Creating a custom filter in Drupal Views for yearly filtering

This snippet provides a custom Views filter for Drupal, enabling users to filter nodes by the year of their publication date. It adds a user-friendly dropdown in the Views UI, allowing easy selection of a year to filter content.

The hook_views_data() hook in Drupal is used to define how a module exposes database tables to Views.

/**
 * Implements hook_views_data().
 */
function MY_MODULE_views_data() {
  $data = [];

  $data['views']['year_filter'] = [
    'title' => t('Year filter - Custom Filter'),
    'filter' => [
      'title' => t('Year filter - Custom Filter'),
      'field' => 'created',
      'id' => 'year_filter',
    ],
  ];

  return $data;
}

To correctly implement your custom filter plugin in Drupal, you should place the code in the MY_MODULE/src/Plugin/views/filter directory. Below is an example of how your plugin code might look:

<?php

namespace Drupal\MY_MODULE\Plugin\views\filter;

use Drupal\Core\Form\FormStateInterface;
use Drupal\views\Plugin\views\filter\FilterPluginBase;

/**
 * Filters nodes by year of publish date.
 *
 * @ViewsFilter("year_filter")
 */
class YearFilter extends FilterPluginBase {

  /**
   * {@inheritdoc}
   */
  public function adminSummary() {
    return $this->t('Filters nodes by year of publish date.');
  }

  /**
   * {@inheritdoc}
   */
  protected function valueForm(&$form, FormStateInterface $form_state) {
    $current_year = date('Y');
    $options = [];

    for ($year = 2023; $year <= $current_year; $year++) {
      $options[$year] = $year;
    }

    $form['value'] = [
      '#type' => 'select',
      '#title' => $this->t('Year'),
      '#options' => $options,
      '#default_value' => $current_year,
    ];
  }

  /**
   * {@inheritdoc}
   */
  public function query() {
    $this->ensureMyTable();

    /** @var \Drupal\views\Plugin\views\query\Sql $query */
    $query = $this->query;

    if (!empty($this->value[0])) {
      $query->addWhereExpression(0, "EXTRACT(YEAR FROM FROM_UNIXTIME(node_field_data.created)) = :year", [':year' => $this->value[0]]);
    }
  }

}

Clear the caches after implementation, and then add the custom filter to a View used to display nodes.