOnResponseHook(hook: ( request: TRequest, reply: TReply, done: (err?: Error) => void, ) => void | Promise<void>)` | `void` |
| `init` | `init()` | `void` |
| `listen` | `listen(port: string | number, callback: () => void)` | `void` |
| `listen` | `listen(port: string | number, hostname: string, callback: () => void)` | `void` |
| `listen` | `listen(listenOptions: string | number | FastifyListenOptions, args: any[])` | `void` |
| `get` | `get(args: any[])` | `void` |
| `post` | `post(args: any[])` | `void` |
| `head` | `head(args: any[])` | `void` |
| `delete` | `delete(args: any[])` | `void` |
| `put` | `put(args: any[])` | `void` |
| `patch` | `patch(args: any[])` | `void` |
| `options` | `options(args: any[])` | `void` |
| `search` | `search(args: any[])` | `void` |
| `propfind` | `propfind(args: any[])` | `void` |
| `proppatch` | `proppatch(args: any[])` | `void` |
| `mkcol` | `mkcol(args: any[])` | `void` |
| `copy` | `copy(args: any[])` | `void` |
| `move` | `move(args: any[])` | `void` |
| `lock` | `lock(args: any[])` | `void` |
| `unlock` | `unlock(args: any[])` | `void` |
| `applyVersionFilter` | `applyVersionFilter(handler: Function, version: VersionValue, versioningOptions: VersioningOptions)` | `VersionedRoute<TRequest, TReply>` |
| `reply` | `reply(response: TRawResponse | TReply, body: any, statusCode: number)` | `void` |
| `status` | `status(response: TRawResponse | TReply, statusCode: number)` | `void` |
| `end` | `end(response: TReply, message: string)` | `void` |
| `render` | `render(response: TReply & { view: Function }, view: string, options: any)` | `void` |
| `redirect` | `redirect(response: TReply, statusCode: number, url: string)` | `void` |
| `setErrorHandler` | `setErrorHandler(handler: Parameters<TInstance['setErrorHandler']>[0])` | `void` |
| `setNotFoundHandler` | `setNotFoundHandler(handler: Function)` | `void` |
| `getHttpServer` | `getHttpServer()` | `T` |
| `getInstance` | `getInstance()` | `T` |
| `register` | `register(plugin: TRegister['0'], opts: TRegister['1'])` | `void` |
| `inject` | `inject()` | `LightMyRequestChain` |
| `inject` | `inject(opts: InjectOptions | string)` | `Promise<LightMyRequestResponse>` |
| `inject` | `inject(opts: InjectOptions | string)` | `LightMyRequestChain | Promise<LightMyRequestResponse>` |
| `close` | `close()` | `void` |
| `initHttpServer` | `initHttpServer()` | `void` |
| `useStaticAssets` | `useStaticAssets(options: FastifyStaticOptions)` | `void` |
| `setViewEngine` | `setViewEngine(options: FastifyViewOptions | string)` | `void` |
| `isHeadersSent` | `isHeadersSent(response: TReply)` | `boolean` |
| `getHeader` | `getHeader(response: any, name: string)` | `void` |
| `setHeader` | `setHeader(response: TReply, name: string, value: string)` | `void` |
| `appendHeader` | `appendHeader(response: any, name: string, value: string)` | `void` |
| `getRequestHostname` | `getRequestHostname(request: TRequest)` | `string` |
| `getRequestMethod` | `getRequestMethod(request: TRequest)` | `string` |
| `getRequestUrl` | `getRequestUrl(request: TRequest)` | `string` |
| `getRequestUrl` | `getRequestUrl(request: TRawRequest)` | `string` |
| `getRequestUrl` | `getRequestUrl(request: TRequest & TRawRequest)` | `string` |
| `enableCors` | `enableCors(options: FastifyCorsOptions)` | `void` |
| `registerParserMiddleware` | `registerParserMiddleware(prefix: string, rawBody: boolean)` | `void` |

## Properties

| Property | Type |
|---|---|
| `logger` | `any` |
| `instance` | `TInstance` |
| `_pathPrefix` | `string` |

## Where it refuses work

- `FastifyAdapter` stops the work with `Error` when `!isString(value) && !Array.isArray(value)` — “Version constraint should be a string or an array of strings.”.
- `FastifyAdapter` stops the work with an early return when `Array.isArray(version)`.
- `FastifyAdapter` stops the work with an early return when `this.versioningOptions?.type === VersioningType.CUSTOM`.
- `FastifyAdapter` stops the work with an early return when `this.isMiddieRegistered`.
- `FastifyAdapter` stops the work with an early return when `err.code !== 'ERR_SERVER_NOT_RUNNING'`.
- `FastifyAdapter` stops the work with an early return when `this._isParserRegistered`.

## When something fails

- `FastifyAdapter` handles failure in 2 places: it lets it reach the caller in all 2.

## Diagram

```mermaid
graph LR
  App[Application] --> Adapter[FastifyAdapter]
  Adapter --> Hooks[Request / Response Hooks]
  Adapter --> Routes[GET / POST / HEAD / DELETE Routes]
  Adapter --> Fastify[Fastify Server]
  Fastify --> Client[HTTP Clients]
```

## Usage

```ts
import { FastifyAdapter } from '@platform-fastify/adapters/fastify-adapter';

const adapter = new FastifyAdapter();

adapter.setOnRequestHook(async (request, reply) => {
  request.log.info({ url: request.url }, 'Incoming request');

  // Example authentication guard
  if (request.headers['x-api-key'] !== process.env.API_KEY) {
    return reply.code(401).send({ message: 'Unauthorized' });
  }
});

adapter.setOnResponseHook(async (request, reply) => {
  request.log.info(
    { url: request.url, statusCode: reply.statusCode },
    'Response sent',
  );
});

adapter.get('/health', async () => {
  return { status: 'ok' };
});

adapter.post('/users', async (request, reply) => {
  const user = request.body;

  reply.code(201);
  return { user };
});

await adapter.init();
adapter.listen(3000);
```

## AI Coding Instructions

- Register lifecycle hooks with `setOnRequestHook()` and `setOnResponseHook()` before calling `init()` or `listen()`.
- Use the adapter’s route helpers (`get`, `post`, `head`, and `delete`) instead of registering routes directly on the underlying Fastify instance when working within the abstraction.
- Ensure handlers return serializable response values or explicitly send a response through Fastify’s reply object.
- Call `init()` before starting the server when initialization is not handled automatically by the surrounding application bootstrap.
- Preserve Fastify request/reply semantics in hooks and route handlers, including returning early after sending an error response.

## Relationships

- IMPORTS → `HttpStatus`
- IMPORTS → `Logger`
- IMPORTS → `RawBodyRequest`
- IMPORTS → `RequestMethod`
- IMPORTS → `StreamableFile`
- IMPORTS → `VERSION_NEUTRAL`
- IMPORTS → `VersioningOptions`
- IMPORTS → `VersioningType`
- IMPORTS → `VersionValue`
- IMPORTS → `loadPackage`
- IMPORTS → `isString`
- IMPORTS → `isUndefined`
- IMPORTS → `AbstractHttpAdapter`
- IMPORTS → `LegacyRouteConverter`