class Flatten

Flattens the source value.

The flatten process plugin converts a nested array into a flat array. For example [[1, 2, [3, 4]], [5], 6] becomes [1, 2, 3, 4, 5, 6]. During some types of processing (e.g. user permission splitting), what was once a one-dimensional array gets transformed into a multidimensional array. This plugin will flatten them back down to one-dimensional arrays again.

Example:

process:
  tags:
     -
       plugin: default_value
       source: foo
       default_value: [bar, [alpha, beta]]
     -
       plugin: flatten

In this example, the default_value process returns [bar, [alpha, beta]] (given a NULL value of foo). At this point, Migrate would try to import two items: bar and [alpha, beta]. The latter is not a valid one and won't be imported. We need to pass the values through the flatten processor to obtain a three items array [bar, alpha, beta], suitable for import.

Plugin annotation

@MigrateProcessPlugin(
  id = "flatten",
  handle_multiples = TRUE
)

Hierarchy

• class \Drupal\Component\Plugin\PluginBase implements \Drupal\Component\Plugin\PluginInspectionInterface, \Drupal\Component\Plugin\DerivativeInspectionInterface
  • class \Drupal\Core\Plugin\PluginBase extends \Drupal\Component\Plugin\PluginBase uses \Drupal\Core\StringTranslation\StringTranslationTrait, \Drupal\Core\DependencyInjection\DependencySerializationTrait, \Drupal\Core\Messenger\MessengerTrait
    • class \Drupal\migrate\ProcessPluginBase extends \Drupal\Core\Plugin\PluginBase implements \Drupal\migrate\Plugin\MigrateProcessInterface
      • class \Drupal\migrate\Plugin\migrate\process\Flatten extends \Drupal\migrate\ProcessPluginBase

Expanded class hierarchy of Flatten

See also

\Drupal\migrate\Plugin\MigrateProcessInterface

File

core/modules/migrate/src/Plugin/migrate/process/Flatten.php, line 45

Namespace

class Flatten extends ProcessPluginBase {
    
    /**
     * Flatten nested array values to single array values.
     *
     * For example, [[1, 2, [3, 4]]] becomes [1, 2, 3, 4].
     */
    public function transform($value, MigrateExecutableInterface $migrate_executable, Row $row, $destination_property) {
        if (!is_array($value) && !is_object($value)) {
            $type = gettype($value);
            throw new MigrateException(sprintf("Input should be an array or an object, instead it was of type '%s'", $type));
        }
        return iterator_to_array(new \RecursiveIteratorIterator(new \RecursiveArrayIterator($value)), FALSE);
    }

}

Members