A rough implementation of discount links in Hydrogen

discount-link.tsx

// Place this file at `/routes/discounts/[handle].tsx`

import {useUrl, useRouteParams, useSession} from '@shopify/hydrogen';

// @TODO: Add in API route for setting session cookie with discount code: https://shopify.dev/custom-storefronts/hydrogen/framework/sessions#reading-and-updating-session-data

export async function api(request, {session}) {
  let sessionData, jsonData;

}

export default function DiscountLink({response}} {
  const url = useUrl();
  const {handle} = useRouteParams();

  if (response && response.writeHead) {
    response.doNotStream();
    response.writeHead({status: 302});
  }

  if (handle) {
    // @TODO: Call API route here to set discount code (handle) as discountCode cookie on session
  }

  const target = url.searchParams.get('redirect_to')

  if (target) {
    return response.redirect(target)
  } else {
    return response.redirect('/')
  }
}

/* 

Note, if implementing client side redirects in Online Store similar to: https://gist.github.com/benjaminsehl/cdd0ce53951659db1266276cda854285
Then an additional API route will be needed, or similar logic, to grab the `discount_code` URL parameter, and save it in the `discountCode` cookie slot
A better design for both cases may be to have a dedicated /api/discount_link.server.tsx API route which handles both the Online Store redirect case, and the
Hydrogen-native discount link case.

 */