EC-CUBE4でタグIDによる商品の絞り込みができるようにする方法

<?php

namespace Customize\Form\Extension;

use Eccube\Form\Type\SearchProductType;
use Symfony\Component\Form\AbstractTypeExtension;
use Symfony\Component\Form\Extension\Core\Type\HiddenType;
use Symfony\Component\Form\FormBuilderInterface;

class SearchProductTypeExtension extends AbstractTypeExtension {
  /**
   * {@inheritdoc}
   */
  public function buildForm(FormBuilderInterface $builder, array $options) {
    $builder->add('tag_id', HiddenType::class, []);
  }

  /**
   * {@inheritdoc}
   */
  public function getExtendedType() {
    return SearchProductType::class;
  }
}

<?php

namespace Customize\Repository;

use Eccube\Doctrine\Query\QueryCustomizer;
use Eccube\Repository\QueryKey;
use Doctrine\ORM\QueryBuilder;

class TagIdSearchCustomizer implements QueryCustomizer {

  public function customize(QueryBuilder $builder, $params, $queryKey) {
    if (!empty($params['tag_id']) && $params['tag_id']) {
      $builder->innerJoin('p.ProductTag', 'pt');
      $builder->andWhere('pt.Tag = :tag_id');
      $builder->setParameter('tag_id', $params['tag_id']);
    }
  }

  public function getQueryKey(): string {
    return QueryKey::PRODUCT_SEARCH;
  }
}

https://example.com/products/list?tag_id=1

{% set Tags = repository('Eccube\\Entity\\Tag').getList() %}
{% set now_tag_id = app.request.query.get('tag_id') %}
{% if now_tag_id is not null %}
  {% for Tag in Tags %}
    {% if now_tag_id == Tag.id %}
      <li class="ec-topicpath__divider">/</li>
      <li class="ec-topicpath__item"><a href="{{ url('product_list') }}?tag_id={{ Tag.id }}">{{ Tag.name }}</a></li>
    {% endif %}
  {% endfor %}
{% endif %}

<div class="ec-searchnavRole__topicpath">
  <ol class="ec-topicpath">
    <li class="ec-topicpath__item"><a href="{{ url('product_list') }}">{{ '全て'|trans }}</a>
    </li>
    {% set Tags = repository('Eccube\\Entity\\Tag').getList() %}
    {% set now_tag_id = app.request.query.get('tag_id') %}
    {% if now_tag_id is not null %}
      {% for Tag in Tags %}
        {% if now_tag_id == Tag.id %}
          <li class="ec-topicpath__divider">/</li>
          <li class="ec-topicpath__item"><a href="{{ url('product_list') }}?tag_id={{ Tag.id }}">{{ Tag.name }}</a></li>
        {% endif %}
      {% endfor %}
    {% endif %}
    {% if Category is not null %}
      {% for Path in Category.path %}
        <li class="ec-topicpath__divider">|</li>
        <li class="ec-topicpath__item{% if loop.last %}--active{% endif %}"><a href="{{ url('product_list') }}?category_id={{ Path.id }}">{{ Path.name }}</a>
        </li>
      {% endfor %}
    {% endif %}
    {% if search_form.vars.value and search_form.vars.value.name %}
      <li class="ec-topicpath__divider">|</li>
      <li class="ec-topicpath__item">{{ '「%name%」の検索結果'|trans({ '%name%': search_form.vars.value.name }) }}</li>
    {% endif %}
  </ol>
</div>

{% if Product.Tags is not empty %}
<ul class="ec-productRole__tags">
  {% for Tag in Product.Tags %}
    <li class="ec-productRole__tag tag_{{ Tag.id }}">
      <a href="{{ url('product_list') }}?tag_id={{ Tag.id }}">{{ Tag }}</a>
    </li>
  {% endfor %}
</ul>
{% endif %}