EventV2Processor

Kind: Class

Source: src/adapter/aws-lambda/handler.ts

Part of: Adapter

This class adapts AWS Lambda HTTP request data into the request values consumed by the handler layer. It exposes path, method, query string, headers, and cookie handling while writing response cookies back to the Lambda result.

Extends: EventProcessor

Methods

Diagram

mermaid
graph LR
  Event["EventV2Processor [census]"] --> Request["Request accessors"]
  Event --> Cookies["Cookie handling"]
  Request --> Path["getPath"]
  Request --> Method["getMethod"]
  Request --> Query["getQueryString"]
  Request --> Headers["getHeaders"]
  Cookies --> ReadCookies["getCookies"]
  Cookies --> WriteCookies["setCookiesToResult"]

Usage

ts
declare const processor: EventV2Processor; // [census]

const requestDetails = {
  path: processor.getPath(),
  method: processor.getMethod(),
  queryString: processor.getQueryString(),
  contentType: processor.getHeaders().get("content-type"),
};

processor.getCookies();

// Handle the request and prepare response cookies.

processor.setCookiesToResult();

AI Coding Instructions

• Keep AWS Lambda event-specific parsing inside this adapter layer.
• Read cookies before handler code depends on them, then write response cookies before returning the Lambda result.
• Treat getHeaders() as the source for request header access rather than reading the Lambda event directly.
• Preserve the existing path, method, and query string mapping behavior when changing request handling.

How it works

EventV2Processor is an exported concrete EventProcessor subclass for APIGatewayProxyEventV2 events. It supplies the v2-specific path, method, query, header, and cookie mappings used by the inherited request/result conversion methods. src/adapter/aws-lambda/handler.ts:404-439

• getProcessor() selects the module-level EventV2Processor instance when an event has both rawPath and requestContext.http, after checking whether it is an ALB event. src/adapter/aws-lambda/handler.ts:625-637 src/adapter/aws-lambda/handler.ts:646-651
• For a v2 event, it takes the request path from rawPath, the HTTP method from requestContext.http.method, and the query string directly from rawQueryString. src/adapter/aws-lambda/handler.ts:405-415
• Its header conversion starts with a new Headers object. If event.cookies is an array, it writes one Cookie header whose value joins the entries with ; . It then copies each truthy entry from event.headers with Headers.set(). src/adapter/aws-lambda/handler.ts:417-438
• Through EventProcessor.createRequest(), the processor constructs a URL as https://${domainName}${rawPath}, appending ?${rawQueryString} only when that string is non-empty. The domain comes first from event.requestContext.domainName; otherwise the shared logic checks host in headers, then multiValueHeaders. src/adapter/aws-lambda/handler.ts:301-323
• When event.body is truthy, the inherited request conversion decodes it from base64 if isBase64Encoded is true; otherwise it UTF-8 encodes the string. It assigns that byte sequence as the Request body and sets content-length to its byte length. src/adapter/aws-lambda/handler.ts:327-341
• The inherited result conversion marks a response body as base64-encoded when the configured binary-content predicate, or the default predicate, classifies its content-type as binary. If it is not already marked binary, a non-identity content-encoding also marks it binary. Binary bodies are read as an ArrayBuffer and base64 encoded; other bodies are read as text. src/adapter/aws-lambda/handler.ts:344-360 src/adapter/aws-lambda/handler.ts:666-674
• For response cookies, this subclass writes extracted Set-Cookie values to the result’s cookies array. The shared logic removes set-cookie from the response headers before copying remaining headers into the Lambda result. src/adapter/aws-lambda/handler.ts:388-400 src/adapter/aws-lambda/handler.ts:423-425
• In the standard handle() path, exceptions while creating the request or reading its request context are logged. A TypeError becomes a 400 result with body Invalid request; other caught errors become a 500 result with body Internal Server Error. src/adapter/aws-lambda/handler.ts:252-266 An invalid v2 header name is covered by a test that expects this 400 result. src/adapter/aws-lambda/handler.test.ts:441-467