Get.php

<?php

namespace Drupal\migrate\Plugin\migrate\process;

use Drupal\migrate\Attribute\MigrateProcess;
use Drupal\migrate\ProcessPluginBase;
use Drupal\migrate\MigrateExecutableInterface;
use Drupal\migrate\Row;

/**
 * Gets the source value.
 *
 * Available configuration keys:
 * - source: Source property.
 *
 * The get plugin returns the value of the property given by the "source"
 * configuration key.
 *
 * Examples:
 *
 * @code
 * process:
 *   bar:
 *     plugin: get
 *     source: foo
 * @endcode
 *
 * This copies the source value of foo to the destination property "bar".
 *
 * Since get is the default process plugin, it can be shorthanded like this:
 *
 * @code
 * process:
 *   bar: foo
 * @endcode
 *
 * Get also supports a list of source properties.
 *
 * Example:
 *
 * @code
 * process:
 *   bar:
 *     plugin: get
 *     source:
 *       - foo1
 *       - foo2
 * @endcode
 *
 * This copies the array of source values [foo1, foo2] to the destination
 * property "bar".
 *
 * If the list of source properties contains an empty element then the current
 * value will be used. This makes it impossible to reach a source property with
 * an empty string as its name.
 *
 * Get also supports copying destination values. These are indicated by a
 * starting @ sign. Values using @ must be wrapped in quotes.
 *
 * @code
 * process:
 *   foo:
 *     plugin: machine_name
 *     source: baz
 *   bar:
 *     plugin: get
 *     source: '@foo'
 * @endcode
 *
 * This will simply copy the destination value of foo to the destination
 * property bar. foo configuration is included for illustration purposes.
 *
 * Because of this, if the source or destination property actually starts with a
 * "@", that character must be escaped with "@@". The referenced property
 * becomes, for example, "@@@foo".
 *
 * @code
 * process:
 *   '@foo':
 *     plugin: machine_name
 *     source: baz
 *   bar:
 *     plugin: get
 *     source: '@@@foo'
 * @endcode
 *
 * This should occur extremely rarely.
 *
 * @see \Drupal\migrate\Plugin\MigrateProcessInterface
 */
class Get extends ProcessPluginBase {
    
    /**
     * Flag indicating whether there are multiple values.
     *
     * @var bool
     */
    protected $multiple;
    
    /**
     * {@inheritdoc}
     */
    public function transform($value, MigrateExecutableInterface $migrate_executable, Row $row, $destination_property) {
        $source = $this->configuration['source'];
        $properties = is_string($source) ? [
            $source,
        ] : $source;
        $return = [];
        foreach ($properties as $property) {
            if ($property || (string) $property === '0') {
                $return[] = $row->get($property);
            }
            else {
                $return[] = $value;
            }
        }
        if (is_string($source)) {
            $this->multiple = is_array($return[0]);
            return $return[0];
        }
        return $return;
    }
    
    /**
     * {@inheritdoc}
     */
    public function multiple() {
        return $this->multiple;
    }

}