Export UI, Features and Taxonomy

Here's a quicky. Let's say you've created some exportable content (using CTools) which references a term ID and you have to go from your dev site to the production site. And your taxonomy is also being exported using UUID.

Somehow you have to tie them together because sure as eggs is eggs the term IDs created on the production site are not going to be the same as the local ones. That's why you used UUID in the first place. Right?

Here's what you do: in your local exportable you will have a column for the term ID so include a column for the term UUID as well.

In your add/edit form for the exportable you'll have to include some code to automatically add the selected term's UUID - I did it in the form validation. Basically you read the selected term ID, load the selected term which will have the UUID in it (because it's added to the base table). Set the term UUID value in $form_state['values']. Assuming you're using CTools Export UI the UUID will be saved automatically.

Also, in the module install, add "no export" => TRUE to the TID field, so that Export UI does not include it in the feature. (This code works for Features, it doesn't work for single imports, I'll leave that as an exercise for the reader - hint: you can specify an "import callback".)

That's the easy bit, when you export your content it will be saved with the term's UUID and not the term's ID. The difficult bit is how to link the UUID of exported content when Features loads it into the new site.

Except it's not hard at all. In your export specification, in the schema, you have the "default hook", well CTools Export UI very kindly calls an drupal_alter() on the default items after it's loaded them. So we can do this:

/**
 * Implements hook_DEFAULT_HOOK_alter().
 *
 * This intercepts any defaults picked up from code and converts
 * their UUID category into the local TID (which might be different
 * on every site).
 *
 */
function mymodule_my_default_hook_alter(&$items) {
  $uuids = db_select('taxonomy_term_data', 't')
      ->fields('t', array('uuid', 'tid'))
      ->execute()->fetchAllKeyed();

  foreach ($items as $item) {
    if (empty($item->tid) && !empty($uuids[$item->uuid])) {
      $item->tid= $uuids[$item->uuid];
    }
  }
}

The database call creates an array which maps all UUIDs to TIDs in one go. If your site uses a lot of taxonomy terms - perhaps you have user tagging - you might want to restrict this call to a specific vocabulary.

The exact item property names will depend on what you set up in your schema.

Sorted.