Custom transformer support

[dkarlovi]

(note: this includes #41 since it's not merged yet, but required for this to work)

This PR allows to add custom mappings to the ingested Elasticsearch documents, for example adding category images (which Coreshop supports, but VSF does not, AFAIK).

It works like this:

1. developer decorates the document mapper in their Pimcore services:

   AppBundle\VueStorefront\DocumentMapper\CategoryDocumentMapper:
       decorates: CoreShop2VueStorefrontBundle\Bridge\DocumentMapper\DocumentCategoryMapper

2. add AppBundle to ingested bundles for ES:

   ongr_elasticsearch:
   managers:
           mappings:
               - AppBundle

3. extend the existing document:

   
   namespace AppBundle\VueStorefront\Document;

use ONGR\ElasticsearchBundle\Annotation as ES;

/**

• @ES\Document() */ class Category extends \CoreShop2VueStorefrontBundle\Document\Category { /**

  • @ES\Property(type="keyword", name="image") */ public $image;

  public function setImage(?string $image): void { $this->image = $image; } }

  
  4. add the custom mapper (configured in 1):
  ```php
  namespace AppBundle\VueStorefront\DocumentMapper;

use AppBundle\VueStorefront\Document\Category; use CoreShop2VueStorefrontBundle\Bridge\DocumentMapperInterface; use Pimcore\Model\DataObject\ProductCategory;

class CategoryDocumentMapper implements DocumentMapperInterface { /**

• @var DocumentMapperInterface */ private $categoryMapper;

  public function __construct(DocumentMapperInterface $categoryMapper) { $this->categoryMapper = $categoryMapper; }

  public function supports($object): bool { return $this->categoryMapper->supports($object); }

  /**

• @param ProductCategory $object */ public function mapToDocument($object, ?string $language = null): Category { /* @var Category $document / $document = $this->toChildObject($this->categoryMapper->mapToDocument($object, $language), Category::class);

  // this part is custom
  if (null !== $image = $object->getImage()) {
      $document->setImage($image->getFullPath());
  }
  
  return $document;

  }

  private function toChildObject($object, $className) { return unserialize(sprintf( 'O:%d:"%s"%s', strlen($className), $className, strstr(strstr(serialize($object), '"'), ':') ), [$className]); } }