How import Multilingual Content with Migrate Module

I would make 2 migrations, one for English and one for French. I would also set the French to be dependent on the English and then write a postImport() function on the French that makes translation sets. If anybody follows another pattern then I'd love to hear of it.

What would you like the result of the migration to be? If you want two nodes, an English node and a French node related in a translation set, then @rob_johnston's approach would be correct. If instead you want one node where the name field has an English value and a French value, it's a little trickier - you need to do some manipulation in prepareRow(), like:

$this->addFieldMapping('field_name', 'name');
$this->addFieldMapping('field_name:language', 'name_language');

public function prepareRow($row) {
  if (parent::prepareRow($row) === FALSE) {
    return FALSE;
  }
  // Assumes the source columns are english_name and french_name.
  $row->name = array($row->english_name, $row->french_name);
  $row->name_language = array('en', 'fr');

  return TRUE;
  }

I haven't done multilingual migration like this myself, so let me know if that doesn't work.

Well as a last word, I can confirm that works, but you'll need something like this too:

  function complete($entity, stdClass $row) {

    // Add a translation into the system only if it exists.
    if (!is_null($entity->title_field['fr'][0]['value'])) {

      // Create a record for the french translation in the entity translation table.
      $nid = db_insert('entity_translation')
             ->fields(array(
                      'entity_type' => 'node',
                      'entity_id' => $entity->nid,
                      'language' => 'fr',
                      'source' => $entity->language,
                      'uid' => $entity->uid,
                      'status' => $entity->status,
                      'translate' => $entity->translate,
                      'created' => $entity->created,
                      'changed' => $entity->changed,
                     ))
             ->execute();
    }
  }

@mikeryanIs this the way it should work in D8 too?

In Drupal 8 it seems the multilingual import is not really working yet as designed.
I ended up implementing the MigrateEvents::POST_ROW_SAVE Event.
Maybe someone will find a way to multilingual migrations using the following:

donkeymedia_migrate/donkeymedia_migrate.services.yml

services:
  donkeymedia_migrate.donkeymedia_migrate_post_save:
    class: Drupal\donkeymedia_migrate\EventSubscriber\DonkeymediaMigratePostSave
    tags:
      - { name: event_subscriber }

donkeymedia_migrate/src/EventSubscriber/DonkeymediaMigratePostSave.php

<?php
/**
 * Migrate post row save event subscriber and handler.
 */

namespace Drupal\donkeymedia_migrate\EventSubscriber;

// This is the interface we are going to implement.
use \Symfony\Component\EventDispatcher\EventSubscriberInterface;
use \Drupal\migrate\Event\MigrateEvents;
// This class contains the event we want to subscribe to.
use \Symfony\Component\HttpKernel\Event\GetResponseEvent;

/**
 * Subscribe to MigrateEvents::POST_ROW_SAVE events.
 */
class DonkeymediaMigratePostSave implements EventSubscriberInterface {

  /**
   * {@inheritdoc}
   *
   * Publish the Event.
   */
  public static function getSubscribedEvents() {
    $events[MigrateEvents::POST_ROW_SAVE][] = array('updateTranslations');
    return $events;
  }

  /**
   * MigrateEvents::POST_ROW_SAVE event handler.
   *
   * @param GetResponseEvent $event
   *   Instance of Symfony\Component\HttpKernel\Event\GetResponseEvent.
   */
  public function updateTranslations(GetResponseEvent $event) {

    module_load_include('inc', 'donkeymedia_migrate', 'qtranslate_parser');

    $row =  $event->getRow();

    // These are defined in migration.yml.
    $available_languages = $row->getSource()['constants']['available_languages'];
    $default_language = $row->getDestination()['langcode'];

    // Unset default language from available langguages.
    if (($key = array_search($default_language, $available_languages)) !== false) {
      unset($available_languages[$key]);
    }

    $migrate_src_values = $row->getSource();
    $migrate_dest_values = $row->getDestination();

    $migrated_node = $event->destinationIdValues[0];
    $entity = node_load($migrated_node);

    // Get multilingual fields in all languages.
    $titles = qtrans_split($migrate_src_values['title'], $available_languages);
    $body_values = qtrans_split($migrate_src_values['content:encoded'], $available_languages);

    foreach ($available_languages as $lang) {

      $values = array(
        // Non multilingual.
        'created' => $migrate_dest_values['created'],
        'uid' => $migrate_dest_values['uid'],
        'sticky' => $migrate_dest_values['sticky'],
        'status' => $migrate_dest_values['status'],

        // Multilingual.
        'title' => $titles[$lang],
        'body' => array(
          'value' => $body_values[$lang],
          'format' => $migrate_dest_values['body']['format'],
        ),
      );
      $translated_entity = $entity->addTranslation($lang, $values);
      $translated_entity->setChangedTime($migrate_dest_values['changed']);
      $translated_entity->save();
    }

    $map = $event->getMigration()->getIdMap();

    $map->saveIdMapping($event->getRow(), array($migrated_node));
  }

}

I know this is the kind of the wrong place to publish this, but repeatedly ended up here searching for solutions.

@digitaldonkey have you found a better way of doing it for Drupal 8?

edit: This is how core handles multilingual migrations for Drupal 8: https://www.drupal.org/node/2225775

@digitaldonkey what version of Drupal core did your code work with? I tried it on 8.1.7-dev and it caused some fatal errors, so then I tried with 8.0.0 and 8.0.1 and also no luck.