How to programatically update a field for a revision?

Question

What is wrong with this approach for updating a field value in a specific revision:

public function myTest() {

  $test = 'mytest33';

  $node_revision = \Drupal::entityTypeManager()
    ->getStorage('node')
    ->loadRevision(10364);

  $node_revision->set('field_my_field', $test);
  $node_revision->save();

  return [
    '#markup' => 'Test page.',
  ];
}

When I load this simple test page and look at revision 10364 for the node, field_my_field doesn't update.

Answer 1

I needed to use the setSyncing method, like so:

public function myTest() {

  $test = 'mytest33';

  $node_revision = \Drupal::entityTypeManager()
    ->getStorage('node')
    ->loadRevision(10364);

  // See https://www.drupal.org/project/drupal/issues/2859042#comment-13083066
  $node_revision->original = \Drupal::entityTypeManager()
    ->getStorage('node')
    ->loadRevision(10364);

  // See https://www.drupal.org/project/drupal/issues/3335119
  $node_revision->setSyncing(TRUE);

  $node_revision->set('field_my_field', $test);
  $node_revision->save();

  return [
    '#markup' => 'Test page.',
  ];
}