moodle/lib/db/upgradelib.php

<?php
// This file is part of Moodle - http://moodle.org/
//
// Moodle 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 3 of the License, or
// (at your option) any later version.
//
// Moodle is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU General Public License for more details.
//
// You should have received a copy of the GNU General Public License
// along with Moodle.  If not, see <http://www.gnu.org/licenses/>.

/**
 * Upgrade helper functions
 *
 * This file is used for special upgrade functions - for example groups and gradebook.
 * These functions must use SQL and database related functions only- no other Moodle API,
 * because it might depend on db structures that are not yet present during upgrade.
 * (Do not use functions from accesslib.php, grades classes or group functions at all!)
 *
 * @package   core_install
 * @category  upgrade
 * @copyright 2007 Petr Skoda (http://skodak.org)
 * @license   http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
 */

defined('MOODLE_INTERNAL') || die();

/**
 * Returns all non-view and non-temp tables with sane names.
 * Prints list of non-supported tables using $OUTPUT->notification()
 *
 * @return array
 */
function upgrade_mysql_get_supported_tables() {
    global $OUTPUT, $DB;

    $tables = array();
    $patprefix = str_replace('_', '\\_', $DB->get_prefix());
    $pregprefix = preg_quote($DB->get_prefix(), '/');

    $sql = "SHOW FULL TABLES LIKE '$patprefix%'";
    $rs = $DB->get_recordset_sql($sql);
    foreach ($rs as $record) {
        $record = array_change_key_case((array)$record, CASE_LOWER);
        $type = $record['table_type'];
        unset($record['table_type']);
        $fullname = array_shift($record);

        if ($pregprefix === '') {
            $name = $fullname;
        } else {
            $count = null;
            $name = preg_replace("/^$pregprefix/", '', $fullname, -1, $count);
            if ($count !== 1) {
                continue;
            }
        }

        if (!preg_match("/^[a-z][a-z0-9_]*$/", $name)) {
            echo $OUTPUT->notification("Database table with invalid name '$fullname' detected, skipping.", 'notifyproblem');
            continue;
        }
        if ($type === 'VIEW') {
            echo $OUTPUT->notification("Unsupported database table view '$fullname' detected, skipping.", 'notifyproblem');
            continue;
        }
        $tables[$name] = $name;
    }
    $rs->close();

    return $tables;
}

/**
 * Remove all signed numbers from current database and change
 * text fields to long texts - mysql only.
 */
function upgrade_mysql_fix_unsigned_and_lob_columns() {
    // We are not using standard API for changes of column
    // because everything 'signed'-related will be removed soon.

    // If anybody already has numbers higher than signed limit the execution stops
    // and tables must be fixed manually before continuing upgrade.

    global $DB;

    if ($DB->get_dbfamily() !== 'mysql') {
        return;
    }

    $pbar = new progress_bar('mysqlconvertunsignedlobs', 500, true);

    $prefix = $DB->get_prefix();
    $tables = upgrade_mysql_get_supported_tables();

    $tablecount = count($tables);
    $i = 0;
    foreach ($tables as $table) {
        $i++;

        $changes = array();

        $sql = "SHOW COLUMNS FROM `{{$table}}`";
        $rs = $DB->get_recordset_sql($sql);
        foreach ($rs as $column) {
            $column = (object)array_change_key_case((array)$column, CASE_LOWER);
            if (stripos($column->type, 'unsigned') !== false) {
                $maxvalue = 0;
                if (preg_match('/^int/i', $column->type)) {
                    $maxvalue = 2147483647;
                } else if (preg_match('/^medium/i', $column->type)) {
                    $maxvalue = 8388607;
                } else if (preg_match('/^smallint/i', $column->type)) {
                    $maxvalue = 32767;
                } else if (preg_match('/^tinyint/i', $column->type)) {
                    $maxvalue = 127;
                }
                if ($maxvalue) {
                    // Make sure nobody is abusing our integer ranges - moodle int sizes are in digits, not bytes!!!
                    $invalidcount = $DB->get_field_sql("SELECT COUNT('x') FROM `{{$table}}` WHERE `$column->field` > :maxnumber", array('maxnumber'=>$maxvalue));
                    if ($invalidcount) {
                        throw new moodle_exception('notlocalisederrormessage', 'error', new moodle_url('/admin/'), "Database table '{$table}'' contains unsigned column '{$column->field}' with $invalidcount values that are out of allowed range, upgrade can not continue.");
                    }
                }
                $type = preg_replace('/unsigned/i', 'signed', $column->type);
                $notnull = ($column->null === 'NO') ? 'NOT NULL' : 'NULL';
                $default = (!is_null($column->default) and $column->default !== '') ? "DEFAULT '$column->default'" : '';
                $autoinc = (stripos($column->extra, 'auto_increment') !== false) ? 'AUTO_INCREMENT' : '';
                // Primary and unique not necessary here, change_database_structure does not add prefix.
                $changes[] = "MODIFY COLUMN `$column->field` $type $notnull $default $autoinc";

            } else if ($column->type === 'tinytext' or $column->type === 'mediumtext' or $column->type === 'text') {
                $notnull = ($column->null === 'NO') ? 'NOT NULL' : 'NULL';
                $default = (!is_null($column->default) and $column->default !== '') ? "DEFAULT '$column->default'" : '';
                // Primary, unique and inc are not supported for texts.
                $changes[] = "MODIFY COLUMN `$column->field` LONGTEXT $notnull $default";

            } else if ($column->type === 'tinyblob' or $column->type === 'mediumblob' or $column->type === 'blob') {
                $notnull = ($column->null === 'NO') ? 'NOT NULL' : 'NULL';
                $default = (!is_null($column->default) and $column->default !== '') ? "DEFAULT '$column->default'" : '';
                // Primary, unique and inc are not supported for blobs.
                $changes[] = "MODIFY COLUMN `$column->field` LONGBLOB $notnull $default";
            }

        }
        $rs->close();

        if ($changes) {
            // Set appropriate timeout - 1 minute per thousand of records should be enough, min 60 minutes just in case.
            $count = $DB->count_records($table, array());
            $timeout = ($count/1000)*60;
            $timeout = ($timeout < 60*60) ? 60*60 : (int)$timeout;
            upgrade_set_timeout($timeout);

            $sql = "ALTER TABLE `{$prefix}$table` ".implode(', ', $changes);
            $DB->change_database_structure($sql);
        }

        $pbar->update($i, $tablecount, "Converted unsigned/lob columns in MySQL database - $i/$tablecount.");
    }
}

/**
 * Migrate NTEXT to NVARCHAR(MAX).
 */
function upgrade_mssql_nvarcharmax() {
    global $DB;

    if ($DB->get_dbfamily() !== 'mssql') {
        return;
    }

    $pbar = new progress_bar('mssqlconvertntext', 500, true);

    $prefix = $DB->get_prefix();
    $tables = $DB->get_tables(false);

    $tablecount = count($tables);
    $i = 0;
    foreach ($tables as $table) {
        $i++;

        $columns = array();

        $sql = "SELECT column_name
                  FROM INFORMATION_SCHEMA.COLUMNS
                 WHERE table_name = '{{$table}}' AND UPPER(data_type) = 'NTEXT'";
        $rs = $DB->get_recordset_sql($sql);
        foreach ($rs as $column) {
            $columns[] = $column->column_name;
        }
        $rs->close();

        if ($columns) {
            // Set appropriate timeout - 1 minute per thousand of records should be enough, min 60 minutes just in case.
            $count = $DB->count_records($table, array());
            $timeout = ($count/1000)*60;
            $timeout = ($timeout < 60*60) ? 60*60 : (int)$timeout;
            upgrade_set_timeout($timeout);

            $updates = array();
            foreach ($columns as $column) {
                // Change the definition.
                $sql = "ALTER TABLE {$prefix}$table ALTER COLUMN $column NVARCHAR(MAX)";
                $DB->change_database_structure($sql);
                $updates[] = "$column = $column";
            }

            // Now force the migration of text data to new optimised storage.
            $sql = "UPDATE {{$table}} SET ".implode(', ', $updates);
            $DB->execute($sql);
        }

        $pbar->update($i, $tablecount, "Converted NTEXT to NVARCHAR(MAX) columns in MS SQL Server database - $i/$tablecount.");
    }
}

/**
 * Migrate IMAGE to VARBINARY(MAX).
 */
function upgrade_mssql_varbinarymax() {
    global $DB;

    if ($DB->get_dbfamily() !== 'mssql') {
        return;
    }

    $pbar = new progress_bar('mssqlconvertimage', 500, true);

    $prefix = $DB->get_prefix();
    $tables = $DB->get_tables(false);

    $tablecount = count($tables);
    $i = 0;
    foreach ($tables as $table) {
        $i++;

        $columns = array();

        $sql = "SELECT column_name
                  FROM INFORMATION_SCHEMA.COLUMNS
                 WHERE table_name = '{{$table}}' AND UPPER(data_type) = 'IMAGE'";
        $rs = $DB->get_recordset_sql($sql);
        foreach ($rs as $column) {
            $columns[] = $column->column_name;
        }
        $rs->close();

        if ($columns) {
            // Set appropriate timeout - 1 minute per thousand of records should be enough, min 60 minutes just in case.
            $count = $DB->count_records($table, array());
            $timeout = ($count/1000)*60;
            $timeout = ($timeout < 60*60) ? 60*60 : (int)$timeout;
            upgrade_set_timeout($timeout);

            foreach ($columns as $column) {
                // Change the definition.
                $sql = "ALTER TABLE {$prefix}$table ALTER COLUMN $column VARBINARY(MAX)";
                $DB->change_database_structure($sql);
            }

            // Binary columns should not be used, do not waste time optimising the storage.
        }

        $pbar->update($i, $tablecount, "Converted IMAGE to VARBINARY(MAX) columns in MS SQL Server database - $i/$tablecount.");
    }
}

/**
 * This upgrade script fixes the mismatches between DB fields course_modules.section
 * and course_sections.sequence. It makes sure that each module is included
 * in the sequence of at least one section.
 * Note that this script is different from admin/cli/fix_course_sortorder.php
 * in the following ways:
 * 1. It does not fix the cases when module appears several times in section(s) sequence(s) -
 *    it will be done automatically on the next viewing of the course.
 * 2. It does not remove non-existing modules from section sequences - administrator
 *    has to run the CLI script to do it.
 * 3. When this script finds an orphaned module it adds it to the section but makes hidden
 *    where CLI script does not change the visiblity specified in the course_modules table.
 */
function upgrade_course_modules_sequences() {
    global $DB;

    // Find all modules that point to the section which does not point back to this module.
    $sequenceconcat = $DB->sql_concat("','", "s.sequence", "','");
    $moduleconcat = $DB->sql_concat("'%,'", "m.id", "',%'");
    $sql = "SELECT m.id, m.course, m.section, s.sequence
        FROM {course_modules} m LEFT OUTER JOIN {course_sections} s
        ON m.course = s.course and m.section = s.id
        WHERE s.sequence IS NULL OR ($sequenceconcat NOT LIKE $moduleconcat)
        ORDER BY m.course";
    $rs = $DB->get_recordset_sql($sql);
    $sections = null;
    foreach ($rs as $cm) {
        if (!isset($sections[$cm->course])) {
            // Retrieve all sections for the course (only once for each corrupt course).
            $sections = array($cm->course =>
                    $DB->get_records('course_sections', array('course' => $cm->course),
                            'section', 'id, section, sequence, visible'));
            if (empty($sections[$cm->course])) {
                // Very odd - the course has a module in it but has no sections. Create 0-section.
                $newsection = array('sequence' => '', 'section' => 0, 'visible' => 1);
                $newsection['id'] = $DB->insert_record('course_sections',
                        $newsection + array('course' => $cm->course, 'summary' => '', 'summaryformat' => FORMAT_HTML));
                $sections[$cm->course] = array($newsection['id'] => (object)$newsection);
            }
        }
        // Attempt to find the section that has this module in it's sequence.
        // If there are several of them, pick the last because this is what get_fast_modinfo() does.
        $sectionid = null;
        foreach ($sections[$cm->course] as $section) {
            if (!empty($section->sequence) && in_array($cm->id, preg_split('/,/', $section->sequence))) {
                $sectionid = $section->id;
            }
        }
        if ($sectionid) {
            // Found the section. Update course_module to point to the correct section.
            $params = array('id' => $cm->id, 'section' => $sectionid);
            if (!$sections[$cm->course][$sectionid]->visible) {
                $params['visible'] = 0;
            }
            $DB->update_record('course_modules', $params);
        } else {
            // No section in the course has this module in it's sequence.
            if (isset($sections[$cm->course][$cm->section])) {
                // Try to add module to the section it points to (if it is valid).
                $sectionid = $cm->section;
            } else {
                // Section not found. Just add to the first available section.
                reset($sections[$cm->course]);
                $sectionid = key($sections[$cm->course]);
            }
            $newsequence = ltrim($sections[$cm->course][$sectionid]->sequence . ',' . $cm->id, ',');
            $sections[$cm->course][$sectionid]->sequence = $newsequence;
            $DB->update_record('course_sections', array('id' => $sectionid, 'sequence' => $newsequence));
            // Make module invisible because it was not displayed at all before this upgrade script.
            $DB->update_record('course_modules', array('id' => $cm->id, 'section' => $sectionid, 'visible' => 0, 'visibleold' => 0));
        }
    }
    $rs->close();
    unset($sections);

    // Note that we don't need to reset course cache here because it is reset automatically after upgrade.
}

/**
 * Updates a single item (course module or course section) to transfer the
 * availability settings from the old to the new format.
 *
 * Note: We do not convert groupmembersonly for modules at present. If we did,
 * $groupmembersonly would be set to the groupmembersonly option for the
 * module. Since we don't, it will be set to 0 for modules, and 1 for sections
 * if they have a grouping.
 *
 * @param int $groupmembersonly 1 if activity has groupmembersonly option
 * @param int $groupingid Grouping id (0 = none)
 * @param int $availablefrom Available from time (0 = none)
 * @param int $availableuntil Available until time (0 = none)
 * @param int $showavailability Show availability (1) or hide activity entirely
 * @param array $availrecs Records from course_modules/sections_availability
 * @param array $fieldrecs Records from course_modules/sections_avail_fields
 */
function upgrade_availability_item($groupmembersonly, $groupingid,
        $availablefrom, $availableuntil, $showavailability,
        array $availrecs, array $fieldrecs) {
    global $CFG, $DB;
    $conditions = array();
    $shows = array();

    // Group members only condition (if enabled).
    if ($CFG->enablegroupmembersonly && $groupmembersonly) {
        if ($groupingid) {
            $conditions[] = '{"type":"grouping"' .
                    ($groupingid ? ',"id":' . $groupingid : '') . '}';
        } else {
            // No grouping specified, so allow any group.
            $conditions[] = '{"type":"group"}';
        }
        // Group members only condition was not displayed to students.
        $shows[] = 'false';

        // In the unlikely event that the site had enablegroupmembers only
        // but NOT enableavailability, we need to turn this on now.
        if (!$CFG->enableavailability) {
            set_config('enableavailability', 1);
        }
    }

    // Date conditions.
    if ($availablefrom) {
        $conditions[] = '{"type":"date","d":">=","t":' . $availablefrom . '}';
        $shows[] = $showavailability ? 'true' : 'false';
    }
    if ($availableuntil) {
        $conditions[] = '{"type":"date","d":"<","t":' . $availableuntil . '}';
        // Until dates never showed to students.
        $shows[] = 'false';
    }

    // Conditions from _availability table.
    foreach ($availrecs as $rec) {
        if (!empty($rec->sourcecmid)) {
            // Completion condition.
            $conditions[] = '{"type":"completion","cm":' . $rec->sourcecmid .
                    ',"e":' . $rec->requiredcompletion . '}';
        } else {
            // Grade condition.
            $minmax = '';
            if (!empty($rec->grademin)) {
                $minmax .= ',"min":' . sprintf('%.5f', $rec->grademin);
            }
            if (!empty($rec->grademax)) {
                $minmax .= ',"max":' . sprintf('%.5f', $rec->grademax);
            }
            $conditions[] = '{"type":"grade","id":' . $rec->gradeitemid . $minmax . '}';
        }
        $shows[] = $showavailability ? 'true' : 'false';
    }

    // Conditions from _fields table.
    foreach ($fieldrecs as $rec) {
        if (isset($rec->userfield)) {
            // Standard field.
            $fieldbit = ',"sf":' . json_encode($rec->userfield);
        } else {
            // Custom field.
            $fieldbit = ',"cf":' . json_encode($rec->shortname);
        }
        // Value is not included for certain operators.
        switch($rec->operator) {
            case 'isempty':
            case 'isnotempty':
                $valuebit = '';
                break;

            default:
                $valuebit = ',"v":' . json_encode($rec->value);
                break;
        }
        $conditions[] = '{"type":"profile","op":"' . $rec->operator . '"' .
                $fieldbit . $valuebit . '}';
        $shows[] = $showavailability ? 'true' : 'false';
    }

    // If there are some conditions, set them into database.
    if ($conditions) {
        return '{"op":"&","showc":[' . implode(',', $shows) . '],' .
                '"c":[' . implode(',', $conditions) . ']}';
    } else {
        return null;
    }
}

/**
 * Using data for a single course-module that has groupmembersonly enabled,
 * returns the new availability value that incorporates the correct
 * groupmembersonly option.
 *
 * Included as a function so that it can be shared between upgrade and restore,
 * and unit-tested.
 *
 * @param int $groupingid Grouping id for the course-module (0 if none)
 * @param string $availability Availability JSON data for the module (null if none)
 * @return string New value for availability for the module
 */
function upgrade_group_members_only($groupingid, $availability) {
    // Work out the new JSON object representing this option.
    if ($groupingid) {
        // Require specific grouping.
        $condition = (object)array('type' => 'grouping', 'id' => (int)$groupingid);
    } else {
        // No grouping specified, so require membership of any group.
        $condition = (object)array('type' => 'group');
    }

    if (is_null($availability)) {
        // If there are no conditions using the new API then just set it.
        $tree = (object)array('op' => '&', 'c' => array($condition), 'showc' => array(false));
    } else {
        // There are existing conditions.
        $tree = json_decode($availability);
        switch ($tree->op) {
            case '&' :
                // For & conditions we can just add this one.
                $tree->c[] = $condition;
                $tree->showc[] = false;
                break;
            case '!|' :
                // For 'not or' conditions we can add this one
                // but negated.
                $tree->c[] = (object)array('op' => '!&', 'c' => array($condition));
                $tree->showc[] = false;
                break;
            default:
                // For the other two (OR and NOT AND) we have to add
                // an extra level to the tree.
                $tree = (object)array('op' => '&', 'c' => array($tree, $condition),
                        'showc' => array($tree->show, false));
                // Inner trees do not have a show option, so remove it.
                unset($tree->c[0]->show);
                break;
        }
    }

    return json_encode($tree);
}

/**
 * Updates the mime-types for files that exist in the database, based on their
 * file extension.
 *
 * @param array $filetypes Array with file extension as the key, and mimetype as the value
 */
function upgrade_mimetypes($filetypes) {
    global $DB;
    $select = $DB->sql_like('filename', '?', false);
    foreach ($filetypes as $extension=>$mimetype) {
        $DB->set_field_select(
            'files',
            'mimetype',
            $mimetype,
            $select,
            array($extension)
        );
    }
}

/**
 * Marks all courses with changes in extra credit weight calculation
 *
 * Used during upgrade and in course restore process
 *
 * This upgrade script is needed because we changed the algorithm for calculating the automatic weights of extra
 * credit items and want to prevent changes in the existing student grades.
 *
 * @param int $onlycourseid
 */
function upgrade_extra_credit_weightoverride($onlycourseid = 0) {
    global $DB;

    // Find all courses that have categories in Natural aggregation method where there is at least one extra credit
    // item and at least one item with overridden weight.
    $courses = $DB->get_fieldset_sql(
        "SELECT DISTINCT gc.courseid
          FROM {grade_categories} gc
          INNER JOIN {grade_items} gi ON gc.id = gi.categoryid AND gi.weightoverride = :weightoverriden
          INNER JOIN {grade_items} gie ON gc.id = gie.categoryid AND gie.aggregationcoef = :extracredit
          WHERE gc.aggregation = :naturalaggmethod" . ($onlycourseid ? " AND gc.courseid = :onlycourseid" : ''),
        array('naturalaggmethod' => 13,
            'weightoverriden' => 1,
            'extracredit' => 1,
            'onlycourseid' => $onlycourseid,
        )
    );
    foreach ($courses as $courseid) {
        $gradebookfreeze = get_config('core', 'gradebook_calculations_freeze_' . $courseid);
        if (!$gradebookfreeze) {
            set_config('gradebook_calculations_freeze_' . $courseid, 20150619);
        }
    }
}

/**
 * Marks all courses that require calculated grade items be updated.
 *
 * Used during upgrade and in course restore process.
 *
 * This upgrade script is needed because the calculated grade items were stuck with a maximum of 100 and could be changed.
 * This flags the courses that are affected and the grade book is frozen to retain grade integrity.
 *
 * @param int $courseid Specify a course ID to run this script on just one course.
 */
function upgrade_calculated_grade_items($courseid = null) {
    global $DB, $CFG;

    $affectedcourses = array();
    $possiblecourseids = array();
    $params = array();
    $singlecoursesql = '';
    if (isset($courseid)) {
        $singlecoursesql = "AND ns.id = :courseid";
        $params['courseid'] = $courseid;
    }
    $siteminmaxtouse = $CFG->grade_minmaxtouse;
    $courseidsql = "SELECT ns.id
                      FROM (
                        SELECT c.id, coalesce(" . $DB->sql_compare_text('gs.value') . ", :siteminmax) AS gradevalue
                          FROM {course} c
                          LEFT JOIN {grade_settings} gs
                            ON c.id = gs.courseid
                           AND ((gs.name = 'minmaxtouse' AND " . $DB->sql_compare_text('gs.value') . " = '2'))
                        ) ns
                    WHERE " . $DB->sql_compare_text('ns.gradevalue') . " = '2' $singlecoursesql";
    $params['siteminmax'] = $siteminmaxtouse;
    $courses = $DB->get_records_sql($courseidsql, $params);
    foreach ($courses as $course) {
        $possiblecourseids[$course->id] = $course->id;
    }

    if (!empty($possiblecourseids)) {
        list($sql, $params) = $DB->get_in_or_equal($possiblecourseids);
        // A calculated grade item grade min != 0 and grade max != 100 and the course setting is set to
        // "Initial min and max grades".
        $coursesql = "SELECT DISTINCT courseid
                        FROM {grade_items}
                       WHERE calculation IS NOT NULL
                         AND itemtype = 'manual'
                         AND (grademax <> 100 OR grademin <> 0)
                         AND courseid $sql";
        $affectedcourses = $DB->get_records_sql($coursesql, $params);
    }

    // Check for second type of affected courses.
    // If we already have the courseid parameter set in the affectedcourses then there is no need to run through this section.
    if (!isset($courseid) || !in_array($courseid, $affectedcourses)) {
        $singlecoursesql = '';
        $params = array();
        if (isset($courseid)) {
            $singlecoursesql = "AND courseid = :courseid";
            $params['courseid'] = $courseid;
        }
        $nestedsql = "SELECT id
                        FROM {grade_items}
                       WHERE itemtype = 'category'
                         AND calculation IS NOT NULL $singlecoursesql";
        $calculatedgradecategories = $DB->get_records_sql($nestedsql, $params);
        $categoryids = array();
        foreach ($calculatedgradecategories as $key => $gradecategory) {
            $categoryids[$key] = $gradecategory->id;
        }

        if (!empty($categoryids)) {
            list($sql, $params) = $DB->get_in_or_equal($categoryids);
            // A category with a calculation where the raw grade min and the raw grade max don't match the grade min and grade max
            // for the category.
            $coursesql = "SELECT DISTINCT gi.courseid
                            FROM {grade_grades} gg, {grade_items} gi
                           WHERE gi.id = gg.itemid
                             AND (gg.rawgrademax <> gi.grademax OR gg.rawgrademin <> gi.grademin)
                             AND gi.id $sql";
            $additionalcourses = $DB->get_records_sql($coursesql, $params);
            foreach ($additionalcourses as $key => $additionalcourse) {
                if (!array_key_exists($key, $affectedcourses)) {
                    $affectedcourses[$key] = $additionalcourse;
                }
            }
        }
    }

    foreach ($affectedcourses as $courseid) {
        // Check to see if the gradebook freeze is already in affect.
        $gradebookfreeze = get_config('core', 'gradebook_calculations_freeze_' . $courseid->courseid);
        if (!$gradebookfreeze) {
            set_config('gradebook_calculations_freeze_' . $courseid->courseid, 20150627);
        }
    }
}