# MiddlewareConfiguration

**Kind:** Interface

**Source:** [`packages/common/interfaces/middleware/middleware-configuration.interface.ts`](https://github.com/nestjs/nest/blob/master/packages/common/interfaces/middleware/middleware-configuration.interface.ts#L11)

**Part of:** [Common](subsystem-packages-common)

`MiddlewareConfiguration` defines how a middleware component is bound to one or more application routes. It pairs a middleware class or instance with route targets expressed as controllers, path strings, or `RouteInfo` objects.

## Properties

| Property | Type |
|---|---|
| `middleware` | `T` |
| `forRoutes` | `(Type<any> | string | RouteInfo)[]` |

## Diagram

```mermaid
graph LR
  MC[MiddlewareConfiguration]
  M[middleware: T]
  FR[forRoutes: Route Targets]
  C[Controller Type]
  P[Path String]
  RI[RouteInfo]

  MC --> M
  MC --> FR
  FR --> C
  FR --> P
  FR --> RI
```

## Usage

```ts
import { MiddlewareConfiguration, RouteInfo } from '@nestjs/common';

class LoggerMiddleware {
  use(req: Request, res: Response, next: () => void) {
    console.log(`${req.method} ${req.url}`);
    next();
  }
}

const configuration: MiddlewareConfiguration = {
  middleware: LoggerMiddleware,
  forRoutes: [
    'users',
    { path: 'admin', method: RequestMethod.ALL } as RouteInfo,
  ],
};
```

## AI Coding Instructions

- Set `middleware` to the middleware class, function, or compatible middleware value expected by the consuming configuration API.
- Use `forRoutes` to target controllers, route path strings, or `RouteInfo` objects with explicit HTTP method matching.
- Prefer `RouteInfo` when middleware should apply only to a specific HTTP method rather than every method for a path.
- Ensure route strings and controller references match the routes registered by the application module.
- Keep middleware configuration close to module setup so route bindings remain discoverable and maintainable.

## Used by

3 references from 3 files. Each is a place in this repository where the symbol is actually used — go read one rather than trusting an example.

### Imported by (3)

- `MiddlewareBuilder` — `packages/core/middleware/builder.ts`:17
- `moduleName` — `packages/core/middleware/container.ts`:68
- `handler` — `packages/core/middleware/middleware-module.ts`:287