Magento 2 - Category list query

Question

I've got a module in magento 1 - it stops certain products being listed depending upon a set of attributes.

For example if the user logs in and an customer attribute set with a value of 100, they would see all products with an attribute called "test" with the value of 100 and no others...

I'm looking at porting this functionality accross to magento 2, I was hoping for some pointers on where magento 2 does the category listing...

In magento 1 I extend the mage/catalog/model/category and add an addattributetofilter... along with a few others things...

Looking breifly at magento 2, I thought that I'd be able to duplicate the behaviour by overwriting/extending CollectionFilter in the namespace 'Magento\Catalog\Model\Layer\Category' yet anything I do here results in no results regardless of what I do.

Any tips/help would be great at the minute.

Answer 1

It is best to avoid overwriting/extending core classes because this introduces conflicts between extensions. You can add custom filter to product collection by adding observer on catalog_product_collection_load_before event.

Declare your observer, create MyModule/etc/frontend/events.xml with the following content

<?xml version="1.0"?>
<config xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="urn:magento:framework:Event/etc/events.xsd">
    <event name="catalog_product_collection_load_before">
        <observer name="add-filter-to-product-collection-observer" instance="MyCompany\MyModule\Observer\AddFilterToProductCollectionObserver"/>
    </event>
</config>

Create observer MyModule\Observer\AddFilterToProductCollectionObserver.php

<?php
namespace MyCompany\MyModule\Observer;

use Magento\Framework\Event\ObserverInterface;
use Magento\Framework\Event\Observer as EventObserver;

class AddStockStatusToCollectionObserver implements ObserverInterface
{
    /**
     * Add filter to product collection
     *
     * @param EventObserver $observer
     * @return void
     */
    public function execute(EventObserver $observer)
    {
        $productCollection = $observer->getEvent()->getCollection();
        $productCollection->addAttributeToFilter('my_attribute', 'value');
    }
}

Hope this will lead you in right direction.