silverstripe-userforms/code/tasks/UserFormsColumnCleanTask.php

<?php

/**
 * UserForms Column Clean Task
 *
 * Column clean up tasks for Userforms
 *
 * @package userforms
 */

class UserFormsColumnCleanTask extends MigrationTask {

	protected $title = "UserForms EditableFormField Column Clean task";

	protected $description = "Removes unused columns from EditableFormField for MySQL databases;";

	protected $tables = array('EditableFormField');

	protected $keepColumns = array('ID');

	/**
	 * Publish the existing forms.
	 *
	 */
	public function run($request) {
		foreach ($this->tables as $db) {
			$obj = new $db();
			$columns = $obj->database_fields($db);
			$query = "SHOW COLUMNS FROM $db";
			$liveColumns = DB::query($query)->column();
			$backedUp = 0;
			$query = "SHOW TABLES LIKE 'Backup_$db'";
			$tableExists = DB::query($query)->value();
			if ($tableExists != null) {
				echo "Tasks run already on $db exiting";
				return;
			}
			$backedUp = 0;
			foreach ($liveColumns as $index => $column) {
				if ($backedUp == 0) {
					echo "Backing up $db <br />";
					echo "Creating Backup_$db <br />";
					// backup table
					$query = "CREATE TABLE Backup_$db LIKE $db";
					DB::query($query);
					echo "Populating Backup_$db <br />";
					$query = "INSERT Backup_$db SELECT * FROM $db";
					DB::query($query);
					$backedUp = 1;
				}
				if (!isset($columns[$column]) && !in_array($column, $this->keepColumns)) {
					echo "Dropping $column from $db <br />";
					$query = "ALTER TABLE $db DROP COLUMN $column";
					DB::query($query);
				}
			}
		}
	}
}