Picture migration

A special case of file migrations, this is used to migrate user pictures if any. With a Drupal 7 source, user pictures are stored in the file_managed table like other files, but earlier Drupal versions simply stored filespecs in the users table. The user_migration argument should not be used here, because pictures should be migrated before users. To handle the chicken-and-egg problem (users reference the picture file IDs, while the file_managed rows reference the owning users), we migrate the pictures first with a default UID, then when we migrate the users we update the picture data with the uid of the newly-created user account.

$picture_arguments = $common_arguments + array(
  'machine_name' => 'ExamplePicture',
  'description' => t('Import Drupal 6 picture files'),
  'default_uid' => 1,
  'source_dir' => '/path/to/files',
  'destination_dir' => 'public://pictures',
);
Migration::registerMigration('DrupalPicture6Migration', 
  $picture_arguments['machine_name'], $picture_arguments);