Magento 2: Filter Product Collection by Multiple Categories (Magento 2.1)

Question

I'm using Magento 2.1.0 and I'm currently having difficulties in filtering product collection with multiple categories. I've used more than a couple of ways to make it work but it won't.

Assuming:

$catalog_ids = [618, 619, 620];

1. Returns NULL

   $productCollection = $this->productCollectionFactory->create()
       ->addAttributeToSelect('*')
       ->addCategoriesFilter(array('in' => $catalog_ids));
   

2. Returns exception: Invalid attribute name: category_id

   $productCollection = $this->productCollectionFactory->create()
       ->addAttributeToSelect('*')
       ->addAttributeToFilter('category_id', array(
           'finset' => $catalog_ids
       ));
   

3. Returns Syntax error or access violation

   $productCollection = $this->productCollectionFactory->create()
       ->addAttributeToSelect('*')
       ->addAttributeToFilter('category_ids', array(
           'finset' => $catalog_ids
       ));
   

Any advice on how I could be able to have this work or have something link this work?

Answer 1

You are probably used to the "every method returns $this" paradigm from Magento 1. This is not the case anymore (at least not always).

Specifically, addCategoriesFilter() does not return anything and that's why you get null.

Change the code to:

$productCollection = $this->productCollectionFactory->create();
$productCollection->addAttributeToSelect('*');
$productCollection->addCategoriesFilter(array('in' => $catalog_ids));

Answer 2

Your first try is definitely the right way of doing it:

$values = [318, 619, 620];
$conditionType = "in";
$productCollection->addCategoriesFilter([$conditionType => $values]);

Now there's two things to ensure: $productCollection must be an instance of Magento\Catalog\Model\ResourceModel\Product\Collection for this to work (or from a class that extends it).

And obviously you need to have products in the catalog_category_product table that matches that condition, maybe that's not the case and that's why you get NULL.