Migration into multi-value field collection

Question

I am attempting to use the patch in comment #222 of this issue (https://drupal.org/node/1175082#comment-7625869) to migrate data into a multi-value field collection.

I create an array of the objects in prepareRow() but when the migration completes and I review the nodes, only the first item in the array has populated the field collection and no subsequent items have been added. Am I missing something important?

<?php
class IngredientsMigration extends BasicMigration {
  public function __construct($arguments) {
    parent::__construct($arguments);
    $this->description = t('Migrate recipe ingredients from the source database into field collections.');
    $this->dependencies = array('Recipe');

    $query = Database::getConnection('default', 'legacy')
      ->select('recipes', 'r')
      ->fields('r', array('id', 'ingredients'))
        ->condition('r.id', array(2), 'IN');

    $this->source = new MigrateSourceSQL($query);
    $this->destination = new MigrateDestinationFieldCollection(
      'field_collection_ingredients',
      array('host_entity_type' => 'node')
    );

    $this->map = new MigrateSQLMap($this->machineName,
      array(
        'id' => array('type' => 'int',
          'length' => 11,
          'not null' => TRUE,
          'description' => 'Recipe ID',
          'alias' => 'r',
          ),
      ),
      MigrateDestinationFieldCollection::getKeySchema()
    );

    $this->addFieldMapping('host_entity_id', 'id')
      ->sourceMigration('Recipe')
      ->issueNumber(16);
    $this->addFieldMapping('field_ingredient_text', 'ingredients')
      ->description(t('See prepareRow method'))
      ->issueNumber(16);

    $this->addUnmigratedDestinations(array(
      'path',
      )
    );
  }

  public function prepareRow($row) {
    // Always include this fragment at the beginning of every prepareRow()
    // implementation, so parent classes can ignore rows.
    if (parent::prepareRow($row) === FALSE) {
      return FALSE;
    }

    $ingredients_array = preg_split('/$\R?^/m', $row->ingredients);
    $row->ingredients = array();
    foreach ($ingredients_array as $ingredient) {
      $row->ingredients[] = $ingredient;
    }
    return TRUE;
  }
}

Answer 1

I ended up writing a drush command to run before the migration that would take the 'ingredients' field from the source db and create a new table with the ingredients each parsed into their own row and a delta column to keep them in order. I then configured the ingredients migration to point to this table instead of the recipe table.

My DB connection for this migration ended up looking like the following:

$query = Database::getConnection('default', 'legacy')
  ->select('_recipe_ingredients', 'i')
    ->fields('i', array('id', 'recipe_id', 'ingredient'))
    ->orderBy('i.recipe_id')
    ->orderBy('i.delta');

Answer 2

You can also try this (also answered on this question: Migrating to a Field Collection):

Another option is the implement the complete method of the Migration class and populate the field collection programmatically there.

The following code will save a single field collection item to a node.

public function complete($entity, $row) {

  // load the newly created node (just in case entity isn't fully populated).
  $node = node_load($entity->nid);

  // set the values of all field collection fields
  $values = array(
    'field_name' => 'FIELD_COLLECTION_ITEM_FIELD_NAME',
    'field1'     => array(LANGUAGE_NONE => array(array('value' => 'VALUE'))),
    'field3'     => array(LANGUAGE_NONE => array(array('value' => 'VALUE'))),
  );

  // create the field collection item entity
  $item = entity_create('field_collection_item', $values);

  // attach it to the node loaded above
  $item->setHostEntity('node', $node);

  // save the entity
  $item->save();
}

You can modify it to save multiple field collection items fairly easily.

public function complete($entity, $row) {

  // load the newly created node (just in case entity isn't fully populated).
  $node = node_load($entity->nid);

  // loop values to add as field collection items (assumes you have them in a $values array).
  foreach ($values as $key => $value) {

    // set the values of all field collection fields
    $values = array(
      'field_name' => 'FIELD_COLLECTION_ITEM_FIELD_NAME',
      'field1'     => array(LANGUAGE_NONE => array(array('value' => 'VALUE'))),
      'field3'     => array(LANGUAGE_NONE => array(array('value' => 'VALUE'))),
    );

    // create the field collection item entity
    $item = entity_create('field_collection_item', $values);

    // attach it to the node loaded above
    $item->setHostEntity('node', $node);

    // save the entity
    $item->save();
  }
}

NOTE: If you are adding files to the field collection item, they will not be removed on a rollback unless you explicitly do that.