/**
  * @param string $name
  * @param string $title
  * @param DataObjectInterface $object
  * @param string $sort
  * @param SS_List $source
  * @param string $titleField
  */
 public function __construct($name, $title, DataObjectInterface $object, $sort = false, SS_List $source = null, $titleField = 'Title')
 {
     $this->setSort($sort);
     if ($object->many_many($name)) {
         $dataSource = $object->{$name}();
         // Check if we're dealing with an UnsavedRelationList
         $unsaved = $dataSource instanceof UnsavedRelationList;
         // Store the relation's class name
         $class = $dataSource->dataClass();
         $this->dataClass = $class;
         // Sort the items
         if ($this->getSort()) {
             $dataSource = $dataSource->sort($this->getSort());
         }
         // If we're dealing with an UnsavedRelationList, it'll be empty, so we
         // can skip this and just use an array of all available items
         if ($unsaved) {
             $dataSource = $class::get()->map()->toArray();
         } else {
             // If we've been given a list source, filter on those IDs only.
             if ($source) {
                 $dataSource = $dataSource->filter('ID', $source->column('ID'));
             }
             // Start building the data source from scratch. Currently selected items first,
             // in the correct sort order
             $dataSource = $dataSource->map('ID', $titleField)->toArray();
             // Get the other items
             $theRest = $class::get();
             // Exclude items that we've already found
             if (!empty($dataSource)) {
                 $theRest = $theRest->exclude('ID', array_keys($dataSource));
             }
             // If we've been given a list source, filter on those IDs only
             if ($source) {
                 $theRest = $theRest->filter('ID', $source->column('ID'));
             }
             $theRest = $theRest->map('ID', $titleField)->toArray();
             // ... we then add the remaining items in whatever order they come
             $dataSource = $dataSource + $theRest;
         }
     } elseif ($source instanceof SS_List) {
         $dataSource = $source->map('ID', $titleField)->toArray();
     } elseif (is_array($source) && ArrayLib::is_associative($source)) {
         $dataSource = $source;
     } else {
         user_error('MultiSelectField::__construct(): MultiSelectField only supports many-to-many relations');
     }
     parent::__construct($name, $title, $dataSource, '', null, true);
 }
 public function column($value = 'ID')
 {
     return $this->list->column($value);
 }