August 3, 2017
In this post I will show a custom process plugin that I created to migrate taxonomy terms. The plugin handles the creation of new terms and prevents duplicates.
Below is a portion of the migration template. In the example, I am migrating new terms into keywords vocabulary via field_keywords field.
field_keywords:
-
plugin: existing_term
# Destination (Drupal) vocabulary name
vocabulary: keywords
# Source query should return term name
source: term_name
-
plugin: skip_on_empty
method: row
This is the source code for the process plugin.
<?php
namespace Drupal\my_module\Plugin\migrate\process;
use Drupal\migrate\ProcessPluginBase;
use Drupal\migrate\MigrateExecutableInterface;
use Drupal\migrate\MigrateSkipProcessException;
use Drupal\migrate\Row;
use Drupal\taxonomy\Entity\Term;
/**
* Check if term exists and create new if doesn't.
*
* @MigrateProcessPlugin(
* id = "existing_term"
* )
*/
class ExistingTerm extends ProcessPluginBase {
/**
* {@inheritdoc}
*/
public function transform($term_name, MigrateExecutableInterface $migrate_executable, Row $row, $destination_property) {
$vocabulary = $this->configuration['vocabulary'];
if (empty($term_name)) {
throw new MigrateSkipProcessException();
}
if ($tid = $this->getTidByName($term_name, $vocabulary)) {
$term = Term::load($tid);
}
else {
$term = Term::create([
'name' => $term_name,
'vid' => $vocabulary,
])->save();
if ($tid = $this->getTidByName($term_name, $vocabulary)) {
$term = Term::load($tid);
}
}
return [
'target_id' => is_object($term) ? $term->id() : 0,
];
}
/**
* Load term by name.
*/
protected function getTidByName($name = NULL, $vocabulary = NULL) {
$properties = [];
if (!empty($name)) {
$properties['name'] = $name;
}
if (!empty($vocabulary)) {
$properties['vid'] = $vocabulary;
}
$terms = \Drupal::entityManager()->getStorage('taxonomy_term')->loadByProperties($properties);
$term = reset($terms);
return !empty($term) ? $term->id() : 0;
}
}
The logic of the plugin is very simple. Please let me know in comments or questions. Also, please share any problems you've had during your content migrations and how you solved them.
