Magento 2: Display out of stock items in the end in API

Question

I am using a headless magento 2 approach for my store. I have made an API which accepts parameters like:

category_slug, sort_by, sort_order, page_size, current_page

and returns the products matching the criteria.

Now the issue I am facing is, I want the out of stock products to be pushed down at the end of the ENTIRE collection.

My code is below:

$categoryProducts = $productFactory->create()
                        ->addAttributeToSelect('*')
                        ->addCategoriesFilter(array('in' => $categoryList))
                        ->addAttributeToFilter('status',1)
                        ->addAttributeToFilter('visibility',4)
                        ->addAttributeToSort($sort_by, $sort_order)
                        ->addAttributeToSort('is_in_stock', 'DESC')
                        ->setPageSize($page_size)
                        ->setCurPage($current_page)
                        ->load();

is_in_stock is a custom attribute I created which automatically gets set to 0 or 1 (0 being out of stock and 1 being in-stock), whenever a change in stock is detected (did this using an observer, working fine).

Now, suppose I want to sort the collection on PRICE, in ASC order the collection I am getting after this would look something like:

In-stock items of 10$, Out of stock items of 10$, In-stock items of 15$, Out of stock items of 15$, in stock items of 20$, and so on...

But what I want is:

In-stock items of 10$, In-stock items of 15$, in stock items of 20$, Out of stock items of 10$, Out of stock items of 15$, and so on...

I feel it's something really small and stupid that I am missing. any help would be appreciated.

Thanks!

Answer 1

I'm assuming here that ->addAttributeToSort($sort_by, $sort_order) is your price sort.

Sounds like you just need to swap your sort conditions. Since currently you will get is sorted by PRICE first, then STOCK.

So instead of

->addAttributeToSort($sort_by, $sort_order)
->addAttributeToSort('is_in_stock', 'DESC')

Change the order to

->addAttributeToSort('is_in_stock', 'DESC')
->addAttributeToSort($sort_by, $sort_order)

Now you'll first get all in-stock items, sorted by your second condition (price). Followed by all out-of-stock items, sorted by -again- your second condition (price).