/**
* Reads the install.xml files for Moodle core and modules and returns an array of
* xmldb_structure object with xmldb_table from these files.
* @return xmldb_structure schema from install.xml files
*/
public function get_install_xml_schema()
{
global $CFG;
require_once $CFG->libdir . '/adminlib.php';
$schema = new xmldb_structure('export');
$schema->setVersion($CFG->version);
$dbdirs = get_db_directories();
foreach ($dbdirs as $dbdir) {
$xmldb_file = new xmldb_file($dbdir . '/install.xml');
if (!$xmldb_file->fileExists() or !$xmldb_file->loadXMLStructure()) {
continue;
}
$structure = $xmldb_file->getStructure();
$tables = $structure->getTables();
foreach ($tables as $table) {
$table->setPrevious(null);
$table->setNext(null);
$schema->addTable($table);
}
}
return $schema;
}
function cleanup()
{
global $DB;
$dbman = $DB->get_manager();
$tablename = student::TABLE;
$tempname = $tablename . '_temp';
$table = new xmldb_table($tempname);
if ($dbman->table_exists($table)) {
if (!$dbman->drop_table($table)) {
mtrace(' <<< Could not remove temporary table: ' . $tempname);
exit;
}
}
// Create a temporary table by reading in the XMLDB file that defines the student enrolment table
$xmldb_file = new xmldb_file(elispm::file('db/install.xml'));
if (!$xmldb_file->fileExists() or !$xmldb_file->loadXMLStructure()) {
continue;
}
$structure = $xmldb_file->getStructure();
$tables = $structure->getTables();
foreach ($tables as $table) {
if ($table->getName() == $tablename) {
$xml_temptable = $table;
$xml_temptable->setName($tempname);
$xml_temptable->setPrevious(null);
$xml_temptable->setNext(null);
$tempstructure = new xmldb_structure('temp');
$tempstructure->addTable($xml_temptable);
try {
$dbman->install_from_xmldb_structure($tempstructure);
} catch (ddl_change_structure_exception $e) {
mtrace(' <<< Could not create temporary table: ' . $tempname);
exit;
}
mtrace(' >>> Created temporary table: ' . $tempname);
}
}
$xml_table = new xmldb_table($tablename);
// Step 1. -- attempt to move unique values into the temporary table in a way that should leave some duplicates but
// will remove the vast majority of the them
$sql = "INSERT INTO {{$tempname}}\n SELECT id, classid, userid, enrolmenttime, MIN(completetime) AS completetime, endtime, completestatusid,\n grade, credits, locked\n FROM {{$tablename}}\n GROUP BY classid, userid, completestatusid, grade, credits, locked";
try {
$DB->execute($sql);
} catch (dml_exception $e) {
mtrace(' <<< Could not move duplicate records from: ' . $tablename . ' into: ' . $tempname);
exit;
}
mtrace(' >>> Moved duplicate records from: ' . $tablename . ' into: ' . $tempname);
// Step 2. -- detect if we still have any duplicates remaining
$sql = "SELECT id, COUNT(*) AS count, classid, userid, enrolmenttime, completetime, completestatusid, grade, credits, locked\n FROM {{$tempname}}\n GROUP BY classid, userid\n ORDER BY count DESC, classid ASC, userid ASC";
if ($dupcount = $DB->get_records_sql($sql, array(), 0, 1)) {
$dupe = current($dupcount);
if ($dupe->count > 1) {
mtrace(' <<< Duplicate records still exist in temporary table');
} else {
mtrace(' >>> No duplicate records exist in temporary table');
}
}
// Step 3. -- at this point duplicate data was found, so we will need to process each record in turn to find the first
// legitimate record that should be kept
if ($rs = $DB->get_recordset_sql($sql)) {
foreach ($rs as $dupe) {
if ($dupe->count <= 1) {
continue;
}
$classid = $dupe->classid;
$userid = $dupe->userid;
$goodid = 0;
// The ID of the record we will keep
// Find the record marked "complete" or "failed" and locked with the earliest completion time
$sql2 = "SELECT id, completestatusid, grade locked\n FROM {{$tempname}}\n WHERE userid = {$userid}\n AND classid = {$classid}\n ORDER BY completetime ASC, completestatusid ASC, locked ASC";
if ($rs2 = $DB->get_recordset_sql($sql2)) {
foreach ($rs2 as $rec) {
// Store the last record ID just in case we need it for cleanup
$lastid = $rec->id;
// Don't bother looking at remaining records if we have found a record to keep
if (!empty($goodid)) {
continue;
}
if ($rec->completestatusid != 0 && ($rec->locked = 1)) {
$goodid = $rec->id;
}
}
$rs2->close();
// We need to make sure we have a record ID to keep, if we found no "complete" and locked
// records, let's just keep the last record we saw
if (empty($goodid)) {
$goodid = $lastid;
}
$select = 'classid = ' . $classid . ' AND userid = ' . $userid . ' AND id != ' . $goodid;
}
// If we have some records to clean up, let's do that now
if (!empty($select)) {
$status = true;
try {
$DB->delete_records_select($tempname, $select);
} catch (dml_exception $e) {
mtrace(' <<< Could not clean up duplicate ' . $tempname . ' records for userid = ' . $userid . ', classid = ' . $classid);
$status = false;
}
if ($status) {
mtrace(' >>> Cleaned up duplicate ' . $tempname . ' records for userid = ' . $userid . ', classid = ' . $classid);
}
}
}
$rs->close();
}
// Step 4. -- drop the table containing duplicate values and rename the temporary table to take it's place
try {
$dbman->drop_table($xml_table);
} catch (ddl_change_structure_exception $e) {
mtrace(' <<< Could not drop table: ' . $tablename);
exit;
}
mtrace(' >>> Successfully dropped table: ' . $tablename);
// Rename the temporary table to allow it to replace the real table
try {
$dbman->rename_table($xml_temptable, $tablename);
} catch (ddl_change_structure_exception $e) {
mtrace(' <<< Could not rename table: ' . $tempname . ' to: ' . $tablename);
exit;
}
mtrace(' >>> Successfully renamed table: ' . $tempname . ' to: ' . $tablename);
}
