Magento 2.3 - limit certain categories products

Question

We have a few categories which function like "bestsellers" categories; these categories can hold any number of products, but I'd like to show only the top four.

So I figured to create an observer with the catalog_block_product_list_collection event and try to limit it. The observer triggers fine on the category pages, but whatever I try the collection isn't limited;

    $limitedCollection = $observer->getEvent()->getCollection();
    $limitedCollection->getSelect()->limit(4);
    return $this;

Or

    $limitedCollection = $observer->getEvent()->getCollection();
    $limitedCollection->setPageSize(4)->setCurPage(1);
    return $this;

Neither have any effect. What am I missing? Edit: It's also important that the search/layered navigation etc functionality sees only 4 products.

Answer 1

public function _loadEntities($printQuery = false, $logQuery = false)
{
    if ($this->_pageSize) {
    $this->getSelect()->limitPage($this->getCurPage(), $this->_pageSize);
}

You can prevent this by setting _pageSize to 0:

$productCollection->setPageSize(0);
$productCollection->getSelect()->limit(20,22);

Besides that, resetting the already loaded collection to load it again is not a good idea.

You can write an observer for catalog_product_collection_load_before to manipulate the limit right before the collection is loaded:

public function setProductPaging(Varien_Event_Observer $observer) 
{
    $collection = $observer->getCollection();
    if ($collection->getCurPage() == 1) {
        $collection->setPageSize(22);
    } else {
        $productCollection->setPageSize(0);
        $productCollection->getSelect()->limit(20, 22 + 20 * ($collection->getCurPage() - 2));
    }
}

reference link: Show different number of products in category page

Thanks