Implement update hooks for node translation sets. Clean-up node translation sets.

Problem/Motivation

Other module can not react on node translation. Everything is done in form submit handler (see i18n_node_select_translation() / i18n_node_select_translation_submit()). There are not hooks. This is bad.

This is the current code for updating translation sets. There are no APIs involved, just a couple of queries.

  // ...

  $translations = $node->tnid ? translation_node_get_translations($node->tnid) : array($node->language => $node);
  foreach ($translations as $trans) {
    $current[$trans->language] = $trans->nid;
  }
  $update = array($node->language => $node->nid) + array_filter($form_state['values']['translations']['nid']);
  // Compute the difference to see which are the new translations and which ones to remove
  $new = array_diff_assoc($update, $current);
  $remove = array_diff_assoc($current, $update);

  // The tricky part: If the existing source is not in the new set, we need to create a new tnid
  if ($node->tnid && in_array($node->tnid, $update)) {
    $tnid = $node->tnid;
    $add = $new;
  }
  else {
    // Create new tnid, which is the source node
    $tnid = $node->nid;
    $add = $update;
  }
  // Now update values for all nodes
  if ($add) {
    db_update('node')
      ->fields(array(
        'tnid' => $tnid,
      ))
      ->condition('nid', $add)
      ->execute();
    if (count($new)) {
      drupal_set_message(format_plural(count($new), 'Added a node to the translation set.', 'Added @count nodes to the translation set.'));
    }
  }
  if ($remove) {
    db_update('node')
      ->fields(array(
        'tnid' => 0,
      ))
      ->condition('nid', $remove)
      ->execute();
    drupal_set_message(format_plural(count($remove), 'Removed a node from the translation set.', 'Removed @count nodes from the translation set.'));
  } 

  // ...

Proposed resolution

Refactoring i18n_node_select_translation_submit(). Decouple CRUD from form submission. Implement update hooks.

Remaining tasks

API Tests
Code

User interface changes

None.

API changes

API additions, wont affect existing modules.

Original report by [webflo]

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