Exercise.php

<?php
/*
 * Exercise.php - base class for all exercise types
 * Copyright (c) 2003-2005  Erik Schmitt, Philipp Hügelmeyer
 * Copyright (c) 2005-2006  Christa Deiwiks
 * Copyright (c) 2006-2009  Elmar Ludwig, Martin Schröder
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License as
 * published by the Free Software Foundation; either version 2 of
 * the License, or (at your option) any later version.
 */

abstract class Exercise extends SimpleORMap
{
    public $task = [];

    private static $exercise_types = [];

    /**
     * Configure the database mapping.
     */
    protected static function configure($config = [])
    {
        $config['db_table'] = 'vips_exercise';

        $config['serialized_fields']['options'] = 'JSONArrayObject';

        $config['has_and_belongs_to_many']['tests'] = [
            'class_name'        => 'VipsTest',
            'thru_table'        => 'vips_exercise_ref',
            'thru_key'          => 'exercise_id',
            'thru_assoc_key'    => 'test_id'
        ];
        $config['has_and_belongs_to_many']['files'] = [
            'class_name'        => 'VipsFile',
            'thru_table'        => 'vips_file_ref',
            'thru_key'          => 'object_id',
            'thru_assoc_key'    => 'file_id',
            'order_by'          => "AND type = 'exercise' ORDER BY name"
        ];

        $config['has_many']['exercise_refs'] = [
            'class_name'        => 'VipsExerciseRef',
            'assoc_foreign_key' => 'exercise_id',
            'on_delete'         => 'delete'
        ];
        $config['has_many']['file_refs'] = [
            'class_name'        => 'VipsFileRef',
            'assoc_foreign_key' => 'object_id',
            'on_delete'         => 'delete',
            'order_by'          => "AND type = 'exercise'"
        ];
        $config['has_many']['solutions'] = [
            'class_name'        => 'VipsSolution',
            'assoc_foreign_key' => 'exercise_id',
            'on_delete'         => 'delete'
        ];
        $config['has_many']['old_solutions'] = [
            'class_name'        => 'VipsSolutionArchive',
            'assoc_foreign_key' => 'exercise_id',
            'on_delete'         => 'delete'
        ];

        $config['belongs_to']['user'] = [
            'class_name'  => 'User',
            'foreign_key' => 'user_id'
        ];

        parent::configure($config);