Filter on joined columns in a collectionGridProcessor doesn't work for EAV collections

[Vinai]

EAV Collections expect columns to be declared as attributes. Joined columns are not available as attributes.

More information can be found in #55.

Test to reproduce the issue:

/**
 * @magentoDataFixture Magento/Catalog/_files/product_simple.php
 * @magentoDataFixture Magento/Catalog/_files/products_list.php
 */
public function testFilterJoinedAttributeOnEavCollection(): void
{
    $processor = new class() extends AbstractGridSourceProcessor implements HyvaGridCollectionProcessorInterface {

        /**
         * @param ProductCollection $source
         * @param string $gridName
         */
        public function afterInitSelect(AbstractDbCollection $source, string $gridName): void
        {
            $source->joinField(
                'test_field',
                'catalog_category_product',
                'product_id',
                'e.entity_id = test_field'
            );
        }
    };

    $args = [
        'gridName'            => 'test',
        'processors'          => [$processor],
        'sourceConfiguration' => ['collection' => ProductCollection::class],
    ];
    /** @var CollectionGridSourceType $sut */
    $sut = ObjectManager::getInstance()->create(CollectionGridSourceType::class, $args);

    /** @var SearchCriteriaBuilder $searchCriteriaBuilder */
    $searchCriteriaBuilder = ObjectManager::getInstance()->get(SearchCriteriaBuilder::class);
    $searchCriteriaBuilder->addFilter('test_field', '1');

    $rawGridData = $sut->fetchData($searchCriteriaBuilder->create());
    $records = $sut->extractRecords($rawGridData);
    $this->assertGreaterThan(0, count($records));
}

[natedawg92]

I came across this issue yesterday whilst implementing a grid using a custom Grid Collection.

I was able to work around this issue by adding fake method docBlocks to the Model class for the joined fields and/or custom fields e.g.

/**
 * @method ?string getProductSku()
 * @method ?string getProductName()
 * @method ?string getCustomerGroupCode()
 * @method ?\Vendor\TradeAccounts\Model\StoreTierPriceValue getValueObject()
 */

This isn't really ideal as the model doesn't really have these functions and will only work if you control the Model Source code