Cache aware display of "product is new" badge

Question

This is a follow up of

Magento2 : How to show New label in product list page

If I understand the proposed solution correctly, the product will still be shown as new as long as the full page cache does not expire.

What is an elegant solution for this?

I have something like the following in mind:

• Detect somehow if product is no longer new (for example a cron that runs once a day, detect if the current day is just product-is-new-until plus one) or cache the latest state of product-is-new

• If the product is now longer new, clear the product related cache tag.

Would that work? Did anybody do something like this, yet?

Answer 1

step 1: create a cronjob which needs to run once in a day

step 2: get collection of products expired yesterday (something like this "NewsToDate" == date("Y-m-d", strtotime("-1 day")) )

step 3 : iterate collection and invalidate product cache

$product->cleanCache();
$this->_eventManager->dispatch('clean_cache_by_tags', ['object' => $product]);