TaxonomyIndexTidDepth.php

<?php

namespace Drupal\taxonomy\Plugin\views\filter;

use Drupal\Core\Database\Database;
use Drupal\Core\Database\Query\Condition;
use Drupal\Core\Form\FormStateInterface;

/**
 * Filter handler for taxonomy terms with depth.
 *
 * This handler is actually part of the node table and has some restrictions,
 * because it uses a subquery to find nodes with.
 *
 * @ingroup views_filter_handlers
 *
 * @ViewsFilter("taxonomy_index_tid_depth")
 */
class TaxonomyIndexTidDepth extends TaxonomyIndexTid {
    public function operatorOptions($which = 'title') {
        return [
            'or' => $this->t('Is one of'),
        ];
    }
    protected function defineOptions() {
        $options = parent::defineOptions();
        $options['depth'] = [
            'default' => 0,
        ];
        return $options;
    }
    public function buildExtraOptionsForm(&$form, FormStateInterface $form_state) {
        parent::buildExtraOptionsForm($form, $form_state);
        $form['depth'] = [
            '#type' => 'weight',
            '#title' => $this->t('Depth'),
            '#default_value' => $this->options['depth'],
            '#description' => $this->t('The depth will match nodes tagged with terms in the hierarchy. For example, if you have the term "fruit" and a child term "apple", with a depth of 1 (or higher) then filtering for the term "fruit" will get nodes that are tagged with "apple" as well as "fruit". If negative, the reverse is true; searching for "apple" will also pick up nodes tagged with "fruit" if depth is -1 (or lower).'),
        ];
    }
    public function query() {
        // If no filter values are present, then do nothing.
        if (count($this->value) == 0) {
            return;
        }
        elseif (count($this->value) == 1) {
            // Sometimes $this->value is an array with a single element so convert it.
            if (is_array($this->value)) {
                $this->value = current($this->value);
            }
            $operator = '=';
        }
        else {
            $operator = 'IN';
        }
        // The normal use of ensureMyTable() here breaks Views.
        // So instead we trick the filter into using the alias of the base table.
        //   See https://www.drupal.org/node/271833.
        // If a relationship is set, we must use the alias it provides.
        if (!empty($this->relationship)) {
            $this->tableAlias = $this->relationship;
        }
        else {
            $this->tableAlias = $this->query
                ->ensureTable($this->view->storage
                ->get('base_table'));
        }
        // Now build the subqueries.
        $subquery = Database::getConnection()->select('taxonomy_index', 'tn');
        $subquery->addField('tn', 'nid');
        $where = (new Condition('OR'))->condition('tn.tid', $this->value, $operator);
        $last = "tn";
        if ($this->options['depth'] > 0) {
            $subquery->leftJoin('taxonomy_term__parent', 'th', "th.entity_id = tn.tid");
            $last = "th";
            foreach (range(1, abs($this->options['depth'])) as $count) {
                $subquery->leftJoin('taxonomy_term__parent', "th{$count}", "{$last}.parent_target_id = th{$count}.entity_id");
                $where->condition("th{$count}.entity_id", $this->value, $operator);
                $last = "th{$count}";
            }
        }
        elseif ($this->options['depth'] < 0) {
            foreach (range(1, abs($this->options['depth'])) as $count) {
                $field = $count == 1 ? 'tid' : 'entity_id';
                $subquery->leftJoin('taxonomy_term__parent', "th{$count}", "{$last}.{$field} = th{$count}.parent_target_id");
                $where->condition("th{$count}.entity_id", $this->value, $operator);
                $last = "th{$count}";
            }
        }
        $subquery->condition($where);
        $this->query
            ->addWhere($this->options['group'], "{$this->tableAlias}.{$this->realField}", $subquery, 'IN');
    }

}