RevisionLink.php

<?php

/**
 * @file
 * Definition of Drupal\node\Plugin\views\field\RevisionLink.
 */
namespace Drupal\node\Plugin\views\field;

use Drupal\node\Plugin\views\field\Link;
use Drupal\views\ViewExecutable;
use Drupal\Core\Annotation\Plugin;

/**
 * Field handler to present a link to a node revision.
 *
 * @ingroup views_field_handlers
 *
 * @Plugin(
 *   id = "node_revision_link",
 *   module = "node"
 * )
 */
class RevisionLink extends Link {

  /**
   * Overrides Drupal\views\Plugin\views\field\FieldPluginBase::init().
   */
  public function init(ViewExecutable $view, &$options) {
    parent::init($view, $options);
    $this->additional_fields['node_vid'] = array(
      'table' => 'node_revision',
      'field' => 'vid',
    );
  }
  public function access() {
    return user_access('view revisions') || user_access('administer nodes');
  }
  function render_link($data, $values) {
    list($node, $vid) = $this
      ->get_revision_entity($values, 'view');
    if (!isset($vid)) {
      return;
    }

    // Current revision uses the node view path.
    $path = 'node/' . $node->nid;
    if ($node->vid != $vid) {
      $path .= "/revisions/{$vid}/view";
    }
    $this->options['alter']['make_link'] = TRUE;
    $this->options['alter']['path'] = $path;
    $this->options['alter']['query'] = drupal_get_destination();
    return !empty($this->options['text']) ? $this->options['text'] : t('view');
  }

  /**
   * Returns the revision values of a node.
   *
   * @param object $values
   *   An object containing all retrieved values.
   * @param string $op
   *   The operation being performed.
   *
   * @return array
   *   A numerically indexed array containing the current node object and the
   *   revision ID for this row.
   */
  function get_revision_entity($values, $op) {
    $vid = $this
      ->get_value($values, 'node_vid');
    $node = $this
      ->get_value($values);

    // Unpublished nodes ignore access control.
    $node->status = 1;

    // Ensure user has access to perform the operation on this node.
    if (!node_access($op, $node)) {
      return array(
        $node,
        NULL,
      );
    }
    return array(
      $node,
      $vid,
    );
  }

}