Programmatically override a metatag when generating a node

Lets document this properly for both branches.

So, lets look at the basics:

https://gaiaes.com/article/create-a-node-programmatically-drupal-8

$values = array(
  'nid' => NULL,
  'type' => 'article',
  'title' => 'Create node using Node storage create method',
  'uid' => 1,
  'status' => TRUE,
);
$node = \Drupal::entityManager()->getStorage('node')->create($values);
$node->save();

entityManager() was replaced with entityTypeManager(), so it should be:

$entity_type = 'node';
$values = [
  'nid' => NULL,
  'type' => 'article',
  'title' => 'Create node using Node storage create method',
  'uid' => 1,
  'status' => TRUE,
];
$node = \Drupal::entityTypeManager()->getStorage($entity_type)->create($values);
$node->save();

I wonder would this work?

$entity_type = 'node';
$values = [
  'nid' => NULL,
  'type' => 'article',
  'title' => 'Testing metatag creation',
  'uid' => 1,
  'status' => TRUE,
  'field_metatags' => [
    'x-default' => [
      'value' => serialize([
        'title' => 'Some title',
        'description' => 'Some description.',
      ]),
    ],
  ],
];
$node = \Drupal::entityTypeManager()->getStorage($entity_type)->create($values);
$node->save();

I will give your last comment a try today.

Well, given your example i found that all i needed to do was serialize the data, but you dont have to add it to x-default, you can just assign it to the field like so.

$entity_type = 'node';
$values = [
  'nid' => NULL,
  'type' => 'article',
  'title' => 'Testing metatag creation',
  'uid' => 1,
  'status' => TRUE,
  'field_metatags' => serialize([
        'title' => 'Some title',
        'description' => 'Some description.',
      ]),
];
$node = \Drupal::entityTypeManager()->getStorage($entity_type)->create($values);
$node->save();

@haynescw: Awesome, thanks for testing that and working out the correct structure.

@nixvan: Great, thanks!

Additions to the README.txt would be the best step, for now.

Documentation can go in 1.0.

Some improvements.

Committed. Thanks, nicxvan!

please see this article for dynamically adding metatags.