# RouterExceptionFilters

**Kind:** Class

**Source:** [`packages/core/router/router-exception-filters.ts`](https://github.com/nestjs/nest/blob/master/packages/core/router/router-exception-filters.ts#L14)

**Part of:** [Core](subsystem-packages-core)

`RouterExceptionFilters` builds an `ExceptionsHandler` for a routed controller method. It resolves method-, controller-, and application-level exception filters, including scoped global filters, and attaches them in the correct execution order.

**Extends:** `BaseExceptionFilterContext`

## Methods

| Method | Signature | Returns |
|---|---|---|
| `create` | `create(instance: Controller, callback: RouterProxyCallback, moduleKey: string | undefined, contextId: undefined, inquirerId: string)` | `ExceptionsHandler` |
| `getGlobalMetadata` | `getGlobalMetadata(contextId: undefined, inquirerId: string)` | `T` |

## Where it refuses work

- `RouterExceptionFilters` stops the work with an early return when `isEmpty(filters)`.
- `RouterExceptionFilters` stops the work with an early return when `contextId === STATIC_CONTEXT && !inquirerId`.

## Diagram

```mermaid
graph LR
  A[Incoming route handler] --> B[RouterExceptionFilters.create]
  B --> C[Resolve method/controller filter metadata]
  B --> D[Resolve global filters]
  C --> E[ExceptionsHandler]
  D --> E
  E --> F[Execute matching exception filter]
  F --> G[Send HTTP error response]
```

## Usage

```ts
import { RouterExceptionFilters } from '@nestjs/core/router/router-exception-filters';

// Typically created internally by Nest during application bootstrap.
const exceptionFilters = new RouterExceptionFilters(
  container,
  applicationConfig,
  httpAdapter,
);

// Create the handler used to process exceptions thrown by a route callback.
const handler = exceptionFilters.create(
  usersController,
  usersController.findOne,
  moduleKey,
);

// The returned ExceptionsHandler is used by the router proxy.
try {
  await usersController.findOne('123');
} catch (error) {
  handler.next(error, requestContext);
}
```

## AI Coding Instructions

- Treat `RouterExceptionFilters` as router infrastructure; application code should normally register filters with `@UseFilters()` or `app.useGlobalFilters()` instead of instantiating it directly.
- Preserve filter resolution order when changing this class: method and controller metadata must be combined with global filter metadata predictably.
- Ensure request-scoped and transient global filters are resolved using the active context ID and inquirer ID when applicable.
- Return an `ExceptionsHandler` even when no custom filters are registered so default HTTP exception handling remains available.
- Keep integrations aligned with `ApplicationConfig`, `NestContainer`, and the active HTTP adapter, since they provide global filters, dependency resolution, and response handling.

## Relationships

- IMPORTS → `HttpServer`
- IMPORTS → `EXCEPTION_FILTERS_METADATA`
- IMPORTS → `Controller`
- IMPORTS → `isEmpty`