Adding custom operations with hook_entity_operation()

Question

I'm trying to add a custom entity operation to taxonomy terms of a specific vocabulary.

I've found documentation on using hook_entity_operation() to add the operation, and that works, but I'm not sure what to do from there.

Here's the hook implementation:

function nm_target_entity_operation(\Drupal\Core\Entity\EntityInterface $entity) {
  $operations = [];
  if ($entity->getEntityTypeId() == 'taxonomy_term' && $entity->vid->getString() == 'data-source') {
    $operations['import'] = [
      'title' => t('Re-import'),
      'url' => // what goes here?
      'weight' => 50,
    ];
  }
  return $operations;
}

If I want to have a confirmation page at /taxonomy/term/{taxonomy_term}/import, what do I put in the URL property and what kind of class should that route point at?

I took a look at Entity Clone module as that's the only contribute module we use that implements that hook, but that does complicated things with link templates that I don't understand.

Answer 1

The explanation of what the array returned by hook_entity_operation() contains is explained in the documentation for EntityListBuilderInterface::getOperations().

• title: The localized title of the operation.
• url: An instance of \Drupal\Core\Url for the operation URL.
• weight: The weight of this operation.

'url' is simply the URL for the page executing that operation.

There are 5 implementations of that hook done in Drupal core, for example config_translation_entity_operation(), content_translation_entity_operation(), or field_ui_entity_operation().
The code they use to get the URL vary from one implementation to the other. The simpler way to get a URL for a page created from a module you wrote, for which you know the page route, is calling Url::fromRoute().