Migrate/Migrated2d: Linking Migrated Nodes to Non-migrated Terms

Migrate and Migrate d2d modules expose a powerful API to developers who have the task to migrate a part or an entire website to Drupal 7.

The approach:

1. Identifying unmigrated terms that are mapped to the node
2. Unlinking the node and the terms before the node migration
3. Saving the IDs of the terms in a static variable
4. Relinking the node and the terms right after persisting the node

Note that prepareRow() and complete() belong to the migration base classes; prepareRow() is called very early in the process before importing each node and complete() is called right after persisting each node.

public function prepareRow($row) {
  if (parent::prepareRow($row) === FALSE) {
    return FALSE;
  }
  // remove unmigrated tags from $row
  $row = $this->rm_unmigrated_terms(...);
}

function complete($node, stdClass $row) {
  // linking node to unmigrated terms in target
  $this->linking_stories_to_unmigrated_terms(...);
}

For more information regarding the migrate/migrated2d API, click here.