@practica/create-node-app/src/code-templates/libraries/common-express-middlewares/lib/request-context/request-context-middleware.ts

Create Node.js app that is packed with best practices AND strive for simplicity

import { IncomingMessage, ServerResponse } from 'http';
import { context } from '@practica/global-context';
import { randomUUID } from 'node:crypto';

/**
 * This is an express middleware that:
 * - Generate/Use request id (depending on if you already have one in the request header)
 * - Add it to the request context
 *
 * **Important:** this should be your first middleware
 */

const REQUEST_ID_HEADER = 'x-request-id';

export function addRequestId(
  req: IncomingMessage,
  res: ServerResponse,
  next: () => void
) {
  let requestId = req.headers[REQUEST_ID_HEADER];

  if (!requestId) {
    requestId = randomUUID();
    req.headers[REQUEST_ID_HEADER] = requestId;
  }

  res.setHeader(REQUEST_ID_HEADER, requestId);

  const currentContext = context().getStore();

  if (currentContext) {
    // Append to the current context
    currentContext.requestId = requestId;
    next();
    return;
  }

  context().run({ requestId }, next);
}