How to migrate taxonomy with hierarchy?

Question

I'm trying to create a hierarchical taxonomy from a perpared migration database table which looks like that:

ID | NAME | PARENT
------------------
 0 | FOO  |       
 1 | BAR  |       
 2 | LORE | FOO
 3 | IPSE | FOO
 4 | DOLO | BAR

It's a pretty messy data structure, but fact is there are parent and child terms in one table.

What I did so far is migrating the parent terms first. Now my custom taxonomy looks like this:

_
|_ FOO
|_ BAR

The migration code snipped I used to achieve this works like that:

$this->addFieldMapping('name', 'PARENT');

Until now everything works as expected!

---

Now, in a second migration step I want to add the child terms like that to my taxonomy:

_
|_ FOO
  |_ LORE
  |_ IPSE
|_ BAR
  |_ DOLO

What I tried is to add a hierarchical mapping to my migration:

$this->addFieldMapping('name', 'NAME');
$this->addFieldMapping('parent_name', 'PARENT')
    ->arguments(array('source_type' => 'name'));

But this does not work, the result is an unhierarchical list like that:

_
|_ FOO
|_ LORE
|_ IPSE
|_ BAR
|_ DOLO

Did anyone try to do something like this before? Any ideas? Thanks!

Answer 1

I had to migrate a nested Vocabulary from Drupal 6 to Drupal 7. My Strategy was:

1. Migrate the plain terms

2. Use the postImport() of Migrate-API to map the Parent-Relationship

   public function postImport() {
   
   // Get alle Terms from features_dd_private_contact_form_subjects
   // Query zum Laden der Daten aus Drupal6
   $source_query = Database::getConnection('legacy', 'legacy')
     ->select('term_data', 't');
   
   // Join Terms with voab
   $source_query->join('vocabulary', 'v', 'v.vid = t.vid');
   
   // Join Hierarchy
   $source_query->join('term_hierarchy', 'th', 'th.tid = t.tid');
   
   $source_query->condition('th.parent', '0', '<>');
   
   $source_query->fields('th', array());
   
   $source_query->condition(
     'v.module',
     'features_dd_private_contact_form_subjects',
     '='
   );
   
   $source_query->fields('t');
   
   $source_records = $source_query->execute();
   
   foreach ($source_records as $source_record) {
   
   
     // Term-ID in destination db.
     $dest_tid = $this->get_destination_tid_by_old_tid($source_record->tid);
   
   
     // Parent-Tid in the destination.
     $dest_parent_tid = $this->get_destination_tid_by_old_tid($source_record->parent);
   
     $child_term = taxonomy_term_load($dest_tid);
     $child_term->parent = $dest_parent_tid;
     taxonomy_term_save($child_term);
   }
   

   }