Skip to content

Commit

Permalink
MDL-38228 upgrade: Rewrite script that fixes corrupt course modules t…
Browse files Browse the repository at this point in the history 
…o sequence relation
  • Loading branch information
@marinaglancy
marinaglancy committed Nov 5, 2013
1 parent 55e3c2c commit ba5ecbc
Show file tree
Hide file tree
Showing 2 changed files with 164 additions and 0 deletions.
20 changes: 20 additions & 0 deletions lib/db/upgrade.php
View file
Expand Up @@ -1552,6 +1552,8 @@ function xmldb_main_upgrade($oldversion) {
}

if ($oldversion < 2012120301.11) {
// This upgrade step is re-written under MDL-38228 (see below).
/*
// Retrieve the list of course_sections as a recordset to save memory
$coursesections = $DB->get_recordset('course_sections', null, 'course, id', 'id, course, sequence');
foreach ($coursesections as $coursesection) {
Expand Down Expand Up @@ -1595,6 +1597,7 @@ function xmldb_main_upgrade($oldversion) {
}
}
$coursesections->close();
*/

// Main savepoint reached.
upgrade_main_savepoint(true, 2012120301.11);
Expand All @@ -1611,6 +1614,22 @@ function xmldb_main_upgrade($oldversion) {
}

if ($oldversion < 2012120302.01) {
// MDL-38228. Single script to upgrade course_modules instead of 2012120301.11.
// It replaces two scripts (now commented out) introduced in MDL-37939 and MDL-38173.

// 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 only one section and that course_modules.section points back to it.

// This script in included in each major version upgrade process so make sure we don't run it twice.
if (empty($CFG->movingmoduleupgradescriptwasrun)) {
upgrade_course_modules_sequences();

// To skip running the same script on the upgrade to the next major release.
set_config('movingmoduleupgradescriptwasrun', 1);
}

/*
// Retrieve the list of course_sections as a recordset to save memory.
// This is to fix a regression caused by MDL-37939.
// In this case the upgrade step is fixing records where:
Expand Down Expand Up @@ -1667,6 +1686,7 @@ function xmldb_main_upgrade($oldversion) {
}
}
$coursesections->close();
*/

upgrade_main_savepoint(true, 2012120302.01);
}
Expand Down
144 changes: 144 additions & 0 deletions lib/db/upgradelib.php
View file
Expand Up @@ -164,3 +164,147 @@ function upgrade_mysql_fix_unsigned_and_lob_columns() {
$pbar->update($i, $tablecount, "Converted unsigned/lob columns in MySQL 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 only one section and that course_modules.section points back to it.
*
* Orphaned modules (modules that were not included in any section sequence in this course)
* will be added to their sections (or 0-section if their section is not found) and
* made invisible since they were not accessible at all before this upgrade script.
*
* Note that this script does not remove non-existing modules from section sequences since
* such operation would require much more time.
*/
function upgrade_course_modules_sequences() {
global $DB;

$affectedcourses = array();
// Step 1. 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);
}
$affectedcourses[$cm->course] = true;
}
// 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);

// Step 2. Find all modules that are listed in sequence of another section or listed in sequence of their section twice.
$sequenceconcat = $DB->sql_concat("','", "s.sequence", "','");
$moduleconcat = $DB->sql_concat("'%,'", "m.id", "',%'");
$moduleconcatdup1 = $DB->sql_concat("'%,'", "m.id", "','", "m.id", "',%'");
$moduleconcatdup2 = $DB->sql_concat("'%,'", "m.id", "',%,'", "m.id", "',%'");
$sql = "SELECT m.id, m.course, m.section AS modulesectionid,
s.id AS sectionid, s.sequence AS sectionsequence, s.section AS sectionsectionnum,
ms.section AS modulesectionnum, ms.sequence AS modulesectionsequence
FROM {course_modules} m JOIN {course_sections} s
ON m.course = s.course AND
(
(m.section <> s.id AND $sequenceconcat LIKE $moduleconcat)
OR
(m.section = s.id AND $sequenceconcat LIKE $moduleconcatdup1)
OR
(m.section = s.id AND $sequenceconcat LIKE $moduleconcatdup2)
)
JOIN {course_sections} ms ON ms.id = m.section
ORDER BY m.course, m.id, m.section DESC";
$rs = $DB->get_recordset_sql($sql);
$updatedsequences = array();
$correctmodulesections = array();
foreach ($rs as $cm) {
$incorrectsectionid = $cm->sectionid;
$incorrectsequence = $cm->sectionsequence;
if (!isset($correctmodulesections[$cm->id])) {
// Function get_fast_modinfo() believes that the section with the biggest sectionnum is the correct one.
// Let's correct everything else to match with how course is displayed to the students.
if ($cm->modulesectionnum > $cm->sectionsectionnum) {
$correctmodulesections[$cm->id] = $cm->modulesectionid;
} else {
$correctmodulesections[$cm->id] = $cm->sectionid;
// oops our module points to the wrong section.
$DB->update_record('course_modules', array('id' => $cm->id,
'section' => $correctmodulesections[$cm->id]));
$incorrectsectionid = $cm->modulesectionid;
$incorrectsequence = $cm->modulesectionsequence;
}
}
if (isset($updatedsequences[$incorrectsectionid])) {
$sequence = $updatedsequences[$incorrectsectionid];
} else {
$sequence = preg_split('/,/', $incorrectsequence);
}
if ($correctmodulesections[$cm->id] <> $incorrectsectionid) {
// Remove all occurences of module id from section sequence.
$sequence = array_diff($sequence, array($cm->id));
} else {
// Remove all occurences of module id from section sequence except for the first one.
if (($idx = array_search($cm->id, $sequence)) !== false) {
$firstchunk = array_splice($sequence, 0, $idx+1);
$sequence = array_merge($firstchunk, array_diff($sequence, array($cm->id)));
}
}
$updatedsequences[$incorrectsectionid] = array_values($sequence);
$DB->update_record('course_sections', array('id' => $incorrectsectionid,
'sequence' => join(',', $sequence)));
$affectedcourses[$cm->course] = true;
}
$rs->close();

// Reset course cache for affected courses.
if (!empty($affectedcourses)) {
list($sql, $params) = $DB->get_in_or_equal(array_keys($affectedcourses));
$DB->execute("UPDATE {course} SET modinfo = null WHERE id ".$sql, $params);
}
}

0 comments on commit ba5ecbc

Please sign in to comment.