Diff between two different entities

7.x-3.x introduced support for diffs between different nodes. Please reopen if problem persists in 7.x-3.x branch.

No direct comparison was included. Can you let me know how you were doing this please?

It may point to an unknown bug within the code although at this stage I think it is a GIGO bug...

Interested in this one aswell. Can you please provide an example of how to diff between 2 entities.
Thanks.

I am writing a administrative logging module and I'm needing entity diff's for the logs too.

This first patch abstracts out the logic from _diff_body_rows() into diff_entity_body_rows(). This has most of the logic for the UI and internally calls diff_compare_entities() for the actual comparison. This function does not cover the header row.

I'm using a custom CTool plugin that calls this to render the diff as a string for insertion into the log.

class EntityCRUDLogOperation extends LogOperation {
  function logUpdate($entity_type, $entity) {
    $original = empty($entity->original) || !is_object($entity->original) ? entity_load_unchanged($entity_type, $entity) : $entity->original;
    $diff_html = $this->diffEntity($entity_type, $original, $entity);
  }

  function diffEntity($entity_type, $entity_one, $entity_two) {
    if (!module_exists('diff')) {
      return '';
    }

    switch ($entity_type) {
      case 'node':
        $old_header = t('<strong>@title</strong><br />!date by !username', array(
          '@title' => $entity_one->title,
          '!date' => l(format_date($entity_one->created), "node/$entity_one->nid"),
          '!username' => theme('username', array('account' => user_load($entity_one->uid))),
        ));
        $new_header = t('<strong>@title</strong><br />!date by !username', array(
          '@title' => $entity_two->title,
          '!date' => l(format_date($entity_two->created), "node/$entity_two->nid"),
          '!username' => theme('username', array('account' => user_load($entity_two->uid))),
        ));
        break;

      default:
        $old_header = '<strong>' . entity_label($entity_type, $entity_one) . '</strong>';
        $new_header = '<strong>' . entity_label($entity_type, $entity_two) . '</strong>';
        break;
    }

    module_load_include('pages.inc', 'diff');
    $header = _diff_default_header($old_header, $new_header);
    $rows = diff_entity_body_rows($entity_type, $entity_one, $entity_two);

    $build['diff_table'] = array(
      '#theme' => 'table',
      '#header' => $header,
      '#rows' => $rows,
      '#attributes' => array('class' => array('diff')),
      '#colgroups' => _diff_default_cols(),
      '#sticky' => FALSE,
    );

    return drupal_render($build);
  }
}

A smaller example for user entities (should work without #2110371: Providing User entity support) but requires the above patch.

$account_a = user_load(1);
$account_b = user_load(5);
module_load_include('pages.inc', 'diff');
$header = _diff_default_header(entity_label('user', $account_a), entity_label('user', $account_b));
$rows = diff_entity_body_rows('user', $account_a, $account_b);

$build['diff_table'] = array(
  '#theme' => 'table',
  '#header' => $header,
  '#rows' => $rows,
  '#attributes' => array('class' => array('diff')),
  '#colgroups' => _diff_default_cols(),
  '#sticky' => FALSE,
);

print drupal_render($build['diff_table']);

Added in cdee341