path: root/lib/models/Lvgruppe.php

<?php
/**
 * Lvgruppe.php
 * model class for Lehrveranstaltungsgruppen (table mvv_lvgruppe)
 *
 * 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.
 *
 * @author      Peter Thienel <thienel@data-quest.de>
 * @license     http://www.gnu.org/licenses/gpl-2.0.html GPL version 2
 * @category    Stud.IP
 * @since       3.5
 *
 * @property string $id alias column for lvgruppe_id
 * @property string $lvgruppe_id database column
 * @property string $name database column
 * @property I18NString|null $alttext database column
 * @property string $author_id database column
 * @property string $editor_id database column
 * @property int $mkdate database column
 * @property int $chdate database column
 * @property SimpleORMapCollection|Modulteil[] $modulteile has_and_belongs_to_many Modulteil
 * @property SimpleORMapCollection|Course[] $courses has_and_belongs_to_many Course
 * @property SimpleORMapCollection|ArchivedCourse[] $archived_courses has_and_belongs_to_many ArchivedCourse
 * @property mixed $count_seminare additional field
 * @property mixed $count_archiv additional field
 * @property mixed $count_modulteile additional field
 * @property mixed $count_semester additional field
 */

class Lvgruppe extends ModuleManagementModelTreeItem
{
    protected static function configure($config = [])
    {
        $config['db_table'] = 'mvv_lvgruppe';

        $config['has_and_belongs_to_many']['modulteile'] = [
            'class_name' => Modulteil::class,
            'thru_table' => 'mvv_lvgruppe_modulteil',
            'on_delete' => 'delete',
            'on_store' => 'store'
        ];
        $config['has_and_belongs_to_many']['courses'] = [
            'class_name' => Course::class,
            'thru_table' => 'mvv_lvgruppe_seminar',
            'on_delete' => 'delete',
            'on_store' => 'store'
        ];
        $config['has_and_belongs_to_many']['archived_courses'] = [
            'class_name' => ArchivedCourse::class,
            'thru_table' => 'mvv_lvgruppe_seminar',
            'on_delete' => 'delete',
            'on_store' => 'store'
        ];

        $config['additional_fields']['count_seminare']['get'] =
            function($lvgruppe) { return $lvgruppe->count_seminare; };
        $config['additional_fields']['count_seminare']['set'] = false;
        $config['additional_fields']['count_archiv']['get'] =
            function($lvgruppe) { return $lvgruppe->count_archiv; };
        $config['additional_fields']['count_archiv']['set'] = false;
        $config['additional_fields']['count_modulteile']['get'] =
            function($lvgruppe) { return $lvgruppe->count_modulteile; };
        $config['additional_fields']['count_modulteile']['set'] = false;
        $config['additional_fields']['count_semester']['get'] =
            function($lvgruppe) { return $lvgruppe->count_semester; };
        $config['additional_fields']['count_semester']['set'] = false;

        $config['i18n_fields']['alttext'] = true;

        parent::configure($config);
    }

    private $count_seminare;
    private $count_archiv;
    private $count_modulteile;
    private $count_semester;

    public function __construct($id = null)
    {
        parent::__construct($id);
        $this->object_real_name = _('Lehrveranstaltungsgruppe');
    }

    /**
     * @see ModuleManagementModel::getClassDisplayName
     */
    public static function getClassDisplayName($long = false)
    {
        return _('Lehrveranstaltungsgruppe');
    }

    /**
     * Returns all or a specified (by row count and offset) number of
     * Abschluesse sorted and filtered by given parameters and enriched with
     * some additional fields. This function is mainly used in the list view.
     *
     * @param string $sortby Field name to order by.
     * @param string $order ASC or DESC direction of order.
     * @param array $filter Key-value pairs of filed names and values
     * to filter the result set.
     * @param int $row_count The max number of objects to return.
     * @param int $offset The first object to return in a result set.
     * @param string An id of a semester to restrict the result to groups
     * assigned to courses span the semesters time range.
     * @return object A SimpleORMapCollection of Abschluss objects.
     */
    public static function getAllEnriched($sortby = 'name', $order = 'ASC',
            $filter = null, $row_count = null, $offset = null,
            $semester_id = null)
    {
        $sortby = self::createSortStatement($sortby, $order, 'name',
                ['count_seminare', 'count_modulteile', 'count_archiv']);
        $params = [];
        if (!is_null($filter)) {
            $filter_sql = is_array($filter)
                    ? self::getFilterSql($filter, true) : $filter;
        } else {
            $filter_sql = '';
        }
        // get result filtered by a given semester
        $semester_join = '';
        if ($semester_id) {
            $semester = Semester::find($semester_id);
            if ($semester) {
                $filter_sql = trim($filter_sql) ? $filter_sql . ' AND' : $filter_sql . ' WHERE';
                $filter_sql .= ' seminare.start_time <= :beginn '
                        . 'AND (semester_courses.semester_id IS NULL OR semester_courses.semester_id = :semester_id) '
                        . 'AND (start_sem.beginn <= :ende AND '
                        . 'IF(ISNULL(end_sem.ende), 1, end_sem.ende >= :beginn)) ';
                $params = [
                    ':semester_id' => $semester->semester_id,
                    ':beginn' => $semester->beginn,
                    ':ende' => $semester->ende
                ];
                $semester_join = 'LEFT JOIN mvv_modul ON mvv_modul.modul_id = mvv_modulteil.modul_id '
                . 'LEFT JOIN semester_data as start_sem ON start_sem.semester_id = mvv_modul.start '
                . 'LEFT JOIN semester_data as end_sem ON end_sem.semester_id = mvv_modul.end '
                . 'LEFT JOIN semester_courses ON (semester_courses.course_id = seminare.Seminar_id) ';
            }
        }
        $query = 'SELECT mvv_lvgruppe.*, mvv_lvgruppe.lvgruppe_id AS lvg_id, '
                . 'COUNT(DISTINCT seminare.seminar_id) AS `count_seminare`, '
                . 'COUNT(DISTINCT archiv.seminar_id) AS `count_archiv`, '
                // get ALL assigned modulteile, not only the modulteile from modules
                // where the responsible institute is set by the filter
                // (maybe the filter is set to the institutes where the user has a mvv role)
                . 'COALESCE((SELECT COUNT(DISTINCT modulteil_id) FROM mvv_lvgruppe_modulteil '
                    . 'WHERE mvv_lvgruppe_modulteil.lvgruppe_id = lvg_id '
                    . 'GROUP BY lvgruppe_id), 0) AS `count_modulteile` '
                . 'FROM mvv_lvgruppe '
                . 'LEFT JOIN mvv_lvgruppe_seminar USING(lvgruppe_id) '
                . 'LEFT JOIN archiv ON mvv_lvgruppe_seminar.seminar_id = archiv.seminar_id '
                . 'LEFT JOIN seminare ON mvv_lvgruppe_seminar.seminar_id = seminare.seminar_id '
                . 'LEFT JOIN mvv_lvgruppe_modulteil USING(lvgruppe_id) '
                . 'LEFT JOIN mvv_modulteil USING(modulteil_id) '
                . 'LEFT JOIN mvv_modul_inst USING(modul_id) '
                . $semester_join
                . $filter_sql
                . 'GROUP BY lvgruppe_id '
                . 'ORDER BY ' . $sortby;
        return parent::getEnrichedByQuery($query, $params, $row_count, $offset);
    }

    /**
     * Returns the number of LV-Gruppen optionally reduced by
     * filter criteria.
     *
     * @param array $filter Key-value pairs of filed names and values
     * to filter the result.
     * @param string An id of a semester to restrict the result to groups
     * assigned to courses span the semesters time range.
     * @return type
     */
    public static function getCount($filter = null /*, $semester_id = null*/)
    {
        if (!is_null($filter)) {
            $filter_sql = is_array($filter)
                    ? self::getFilterSql($filter, true) : $filter;
        } else {
            $filter_sql = '';
        }
        $num_args = func_num_args();
        $semester_join = '';
        $params = [];
        // get result filtered by a given semester
        if ($num_args == 2) {
            $semester_id = func_get_arg(1);
            $semester = Semester::find($semester_id);
            if ($semester) {
                if (trim($filter_sql)) {
                    $filter_sql .= ' AND';
                } else {
                    $filter_sql .= ' WHERE';
                }

                $filter_sql = trim($filter_sql) ? $filter_sql  : ' AND';
                $filter_sql .= ' seminare.start_time <= :beginn '
                        . 'AND (semester_courses.semester_id IS NULL OR semester_courses.semester_id = :semester_id) '
                        . 'AND (start_sem.beginn <= :ende AND '
                        . 'IF(ISNULL(end_sem.ende), 1, end_sem.ende >= :beginn)) ';
                $params = [
                    ':semester_id' => $semester->semester_id,
                    ':beginn' => $semester->beginn,
                    ':ende' => $semester->ende
                ];
                $semester_join = 'LEFT JOIN mvv_modul ON mvv_modul.modul_id = mvv_modulteil.modul_id '
                . 'LEFT JOIN semester_data as start_sem ON start_sem.semester_id = mvv_modul.start '
                . 'LEFT JOIN semester_data as end_sem ON end_sem.semester_id = mvv_modul.end '
                . 'LEFT JOIN semester_courses ON (semester_courses.course_id = seminare.Seminar_id) ';
            }
        }
        $query = 'SELECT COUNT(DISTINCT(mvv_lvgruppe.lvgruppe_id)) '
                . 'FROM mvv_lvgruppe '
                . 'LEFT JOIN mvv_lvgruppe_seminar USING(lvgruppe_id) '
                . 'LEFT JOIN seminare ON mvv_lvgruppe_seminar.seminar_id = seminare.seminar_id '
                . 'LEFT JOIN mvv_lvgruppe_modulteil USING(lvgruppe_id) '
                . 'LEFT JOIN mvv_modulteil USING(modulteil_id) '
                . 'LEFT JOIN mvv_modul_inst USING(modul_id) '
                . $semester_join
                . $filter_sql;
        $db = DBManager::get()->prepare($query);
        $db->execute($params);
        return $db->fetchColumn(0);
    }

    /**
     * Retrieves all LV-Gruppen by given search term. The term is compared with
     * the name of the LV-Gruppe, the code and the name of related modules
     *
     * @param string $term The search term.
     * @param array|string $filter An array with filter options or a where part.
     * @return object A SimpleORMapCollection of LV-Gruppen.
     */
    public static function findBySearchTerm($term, $filter = null)
    {
        if (!is_null($filter)) {
            $filter_sql = is_array($filter)
                    ? self::getFilterSql($filter) : $filter;
        } else {
            $filter_sql = '';
        }

        $term = '%' . $term . '%';
        return parent::getEnrichedByQuery(
                "SELECT mvv_lvgruppe.*, GROUP_CONCAT(DISTINCT mvv_modul.modul_id SEPARATOR ',') "
                . 'AS `assigned_modul_ids` '
                . 'FROM mvv_lvgruppe '
                . 'INNER JOIN mvv_lvgruppe_modulteil USING(lvgruppe_id) '
                . 'INNER JOIN mvv_modulteil USING(modulteil_id) '
                . 'INNER JOIN mvv_modul USING(modul_id) '
                . 'INNER JOIN mvv_modul_deskriptor USING(modul_id) '
                . 'INNER JOIN mvv_modul_inst USING(modul_id) '
                . 'INNER JOIN mvv_stgteilabschnitt_modul USING(modul_id) '
                . 'INNER JOIN mvv_stgteilabschnitt USING(abschnitt_id) '
                . 'INNER JOIN mvv_stgteilversion USING(version_id) '
                . 'LEFT JOIN semester_data start_sem '
                . 'ON (mvv_modul.start = start_sem.semester_id) '
                . 'LEFT JOIN semester_data end_sem '
                . 'ON (mvv_modul.end = end_sem.semester_id) '
                . 'WHERE (mvv_lvgruppe.name LIKE :search_term OR mvv_modul.code LIKE :search_term '
                . 'OR mvv_modul_deskriptor.bezeichnung LIKE :search_term) '
                . $filter_sql
                . 'GROUP BY lvgruppe_id '
                . 'ORDER BY `name`', [':search_term' => $term]);
    }

    /**
     * Retrieves all LV-Gruppen related to the Modulteil with given id.
     *
     * @param string $modulteil_id The id of a Modulteil.
     * @return object A SimpleORMapCollection of LV-Gruppen.
     */
    public static function findByModulteil($modulteil_id)
    {
        return parent::getEnrichedByQuery('SELECT mlg.* '
                . 'FROM mvv_lvgruppe mlg '
                . 'INNER JOIN mvv_lvgruppe_modulteil mlm USING(lvgruppe_id) '
                . 'WHERE mlm.modulteil_id = ? '
                . 'ORDER BY `position`,`mkdate`', [$modulteil_id]);
    }

    /**
     * Retrieves all LV-Gruppen related to the course with given id.
     *
     * @param string $seminar_id The id of a course.
     * @return object A SimpleORMapCollection of LV-Gruppen.
     */
    public static function findBySeminar($seminar_id)
    {
        return parent::getEnrichedByQuery('SELECT mlg.* '
                . 'FROM mvv_lvgruppe mlg '
                . 'INNER JOIN mvv_lvgruppe_seminar mls USING(lvgruppe_id) '
                . 'WHERE mls.seminar_id = ? '
                . 'ORDER BY `name`', [$seminar_id]);
    }

    /**
     * Returns all institutes assigned to Module.
     *
     * @param string $sortby DB field to sort by.
     * @param string $order ASC or DESC
     * @param array $filter Array of filter.
     * @return array Array of found Fachbereiche.
     */
    public static function getAllAssignedInstitutes($sortby = 'name',
            $order = 'ASC', $filter = null, $row_count = null, $offset = null)
    {
        $sortby = Fachbereich::createSortStatement($sortby, $order, 'name',
                ['count_module']);
        return Fachbereich::getEnrichedByQuery('SELECT Institute.*, '
                . 'Institute.Name as `name`, '
                . 'Institute.Institut_id AS institut_id, '
                . 'COUNT(DISTINCT(lvgruppe_id)) as count_objects '
                . 'FROM mvv_lvgruppe_modulteil '
                . 'INNER JOIN mvv_modulteil USING(modulteil_id) '
                . 'INNER JOIN mvv_modul_inst USING(modul_id) '
                . 'INNER JOIN Institute '
                . 'ON mvv_modul_inst.institut_id = Institute.Institut_id '
                . Fachbereich::getFilterSql($filter, true)
                . 'GROUP BY institut_id ORDER BY ' . $sortby
                , [], $row_count, $offset);
    }

    /**
     * Assigns the given seminar to this lvgruppe.
     *
     * @param string $seminar_id
     * @return int|boolean
     */
    public function addSeminar($seminar_id)
    {
        return LvgruppeSeminar::get([$this->getId(), $seminar_id])
                ->store();
    }

    /**
     * Assigns the given course to the given LvGruppen.
     *
     * @param array Array of ids
     * @return int The number of assigned LvGruppen.
     */
    public static function setLvgruppen($seminar_id, $lvgruppen_ids)
    {
        $old = Lvgruppe::findBySeminar($seminar_id);
        $removed = array_diff($old->pluck('id'), $lvgruppen_ids);
        $added = array_diff($lvgruppen_ids, $old->pluck('id'));
        foreach ($removed as $one) {
            $count_removed += $old->findOneBy('id', $one)->removeSeminar($seminar_id);
        }
        foreach ($added as $one) {
            $count_added += Lvgruppe::get($one)->addSeminar($seminar_id);
        }
        return count($old) + $count_added - $count_removed;
    }

    /**
     * Removes the seminar from this Lvgruppe.
     *
     * @param type $seminar_id
     * @return boolean Always true...
     */
    public function removeSeminar($seminar_id)
    {
        return LvgruppeSeminar::get([$this->getId(), $seminar_id])
                ->delete();
    }

    /**
     * @see MvvTreeItem::getTrailParentId()
     */
    public function getTrailParentId()
    {
        return ($_SESSION['MVV/Lvgruppe/trail_parent_id']);
    }

    /**
     * @see MvvTreeItem::getTrailParent()
     */
    public function getTrailParent()
    {
        return Modul::findCached($this->getTrailParentId());
    }

    /**
     * @see MvvTreeItem::getChildren()
     */
    public function getChildren()
    {
        return [];
    }

    /**
     * @see MvvTreeItem::hasChildren()
     */
    public function hasChildren()
    {
        return false;
    }

    /**
     * @see MvvTreeItem::isAssignable()
     */
    public function isAssignable()
    {
        return true;
    }

    /**
     * @see MvvTreeItem::getParents()
     */
    public function getParents($mode = null)
    {
         return Modulteil::findByLvgruppe($this->getId());
    }

    /**
     * Retrieves courses this LV-Gruppe is assigned to. Filtered by a given
     * semester considering the global visibility or the the visibility
     * for a given user.
     *
     * @param string $semester_id The id of a semester.
     * @param mixed $only_visible Boolean true retrieves only visible courses, false
     * retrieves all courses. If $only_visible is an user id it depends on the users
     * status which courses will be retrieved.
     * @return array An array of course data.
     */
    public function getAssignedCoursesBySemester($semester_id, $only_visible = true)
    {
        $semester = Semester::find($semester_id);
        if ($semester) {
            $sql = 'SELECT seminar_id, Name, VeranstaltungsNummer, sem.visible '
                . 'FROM seminare sem '
                . 'LEFT JOIN mvv_lvgruppe_seminar mls USING(seminar_id) '
                . 'LEFT JOIN semester_courses ON (semester_courses.course_id = sem.Seminar_id) '
                . 'WHERE mls.lvgruppe_id = :id '
                . 'AND ((sem.start_time <= :semester_beginn '
                . 'AND semester_courses.semester_id = :semester_id) '
                . 'OR (sem.start_time BETWEEN :semester_beginn AND :semester_ende) '
                . 'OR (sem.start_time <= :semester_beginn AND semester_courses.semester_id IS NULL)) ';
            if ($only_visible === false) {
                $stmt = DBManager::get()->prepare($sql);
                $stmt->execute([
                    ':id' => $this->getId(),
                    ':semester_id' => $semester->semester_id,
                    ':semester_beginn' => $semester->beginn,
                    ':semester_ende' => $semester->ende
                ]);
            } else if ($only_visible === true) {
                $stmt = DBManager::get()->prepare($sql . ' AND sem.visible = 1 ');
                $stmt->execute([
                    ':id' => $this->getId(),
                    ':semester_id' => $semester->semester_id,
                    ':semester_beginn' => $semester->beginn,
                    ':semester_ende' => $semester->ende
                ]);
            } else {
                $user_perm = $GLOBALS['perm']->get_perm($only_visible);
                if ($user_perm == 'root') {
                    $stmt = DBManager::get()->prepare($sql);
                    $stmt->execute([
                        ':id' => $this->getId(),
                        ':semester_id' => $semester->semester_id,
                        ':semester_beginn' => $semester->beginn,
                        ':semester_ende' => $semester->ende
                    ]);
                } else if ($user_perm == 'admin') {
                    $perm_institute_ids = [];
                    foreach (Institute::getMyInstitutes($only_visible) as $perm_institute) {
                        $perm_institute_ids[] = $perm_institute['Institut_id'];
                    }
                    $stmt = DBManager::get()->prepare($sql
                        . 'AND (sem.visible = 1 OR (sem.visible = 0 '
                        . 'AND sem.institut_id IN (:perm_institutes))) ');
                    $stmt->execute([
                        ':id' => $this->getId(),
                        ':semester_id' => $semester->semester_id,
                        ':semester_beginn' => $semester->beginn,
                        ':semester_ende' => $semester->ende,
                        ':perm_institutes' => $perm_institute_ids
                    ]);
                } else {
                    $stmt = DBManager::get()->prepare('SELECT seminar_id, Name, '
                        . 'VeranstaltungsNummer, sem.visible '
                        . 'FROM seminare sem '
                        . 'LEFT JOIN mvv_lvgruppe_seminar mls USING(seminar_id) '
                        . 'LEFT JOIN semester_courses ON (semester_courses.course_id = sem.Seminar_id) '
                        . 'INNER JOIN seminar_user USING(seminar_id) '
                        . 'WHERE mls.lvgruppe_id = :id '
                        . 'AND ((sem.start_time <= :semester_beginn '
                        . 'AND semester_courses.semester_id = :semester_id) '
                        . 'OR (sem.start_time BETWEEN :semester_beginn AND :semester_ende) '
                        . 'OR (sem.start_time <= :semester_beginn AND semester_courses.semester_id IS NULL)) '
                        . 'AND (sem.visible = 1 OR (sem.visible = 0 AND seminar_user.user_id = :user_id))');
                    $stmt->execute([
                        ':id' => $this->getId(),
                        ':semester_id' => $semester->semester_id,
                        ':semester_beginn' => $semester->beginn,
                        ':semester_ende' => $semester->ende,
                        ':user_id' => $only_visible
                    ]);
                }
            }
            return $stmt->fetchAll(PDO::FETCH_ASSOC);
        }
        return [];
    }

    /**
     * Returns all courses assigned to this LV-Gruppe grouped by semesters.
     *
     * @param bool $only_visible Return only visible courses.
     * @param string $semester_id Return only this semester.
     * @return array All assigned courses grouped by semesters.
     */
    public function getAllAssignedCourses($only_visible = false, $semester_id = null)
    {
        $sem_start_times = [];

        if ($semester_id) {
            $semester = Semester::find($semester_id);
            if (!$semester) {
                return [];
            }
            $sem_start_times[$semester->id] = $semester->beginn;
        } else {
            $sem_start_times = SimpleORMapCollection::createFromArray(
                    Semester::getAll())->toGroupedArray('id', 'beginn');
            $sem_start_times = array_map(
                    function ($sem) { return $sem['beginn']; }
                    , $sem_start_times);
        }
        $visible_sql = $only_visible ? ' AND visible = 1' : '';
        $courses = [];
        $stmt = DBManager::get()->prepare('SELECT seminar_id, Name, '
                . 'VeranstaltungsNummer, visible, INTERVAL(start_time,'
                . join(',', $sem_start_times)
                . ') AS sem_number, '
                . 'IF(duration_time=-1,' . count($sem_start_times)
                . ',INTERVAL(start_time+duration_time,'
                . join(',', $sem_start_times)
                . ')) AS sem_number_end FROM seminare '
                . 'INNER JOIN mvv_lvgruppe_seminar USING(seminar_id) '
                . 'WHERE lvgruppe_id = ? ' . $visible_sql
                . ' AND start_time <= ' . end($sem_start_times)
                . ' ORDER BY sem_number DESC, Name');
        $stmt->execute([$this->getId()]);
        $sem_ids = array_keys($sem_start_times);
        foreach ($stmt->fetchAll(PDO::FETCH_ASSOC) as $course) {
            if ($course['sem_number'] == 0) $course['sem_number'] = 1;
            for ($i = $course['sem_number']; $i <= $course['sem_number_end']; $i++) {
                $courses[$sem_ids[$i-1]][] = $course;
            }
        }
        return $courses;
    }

    /**
     * Returns all archived courses previously assigned to this LV-Gruppe.
     *
     * @return array All archived courses.
     */
    public function getArchivedCourses()
    {
        $stmt = DBManager::get()->prepare('SELECT seminar_id, name, semester '
                . 'FROM mvv_lvgruppe_seminar '
                . 'INNER JOIN archiv USING(seminar_id) '
                . 'WHERE lvgruppe_id = ? '
                . 'ORDER BY start_time ASC');
        $stmt->execute([$this->getId()]);
        return $stmt->fetchAll(PDO::FETCH_ASSOC);
    }

    /**
     * Returns a default name for a new LV-Gruppe derived from a given
     * modulteil.
     *
     * @param string $modulteil_id The id of a Modulteil.
     * @return string The default name.
     */
    public static function getDefaultName($modulteil_id)
    {
        $name = '';
        /*
         * Gießen
        $modul = Modul::find($modul_id);
        if ($modul) {
            $name = $modul->responsible_institute->institute->getShortName();
            $short_name_modul = $modul->getDeskriptor(
                    $GLOBALS['MVV_MODUL_DESKRIPTOR']['SPRACHE']['default'])
                    ->bezeichnung_kurz;
            $name .= $short_name_modul ? ' ' . $short_name_modul : '';
        }
         *
         */
        // Augsburg
        $modulteil = Modulteil::findCached($modulteil_id);
        if ($modulteil) {
            $name = $modulteil->getDeskriptor()->bezeichnung;
            //$name = $name_modulteil ? ' ' . $name_modulteil : '';
        }
        return $name;
    }

    public function validate()
    {
        $ret = parent::validate();
        if ($this->isDirty()) {
            $messages = [];
            $rejected = false;

            // The name of the Fach must be longer than 4 characters
            if (mb_strlen($this->name) < 4) {
                $ret['name'] = true;
                $messages[] = _('Der Name der Lehrveranstaltungsgruppe ist zu kurz (mindestens 4 Zeichen).');
                $rejected = true;
            } else {
                if ($this->isNew()) {
                    // The name of the Lehrveranstaltungsgruppe has to be unique
                    $existing = $this->findBySql('name = ' . DBManager::get()->quote($this->name));
                    if (sizeof($existing)) {
                        $ret['name'] = true;
                        $messages[] = sprintf(_('Es existiert bereits eine Lehrveranstaltungsgruppe mit dem Namen "%s"!'),
                                $this->name);
                        $rejected = true;
                    }
                }
            }
            if ($rejected) {
                throw new InvalidValuesException(join("\n", $messages), $ret);
            }
        }
        return $ret;
    }

}