Help with Magento 2.3 custom product sort plugin

Question

I have tried to implement a custom sorting plugin in Magento. Namely, with the options:

Price (Low > High)

Price (High > Low)

Name (A - Z)

Name (Z - A)

Now, I have the plugin installed and working, with code very similar to the examples in similar posts such as Magento 2 How to add custom sort by option.

Sorting by price works brilliantly, however, I'm struggling to get the correct join, in order to get the sorting by Name working. Take the code below in my plugins Toolbar.php

<?php
namespace Vendor\ModuleName\Plugin\Product\ProductList;

class Toolbar
{
    /**
    * Plugin
    *
    * @param \Magento\Catalog\Block\Product\ProductList\Toolbar $subject
    * @param \Closure $proceed
    * @param \Magento\Framework\Data\Collection $collection
    * @return \Magento\Catalog\Block\Product\ProductList\Toolbar
    */
    public function aroundSetCollection(
        \Magento\Catalog\Block\Product\ProductList\Toolbar $toolbar,
        \Closure $proceed,
        $collection
    ) {
        $this->_collection = $collection;
        $currentOrder = $toolbar->getCurrentOrder();
        $currentDirection = $toolbar->getCurrentDirection();
        $result = $proceed($collection);

        if ($currentOrder) {
            switch ($currentOrder) {

            case 'price_desc':
                $this->_collection
                    ->getSelect()
                    ->order('price_index.min_price DESC');
            break;

            case 'price_asc':
                $this->_collection
                    ->getSelect()
                    ->order('price_index.min_price ASC');
            break;

            case 'name_az':
                $this->_collection
                    ->getSelect()
                    ->order('e.name ASC');
            break;

            case 'name_za':
                $this->_collection
                    ->getSelect()
                    ->order('e.name DESC');
            break;

            default:        
                $this->_collection
                    ->setOrder($currentOrder, $currentDirection);
            break;

            }
        }

        return $result;
    }
}

As mentioned, sorting by price works fine, but when trying to sort by name, I get an error something along the lines of,

there is no column name on e

I understand that I need to perform a more complex join query to get the product name from the product_entity_varchar table but can't for the life of me seem to get it working or fully understand the syntax.

Some help would be much appreciated!

Answer 1

Use the setOrder method for sorting and pass the attribute name for a loaded attribute (e.g. name). This should work for you:

case 'name_az':
    $this->_collection
       ->setOrder('name', 'ASC');
break;

case 'name_za':
    $this->_collection
        ->setOrder('name', 'DESC');
break;