# ALBProcessor

**Kind:** Class

**Source:** [`src/adapter/aws-lambda/handler.ts`](https://github.com/honojs/hono/blob/main/src/adapter/aws-lambda/handler.ts#L503)

**Part of:** [Adapter](subsystem-src-adapter)

`ALBProcessor` adapts an AWS Application Load Balancer request into request values used by the Lambda handler. It reads headers, path, method, query string, and cookies, then writes response cookies back to the ALB result.

**Extends:** `EventProcessor`

## Methods

| Method | Signature | Returns |
|---|---|---|
| `getHeaders` | `getHeaders(event: ALBProxyEvent)` | `Headers` |
| `getPath` | `getPath(event: ALBProxyEvent)` | `string` |
| `getMethod` | `getMethod(event: ALBProxyEvent)` | `string` |
| `getQueryString` | `getQueryString(event: ALBProxyEvent)` | `string` |
| `getCookies` | `getCookies(event: ALBProxyEvent, headers: Headers)` | `void` |
| `setCookiesToResult` | `setCookiesToResult(result: APIGatewayProxyResult, cookies: string[])` | `void` |

## Diagram

```mermaid
graph LR
  ALB[ALB request event] --> Processor[ALBProcessor]
  Processor --> Headers[getHeaders()]
  Processor --> Path[getPath()]
  Processor --> Method[getMethod()]
  Processor --> Query[getQueryString()]
  Processor --> Cookies[getCookies()]
  Handler[Application handler] --> ResponseCookies[Response cookies]
  ResponseCookies --> Processor
  Processor --> Result[ALB response result]
  Processor --> SetCookies[setCookiesToResult()]
```

## Usage

```ts
import { ALBProcessor } from './adapter/aws-lambda/handler';

export async function handler(event: unknown) {
  const result = {
    statusCode: 200,
    headers: {},
    body: '',
  };

  const processor = new ALBProcessor(event, result);

  const request = {
    method: processor.getMethod(),
    path: processor.getPath(),
    headers: processor.getHeaders(),
    queryString: processor.getQueryString(),
  };

  processor.getCookies();

  result.body = JSON.stringify({
    method: request.method,
    path: request.path,
    queryString: request.queryString,
  });

  processor.setCookiesToResult();

  return result;
}
```

## AI Coding Instructions

- Read request metadata through `getHeaders()`, `getPath()`, `getMethod()`, and `getQueryString()` instead of accessing ALB event fields in application code.
- Call `getCookies()` before code that depends on request cookies.
- Call `setCookiesToResult()` after response cookies have been added and before returning the ALB result.
- Keep ALB-specific request and response handling inside this adapter so application handlers remain transport-independent.