Migrate Add Field Collection

MigrationClass.php

<?php
/**
   * Attaches a (group) of field collections to an node entity
   *
   * @param stdClass $node_entity The loaded node object.
   * @param array $field_collections the array of structures describing the entity collections
   *                keyed by the entity collection field name.
   * @return void
   */
  public function attachFieldCollections(&$node_entity, $field_collections)
  {
    $last_changed = $node_entity->changed;
    
    foreach ($field_collections as $field_coll_name => $field_collection_group) {
      for ($i=0; $i < count($field_collection_group); $i++) { 
        $field_coll_fields = $field_collection_group[$i];
        
        $field_c = entity_create('field_collection_item', array('field_name' => $field_coll_name));
        $field_c->setHostEntity('node', $node_entity);
    
        $field_collection_w = entity_metadata_wrapper('field_collection_item', $field_c);
    
        foreach ($field_coll_fields as $subfield_name => $subfield_value) {
          $field_collection_w->{$subfield_name}->set( $subfield_value );
        }
    
        $field_collection_w->save();
      }
    }
    
    // Save the changes on the node and restore the last changed time to the original
    node_save($node_entity);
    self::setNodeChanged($node_entity->nid, $last_changed);
  }
  
  public static function setNodeChanged($nid, $changed)
  {
    $query = db_update('node')
      ->fields(array( 'changed' => $changed ))
        ->condition('nid', $entity->nid, '=');
    
    @$query->execute();
  }
?>


To use it you need to byuld an array with this structure:
<?php
$someArray = array(
  'field_collection_name' => array( // field_collection_name is the actual (machine) name of the field collection
    array(
      'field_name' => 'some to give value' // field_name is tha name of a field inside a field collection
      'field_some_file' => array('fid'=>$file_id) // you can passa also "complex types"
    ),
  ),
  // ecc...
);

?>

Example #1:
<?php

$field_collections['field_main_image'] = array(
  array(
    'field_image' => array('fid' => $migrated_file_id),
    'field_image_caption' => $caption,
    ),
);
$this->attachFieldCollections($entity, $field_collections);

?>

To attach more items of one field collection type:
<?php

$field_collections['field_blockquote'] = array(
  array(
    'field_quote_title' => $first_quote_title,
    'field_quote_content' => $first_quote_text,
    ),
  array(
    'field_quote_title' => $second_quote_title,
    'field_quote_content' => $second_quote_text,
    ),
);

// OR also

$field_collections['field_blockquote'] = array();

// later on in a loop (for/foreach/whatever)
$field_collections['field_blockquote'][] = array(
  'field_quote_title' => $quote_title,
  'field_quote_content' => $quote_content,
);

$this->attachFieldCollections($entity, $field_collections);
?>


Another option is to add multiple field collections to different fields, also easy:
<?php

$field_collections['field_main_image'] = array(
  array(
    'field_image' => array('fid' => $migrated_file_id),
    'field_image_caption' => $caption,
    ),
);

$field_collections['field_blockquote'] = array(
  array(
    'field_quote_title' => $first_quote_title,
    'field_quote_content' => $first_quote_text,
    ),
  array(
    'field_quote_title' => $second_quote_title,
    'field_quote_content' => $second_quote_text,
    ),
);

$this->attachFieldCollections($entity, $field_collections);

?>