FolderDropdownField.php

<?php

/**
 * Represents a TreeDropdownField for folders which remembers the last folder selected
 */
class FolderDropdownField extends TreeDropdownField {

	public function __construct($name, $title = null, $sourceObject = 'Folder', $keyField = 'ID', $labelField = 'TreeTitle', $showSearch = true) {
		parent::__construct($name, $title, $sourceObject, $keyField, $labelField, $showSearch);
		$this->setValue(self::get_last_folder());
	}

	/**
	 * Set the last folder selected
	 *
	 * @param int|Folder $folder Folder instance or ID
	 */
	public static function set_last_folder($folder) {
		if($folder instanceof Folder) {
			$folder = $folder->ID;
		}
		Session::set(get_class().'.FolderID', $folder);
	}

	/**
	 * Get the last folder selected
	 *
	 * @return int
	 */
	public static function get_last_folder() {
		return Session::get(get_class().'.FolderID');
	}

	public function setValue($value) {
		if($value) self::set_last_folder($value);
		parent::setValue($value);
	}
}