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See Release Notes

  • Bug fixes for general core bugs in 3.11.x will end 14 Nov 2022 (12 months plus 6 months extension).
  • Bug fixes for security issues in 3.11.x will end 13 Nov 2023 (18 months plus 12 months extension).
  • PHP version: minimum PHP 7.3.0 Note: minimum PHP version has increased since Moodle 3.10. PHP 7.4.x is supported too.
/lib/ -> datalib.php (source)

Differences Between: [Versions 310 and 311] [Versions 311 and 401] [Versions 38 and 311] [Versions 39 and 311]

   1  <?php
   2  // This file is part of Moodle - http://moodle.org/
   3  //
   4  // Moodle is free software: you can redistribute it and/or modify
   5  // it under the terms of the GNU General Public License as published by
   6  // the Free Software Foundation, either version 3 of the License, or
   7  // (at your option) any later version.
   8  //
   9  // Moodle is distributed in the hope that it will be useful,
  10  // but WITHOUT ANY WARRANTY; without even the implied warranty of
  11  // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12  // GNU General Public License for more details.
  13  //
  14  // You should have received a copy of the GNU General Public License
  15  // along with Moodle.  If not, see <http://www.gnu.org/licenses/>.
  16  
  17  /**
  18   * Library of functions for database manipulation.
  19   *
  20   * Other main libraries:
  21   * - weblib.php - functions that produce web output
  22   * - moodlelib.php - general-purpose Moodle functions
  23   *
  24   * @package    core
  25   * @copyright  1999 onwards Martin Dougiamas  {@link http://moodle.com}
  26   * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
  27   */
  28  
  29  defined('MOODLE_INTERNAL') || die();
  30  
  31  /**
  32   * The maximum courses in a category
  33   * MAX_COURSES_IN_CATEGORY * MAX_COURSE_CATEGORIES must not be more than max integer!
  34   */
  35  define('MAX_COURSES_IN_CATEGORY', 10000);
  36  
  37  /**
  38    * The maximum number of course categories
  39    * MAX_COURSES_IN_CATEGORY * MAX_COURSE_CATEGORIES must not be more than max integer!
  40    */
  41  define('MAX_COURSE_CATEGORIES', 10000);
  42  
  43  /**
  44   * Number of seconds to wait before updating lastaccess information in DB.
  45   *
  46   * We allow overwrites from config.php, useful to ensure coherence in performance
  47   * tests results.
  48   *
  49   * Note: For web service requests in the external_tokens field, we use a different constant
  50   * webservice::TOKEN_LASTACCESS_UPDATE_SECS.
  51   */
  52  if (!defined('LASTACCESS_UPDATE_SECS')) {
  53      define('LASTACCESS_UPDATE_SECS', 60);
  54  }
  55  
  56  /**
  57   * Returns $user object of the main admin user
  58   *
  59   * @static stdClass $mainadmin
  60   * @return stdClass {@link $USER} record from DB, false if not found
  61   */
  62  function get_admin() {
  63      global $CFG, $DB;
  64  
  65      static $mainadmin = null;
  66      static $prevadmins = null;
  67  
  68      if (empty($CFG->siteadmins)) {
  69          // Should not happen on an ordinary site.
  70          // It does however happen during unit tests.
  71          return false;
  72      }
  73  
  74      if (isset($mainadmin) and $prevadmins === $CFG->siteadmins) {
  75          return clone($mainadmin);
  76      }
  77  
  78      $mainadmin = null;
  79  
  80      foreach (explode(',', $CFG->siteadmins) as $id) {
  81          if ($user = $DB->get_record('user', array('id'=>$id, 'deleted'=>0))) {
  82              $mainadmin = $user;
  83              break;
  84          }
  85      }
  86  
  87      if ($mainadmin) {
  88          $prevadmins = $CFG->siteadmins;
  89          return clone($mainadmin);
  90      } else {
  91          // this should not happen
  92          return false;
  93      }
  94  }
  95  
  96  /**
  97   * Returns list of all admins, using 1 DB query
  98   *
  99   * @return array
 100   */
 101  function get_admins() {
 102      global $DB, $CFG;
 103  
 104      if (empty($CFG->siteadmins)) {  // Should not happen on an ordinary site
 105          return array();
 106      }
 107  
 108      $sql = "SELECT u.*
 109                FROM {user} u
 110               WHERE u.deleted = 0 AND u.id IN ($CFG->siteadmins)";
 111  
 112      // We want the same order as in $CFG->siteadmins.
 113      $records = $DB->get_records_sql($sql);
 114      $admins = array();
 115      foreach (explode(',', $CFG->siteadmins) as $id) {
 116          $id = (int)$id;
 117          if (!isset($records[$id])) {
 118              // User does not exist, this should not happen.
 119              continue;
 120          }
 121          $admins[$records[$id]->id] = $records[$id];
 122      }
 123  
 124      return $admins;
 125  }
 126  
 127  /**
 128   * Search through course users
 129   *
 130   * If $coursid specifies the site course then this function searches
 131   * through all undeleted and confirmed users
 132   *
 133   * @global object
 134   * @uses SITEID
 135   * @uses SQL_PARAMS_NAMED
 136   * @uses CONTEXT_COURSE
 137   * @param int $courseid The course in question.
 138   * @param int $groupid The group in question.
 139   * @param string $searchtext The string to search for
 140   * @param string $sort A field to sort by
 141   * @param array $exceptions A list of IDs to ignore, eg 2,4,5,8,9,10
 142   * @return array
 143   */
 144  function search_users($courseid, $groupid, $searchtext, $sort='', array $exceptions=null) {
 145      global $DB;
 146  
 147      $fullname  = $DB->sql_fullname('u.firstname', 'u.lastname');
 148  
 149      if (!empty($exceptions)) {
 150          list($exceptions, $params) = $DB->get_in_or_equal($exceptions, SQL_PARAMS_NAMED, 'ex', false);
 151          $except = "AND u.id $exceptions";
 152      } else {
 153          $except = "";
 154          $params = array();
 155      }
 156  
 157      if (!empty($sort)) {
 158          $order = "ORDER BY $sort";
 159      } else {
 160          $order = "";
 161      }
 162  
 163      $select = "u.deleted = 0 AND u.confirmed = 1 AND (".$DB->sql_like($fullname, ':search1', false)." OR ".$DB->sql_like('u.email', ':search2', false).")";
 164      $params['search1'] = "%$searchtext%";
 165      $params['search2'] = "%$searchtext%";
 166  
 167      if (!$courseid or $courseid == SITEID) {
 168          $sql = "SELECT u.id, u.firstname, u.lastname, u.email
 169                    FROM {user} u
 170                   WHERE $select
 171                         $except
 172                  $order";
 173          return $DB->get_records_sql($sql, $params);
 174  
 175      } else {
 176          if ($groupid) {
 177              $sql = "SELECT u.id, u.firstname, u.lastname, u.email
 178                        FROM {user} u
 179                        JOIN {groups_members} gm ON gm.userid = u.id
 180                       WHERE $select AND gm.groupid = :groupid
 181                             $except
 182                       $order";
 183              $params['groupid'] = $groupid;
 184              return $DB->get_records_sql($sql, $params);
 185  
 186          } else {
 187              $context = context_course::instance($courseid);
 188  
 189              // We want to query both the current context and parent contexts.
 190              list($relatedctxsql, $relatedctxparams) = $DB->get_in_or_equal($context->get_parent_context_ids(true), SQL_PARAMS_NAMED, 'relatedctx');
 191  
 192              $sql = "SELECT u.id, u.firstname, u.lastname, u.email
 193                        FROM {user} u
 194                        JOIN {role_assignments} ra ON ra.userid = u.id
 195                       WHERE $select AND ra.contextid $relatedctxsql
 196                             $except
 197                      $order";
 198              $params = array_merge($params, $relatedctxparams);
 199              return $DB->get_records_sql($sql, $params);
 200          }
 201      }
 202  }
 203  
 204  /**
 205   * Returns SQL used to search through user table to find users (in a query
 206   * which may also join and apply other conditions).
 207   *
 208   * You can combine this SQL with an existing query by adding 'AND $sql' to the
 209   * WHERE clause of your query (where $sql is the first element in the array
 210   * returned by this function), and merging in the $params array to the parameters
 211   * of your query (where $params is the second element). Your query should use
 212   * named parameters such as :param, rather than the question mark style.
 213   *
 214   * There are examples of basic usage in the unit test for this function.
 215   *
 216   * @param string $search the text to search for (empty string = find all)
 217   * @param string $u the table alias for the user table in the query being
 218   *     built. May be ''.
 219   * @param bool $searchanywhere If true (default), searches in the middle of
 220   *     names, otherwise only searches at start
 221   * @param array $extrafields Array of extra user fields to include in search, must be prefixed with table alias if they are not in
 222   *     the user table.
 223   * @param array $exclude Array of user ids to exclude (empty = don't exclude)
 224   * @param array $includeonly If specified, only returns users that have ids
 225   *     incldued in this array (empty = don't restrict)
 226   * @return array an array with two elements, a fragment of SQL to go in the
 227   *     where clause the query, and an associative array containing any required
 228   *     parameters (using named placeholders).
 229   */
 230  function users_search_sql(string $search, string $u = 'u', bool $searchanywhere = true, array $extrafields = [],
 231          array $exclude = null, array $includeonly = null): array {
 232      global $DB, $CFG;
 233      $params = array();
 234      $tests = array();
 235  
 236      if ($u) {
 237          $u .= '.';
 238      }
 239  
 240      // If we have a $search string, put a field LIKE '$search%' condition on each field.
 241      if ($search) {
 242          $conditions = array(
 243              $DB->sql_fullname($u . 'firstname', $u . 'lastname'),
 244              $conditions[] = $u . 'lastname'
 245          );
 246          foreach ($extrafields as $field) {
 247              // Add the table alias for the user table if the field doesn't already have an alias.
 248              $conditions[] = strpos($field, '.') !== false ? $field : $u . $field;
 249          }
 250          if ($searchanywhere) {
 251              $searchparam = '%' . $search . '%';
 252          } else {
 253              $searchparam = $search . '%';
 254          }
 255          $i = 0;
 256          foreach ($conditions as $key => $condition) {
 257              $conditions[$key] = $DB->sql_like($condition, ":con{$i}00", false, false);
 258              $params["con{$i}00"] = $searchparam;
 259              $i++;
 260          }
 261          $tests[] = '(' . implode(' OR ', $conditions) . ')';
 262      }
 263  
 264      // Add some additional sensible conditions.
 265      $tests[] = $u . "id <> :guestid";
 266      $params['guestid'] = $CFG->siteguest;
 267      $tests[] = $u . 'deleted = 0';
 268      $tests[] = $u . 'confirmed = 1';
 269  
 270      // If we are being asked to exclude any users, do that.
 271      if (!empty($exclude)) {
 272          list($usertest, $userparams) = $DB->get_in_or_equal($exclude, SQL_PARAMS_NAMED, 'ex', false);
 273          $tests[] = $u . 'id ' . $usertest;
 274          $params = array_merge($params, $userparams);
 275      }
 276  
 277      // If we are validating a set list of userids, add an id IN (...) test.
 278      if (!empty($includeonly)) {
 279          list($usertest, $userparams) = $DB->get_in_or_equal($includeonly, SQL_PARAMS_NAMED, 'val');
 280          $tests[] = $u . 'id ' . $usertest;
 281          $params = array_merge($params, $userparams);
 282      }
 283  
 284      // In case there are no tests, add one result (this makes it easier to combine
 285      // this with an existing query as you can always add AND $sql).
 286      if (empty($tests)) {
 287          $tests[] = '1 = 1';
 288      }
 289  
 290      // Combing the conditions and return.
 291      return array(implode(' AND ', $tests), $params);
 292  }
 293  
 294  
 295  /**
 296   * This function generates the standard ORDER BY clause for use when generating
 297   * lists of users. If you don't have a reason to use a different order, then
 298   * you should use this method to generate the order when displaying lists of users.
 299   *
 300   * If the optional $search parameter is passed, then exact matches to the search
 301   * will be sorted first. For example, suppose you have two users 'Al Zebra' and
 302   * 'Alan Aardvark'. The default sort is Alan, then Al. If, however, you search for
 303   * 'Al', then Al will be listed first. (With two users, this is not a big deal,
 304   * but with thousands of users, it is essential.)
 305   *
 306   * The list of fields scanned for exact matches are:
 307   *  - firstname
 308   *  - lastname
 309   *  - $DB->sql_fullname
 310   *  - those returned by \core_user\fields::get_identity_fields or those included in $customfieldmappings
 311   *
 312   * If named parameters are used (which is the default, and highly recommended),
 313   * then the parameter names are like :usersortexactN, where N is an int.
 314   *
 315   * The simplest possible example use is:
 316   * list($sort, $params) = users_order_by_sql();
 317   * $sql = 'SELECT * FROM {users} ORDER BY ' . $sort;
 318   *
 319   * A more complex example, showing that this sort can be combined with other sorts:
 320   * list($sort, $sortparams) = users_order_by_sql('u');
 321   * $sql = "SELECT g.id AS groupid, gg.groupingid, u.id AS userid, u.firstname, u.lastname, u.idnumber, u.username
 322   *           FROM {groups} g
 323   *      LEFT JOIN {groupings_groups} gg ON g.id = gg.groupid
 324   *      LEFT JOIN {groups_members} gm ON g.id = gm.groupid
 325   *      LEFT JOIN {user} u ON gm.userid = u.id
 326   *          WHERE g.courseid = :courseid $groupwhere $groupingwhere
 327   *       ORDER BY g.name, $sort";
 328   * $params += $sortparams;
 329   *
 330   * An example showing the use of $search:
 331   * list($sort, $sortparams) = users_order_by_sql('u', $search, $this->get_context());
 332   * $order = ' ORDER BY ' . $sort;
 333   * $params += $sortparams;
 334   * $availableusers = $DB->get_records_sql($fields . $sql . $order, $params, $page*$perpage, $perpage);
 335   *
 336   * @param string $usertablealias (optional) any table prefix for the {users} table. E.g. 'u'.
 337   * @param string $search (optional) a current search string. If given,
 338   *      any exact matches to this string will be sorted first.
 339   * @param context|null $context the context we are in. Used by \core_user\fields::get_identity_fields.
 340   *      Defaults to $PAGE->context.
 341   * @param array $customfieldmappings associative array of mappings for custom fields returned by \core_user\fields::get_sql.
 342   * @return array with two elements:
 343   *      string SQL fragment to use in the ORDER BY clause. For example, "firstname, lastname".
 344   *      array of parameters used in the SQL fragment. If $search is not given, this is guaranteed to be an empty array.
 345   */
 346  function users_order_by_sql(string $usertablealias = '', string $search = null, context $context = null,
 347          array $customfieldmappings = []) {
 348      global $DB, $PAGE;
 349  
 350      if ($usertablealias) {
 351          $tableprefix = $usertablealias . '.';
 352      } else {
 353          $tableprefix = '';
 354      }
 355  
 356      $sort = "{$tableprefix}lastname, {$tableprefix}firstname, {$tableprefix}id";
 357      $params = array();
 358  
 359      if (!$search) {
 360          return array($sort, $params);
 361      }
 362  
 363      if (!$context) {
 364          $context = $PAGE->context;
 365      }
 366  
 367      $exactconditions = array();
 368      $paramkey = 'usersortexact1';
 369  
 370      $exactconditions[] = $DB->sql_fullname($tableprefix . 'firstname', $tableprefix  . 'lastname') .
 371              ' = :' . $paramkey;
 372      $params[$paramkey] = $search;
 373      $paramkey++;
 374  
 375      if ($customfieldmappings) {
 376          $fieldstocheck = array_merge([$tableprefix . 'firstname', $tableprefix . 'lastname'], array_values($customfieldmappings));
 377      } else {
 378          $fieldstocheck = array_merge(['firstname', 'lastname'], \core_user\fields::get_identity_fields($context, false));
 379          $fieldstocheck = array_map(function($field) use ($tableprefix) {
 380              return $tableprefix . $field;
 381          }, $fieldstocheck);
 382      }
 383  
 384      foreach ($fieldstocheck as $key => $field) {
 385          $exactconditions[] = 'LOWER(' . $field . ') = LOWER(:' . $paramkey . ')';
 386          $params[$paramkey] = $search;
 387          $paramkey++;
 388      }
 389  
 390      $sort = 'CASE WHEN ' . implode(' OR ', $exactconditions) .
 391              ' THEN 0 ELSE 1 END, ' . $sort;
 392  
 393      return array($sort, $params);
 394  }
 395  
 396  /**
 397   * Returns a subset of users
 398   *
 399   * @global object
 400   * @uses DEBUG_DEVELOPER
 401   * @uses SQL_PARAMS_NAMED
 402   * @param bool $get If false then only a count of the records is returned
 403   * @param string $search A simple string to search for
 404   * @param bool $confirmed A switch to allow/disallow unconfirmed users
 405   * @param array $exceptions A list of IDs to ignore, eg 2,4,5,8,9,10
 406   * @param string $sort A SQL snippet for the sorting criteria to use
 407   * @param string $firstinitial Users whose first name starts with $firstinitial
 408   * @param string $lastinitial Users whose last name starts with $lastinitial
 409   * @param string $page The page or records to return
 410   * @param string $recordsperpage The number of records to return per page
 411   * @param string $fields A comma separated list of fields to be returned from the chosen table.
 412   * @return array|int|bool  {@link $USER} records unless get is false in which case the integer count of the records found is returned.
 413   *                        False is returned if an error is encountered.
 414   */
 415  function get_users($get=true, $search='', $confirmed=false, array $exceptions=null, $sort='firstname ASC',
 416                     $firstinitial='', $lastinitial='', $page='', $recordsperpage='', $fields='*', $extraselect='', array $extraparams=null) {
 417      global $DB, $CFG;
 418  
 419      if ($get && !$recordsperpage) {
 420          debugging('Call to get_users with $get = true no $recordsperpage limit. ' .
 421                  'On large installations, this will probably cause an out of memory error. ' .
 422                  'Please think again and change your code so that it does not try to ' .
 423                  'load so much data into memory.', DEBUG_DEVELOPER);
 424      }
 425  
 426      $fullname  = $DB->sql_fullname();
 427  
 428      $select = " id <> :guestid AND deleted = 0";
 429      $params = array('guestid'=>$CFG->siteguest);
 430  
 431      if (!empty($search)){
 432          $search = trim($search);
 433          $select .= " AND (".$DB->sql_like($fullname, ':search1', false)." OR ".$DB->sql_like('email', ':search2', false)." OR username = :search3)";
 434          $params['search1'] = "%$search%";
 435          $params['search2'] = "%$search%";
 436          $params['search3'] = "$search";
 437      }
 438  
 439      if ($confirmed) {
 440          $select .= " AND confirmed = 1";
 441      }
 442  
 443      if ($exceptions) {
 444          list($exceptions, $eparams) = $DB->get_in_or_equal($exceptions, SQL_PARAMS_NAMED, 'ex', false);
 445          $params = $params + $eparams;
 446          $select .= " AND id $exceptions";
 447      }
 448  
 449      if ($firstinitial) {
 450          $select .= " AND ".$DB->sql_like('firstname', ':fni', false, false);
 451          $params['fni'] = "$firstinitial%";
 452      }
 453      if ($lastinitial) {
 454          $select .= " AND ".$DB->sql_like('lastname', ':lni', false, false);
 455          $params['lni'] = "$lastinitial%";
 456      }
 457  
 458      if ($extraselect) {
 459          $select .= " AND $extraselect";
 460          $params = $params + (array)$extraparams;
 461      }
 462  
 463      if ($get) {
 464          return $DB->get_records_select('user', $select, $params, $sort, $fields, $page, $recordsperpage);
 465      } else {
 466          return $DB->count_records_select('user', $select, $params);
 467      }
 468  }
 469  
 470  
 471  /**
 472   * Return filtered (if provided) list of users in site, except guest and deleted users.
 473   *
 474   * @param string $sort An SQL field to sort by
 475   * @param string $dir The sort direction ASC|DESC
 476   * @param int $page The page or records to return
 477   * @param int $recordsperpage The number of records to return per page
 478   * @param string $search A simple string to search for
 479   * @param string $firstinitial Users whose first name starts with $firstinitial
 480   * @param string $lastinitial Users whose last name starts with $lastinitial
 481   * @param string $extraselect An additional SQL select statement to append to the query
 482   * @param array $extraparams Additional parameters to use for the above $extraselect
 483   * @param stdClass $extracontext If specified, will include user 'extra fields'
 484   *   as appropriate for current user and given context
 485   * @return array Array of {@link $USER} records
 486   */
 487  function get_users_listing($sort='lastaccess', $dir='ASC', $page=0, $recordsperpage=0,
 488                             $search='', $firstinitial='', $lastinitial='', $extraselect='',
 489                             array $extraparams=null, $extracontext = null) {
 490      global $DB, $CFG;
 491  
 492      $fullname  = $DB->sql_fullname();
 493  
 494      $select = "deleted <> 1 AND u.id <> :guestid";
 495      $params = array('guestid' => $CFG->siteguest);
 496  
 497      if (!empty($search)) {
 498          $search = trim($search);
 499          $select .= " AND (". $DB->sql_like($fullname, ':search1', false, false).
 500                     " OR ". $DB->sql_like('email', ':search2', false, false).
 501                     " OR username = :search3)";
 502          $params['search1'] = "%$search%";
 503          $params['search2'] = "%$search%";
 504          $params['search3'] = "$search";
 505      }
 506  
 507      if ($firstinitial) {
 508          $select .= " AND ". $DB->sql_like('firstname', ':fni', false, false);
 509          $params['fni'] = "$firstinitial%";
 510      }
 511      if ($lastinitial) {
 512          $select .= " AND ". $DB->sql_like('lastname', ':lni', false, false);
 513          $params['lni'] = "$lastinitial%";
 514      }
 515  
 516      if ($extraselect) {
 517          // The extra WHERE clause may refer to the 'id' column which can now be ambiguous because we
 518          // changed the query to include joins, so replace any 'id' that is on its own (no alias)
 519          // with 'u.id'.
 520          $extraselect = preg_replace('~([ =]|^)id([ =]|$)~', '$1u.id$2', $extraselect);
 521          $select .= " AND $extraselect";
 522          $params = $params + (array)$extraparams;
 523      }
 524  
 525      // If a context is specified, get extra user fields that the current user
 526      // is supposed to see, otherwise just get the name fields.
 527      $userfields = \core_user\fields::for_name();
 528      if ($extracontext) {
 529          $userfields->with_identity($extracontext, true);
 530      }
 531  
 532      $userfields->excluding('id');
 533      $userfields->including('username', 'email', 'city', 'country', 'lastaccess', 'confirmed', 'mnethostid', 'suspended');
 534      ['selects' => $selects, 'joins' => $joins, 'params' => $joinparams, 'mappings' => $mappings] =
 535              (array)$userfields->get_sql('u', true);
 536  
 537      if ($sort) {
 538          $orderbymap = $mappings;
 539          $orderbymap['default'] = 'lastaccess';
 540          $sort = get_safe_orderby($orderbymap, $sort, $dir);
 541      }
 542  
 543      // warning: will return UNCONFIRMED USERS
 544      return $DB->get_records_sql("SELECT u.id $selects
 545                                     FROM {user} u
 546                                          $joins
 547                                    WHERE $select
 548                                    $sort", array_merge($params, $joinparams), $page, $recordsperpage);
 549  
 550  }
 551  
 552  
 553  /**
 554   * Full list of users that have confirmed their accounts.
 555   *
 556   * @global object
 557   * @return array of unconfirmed users
 558   */
 559  function get_users_confirmed() {
 560      global $DB, $CFG;
 561      return $DB->get_records_sql("SELECT *
 562                                     FROM {user}
 563                                    WHERE confirmed = 1 AND deleted = 0 AND id <> ?", array($CFG->siteguest));
 564  }
 565  
 566  
 567  /// OTHER SITE AND COURSE FUNCTIONS /////////////////////////////////////////////
 568  
 569  
 570  /**
 571   * Returns $course object of the top-level site.
 572   *
 573   * @return object A {@link $COURSE} object for the site, exception if not found
 574   */
 575  function get_site() {
 576      global $SITE, $DB;
 577  
 578      if (!empty($SITE->id)) {   // We already have a global to use, so return that
 579          return $SITE;
 580      }
 581  
 582      if ($course = $DB->get_record('course', array('category'=>0))) {
 583          return $course;
 584      } else {
 585          // course table exists, but the site is not there,
 586          // unfortunately there is no automatic way to recover
 587          throw new moodle_exception('nosite', 'error');
 588      }
 589  }
 590  
 591  /**
 592   * Gets a course object from database. If the course id corresponds to an
 593   * already-loaded $COURSE or $SITE object, then the loaded object will be used,
 594   * saving a database query.
 595   *
 596   * If it reuses an existing object, by default the object will be cloned. This
 597   * means you can modify the object safely without affecting other code.
 598   *
 599   * @param int $courseid Course id
 600   * @param bool $clone If true (default), makes a clone of the record
 601   * @return stdClass A course object
 602   * @throws dml_exception If not found in database
 603   */
 604  function get_course($courseid, $clone = true) {
 605      global $DB, $COURSE, $SITE;
 606      if (!empty($COURSE->id) && $COURSE->id == $courseid) {
 607          return $clone ? clone($COURSE) : $COURSE;
 608      } else if (!empty($SITE->id) && $SITE->id == $courseid) {
 609          return $clone ? clone($SITE) : $SITE;
 610      } else {
 611          return $DB->get_record('course', array('id' => $courseid), '*', MUST_EXIST);
 612      }
 613  }
 614  
 615  /**
 616   * Returns list of courses, for whole site, or category
 617   *
 618   * Returns list of courses, for whole site, or category
 619   * Important: Using c.* for fields is extremely expensive because
 620   *            we are using distinct. You almost _NEVER_ need all the fields
 621   *            in such a large SELECT
 622   *
 623   * Consider using core_course_category::get_courses()
 624   * or core_course_category::search_courses() instead since they use caching.
 625   *
 626   * @global object
 627   * @global object
 628   * @global object
 629   * @uses CONTEXT_COURSE
 630   * @param string|int $categoryid Either a category id or 'all' for everything
 631   * @param string $sort A field and direction to sort by
 632   * @param string $fields The additional fields to return (note that "id, category, visible" are always present)
 633   * @return array Array of courses
 634   */
 635  function get_courses($categoryid="all", $sort="c.sortorder ASC", $fields="c.*") {
 636  
 637      global $USER, $CFG, $DB;
 638  
 639      $params = array();
 640  
 641      if ($categoryid !== "all" && is_numeric($categoryid)) {
 642          $categoryselect = "WHERE c.category = :catid";
 643          $params['catid'] = $categoryid;
 644      } else {
 645          $categoryselect = "";
 646      }
 647  
 648      if (empty($sort)) {
 649          $sortstatement = "";
 650      } else {
 651          $sortstatement = "ORDER BY $sort";
 652      }
 653  
 654      $visiblecourses = array();
 655  
 656      $ccselect = ', ' . context_helper::get_preload_record_columns_sql('ctx');
 657      $ccjoin = "LEFT JOIN {context} ctx ON (ctx.instanceid = c.id AND ctx.contextlevel = :contextlevel)";
 658      $params['contextlevel'] = CONTEXT_COURSE;
 659  
 660      // The fields "id, category, visible" are required in the subsequent loop and must always be present.
 661      if ($fields !== 'c.*') {
 662          $fieldarray = array_merge(
 663              // Split fields on comma + zero or more whitespace, merge with required fields.
 664              preg_split('/,\s*/', $fields), [
 665                  'c.id',
 666                  'c.category',
 667                  'c.visible',
 668              ]
 669          );
 670          $fields = implode(',', array_unique($fieldarray));
 671      }
 672  
 673      $sql = "SELECT $fields $ccselect
 674                FROM {course} c
 675             $ccjoin
 676                $categoryselect
 677                $sortstatement";
 678  
 679      // pull out all course matching the cat
 680      if ($courses = $DB->get_records_sql($sql, $params)) {
 681  
 682          // loop throught them
 683          foreach ($courses as $course) {
 684              context_helper::preload_from_record($course);
 685              if (core_course_category::can_view_course_info($course)) {
 686                  $visiblecourses [$course->id] = $course;
 687              }
 688          }
 689      }
 690      return $visiblecourses;
 691  }
 692  
 693  /**
 694   * A list of courses that match a search
 695   *
 696   * @global object
 697   * @global object
 698   * @param array $searchterms An array of search criteria
 699   * @param string $sort A field and direction to sort by
 700   * @param int $page The page number to get
 701   * @param int $recordsperpage The number of records per page
 702   * @param int $totalcount Passed in by reference.
 703   * @param array $requiredcapabilities Extra list of capabilities used to filter courses
 704   * @param array $searchcond additional search conditions, for example ['c.enablecompletion = :p1']
 705   * @param array $params named parameters for additional search conditions, for example ['p1' => 1]
 706   * @return stdClass[] {@link $COURSE} records
 707   */
 708  function get_courses_search($searchterms, $sort, $page, $recordsperpage, &$totalcount,
 709                              $requiredcapabilities = array(), $searchcond = [], $params = []) {
 710      global $CFG, $DB;
 711  
 712      if ($DB->sql_regex_supported()) {
 713          $REGEXP    = $DB->sql_regex(true);
 714          $NOTREGEXP = $DB->sql_regex(false);
 715      }
 716  
 717      $i = 0;
 718  
 719      // Thanks Oracle for your non-ansi concat and type limits in coalesce. MDL-29912
 720      if ($DB->get_dbfamily() == 'oracle') {
 721          $concat = "(c.summary|| ' ' || c.fullname || ' ' || c.idnumber || ' ' || c.shortname)";
 722      } else {
 723          $concat = $DB->sql_concat("COALESCE(c.summary, '')", "' '", 'c.fullname', "' '", 'c.idnumber', "' '", 'c.shortname');
 724      }
 725  
 726      foreach ($searchterms as $searchterm) {
 727          $i++;
 728  
 729          $NOT = false; /// Initially we aren't going to perform NOT LIKE searches, only MSSQL and Oracle
 730                     /// will use it to simulate the "-" operator with LIKE clause
 731  
 732      /// Under Oracle and MSSQL, trim the + and - operators and perform
 733      /// simpler LIKE (or NOT LIKE) queries
 734          if (!$DB->sql_regex_supported()) {
 735              if (substr($searchterm, 0, 1) == '-') {
 736                  $NOT = true;
 737              }
 738              $searchterm = trim($searchterm, '+-');
 739          }
 740  
 741          // TODO: +- may not work for non latin languages
 742  
 743          if (substr($searchterm,0,1) == '+') {
 744              $searchterm = trim($searchterm, '+-');
 745              $searchterm = preg_quote($searchterm, '|');
 746              $searchcond[] = "$concat $REGEXP :ss$i";
 747              $params['ss'.$i] = "(^|[^a-zA-Z0-9])$searchterm([^a-zA-Z0-9]|$)";
 748  
 749          } else if ((substr($searchterm,0,1) == "-") && (core_text::strlen($searchterm) > 1)) {
 750              $searchterm = trim($searchterm, '+-');
 751              $searchterm = preg_quote($searchterm, '|');
 752              $searchcond[] = "$concat $NOTREGEXP :ss$i";
 753              $params['ss'.$i] = "(^|[^a-zA-Z0-9])$searchterm([^a-zA-Z0-9]|$)";
 754  
 755          } else {
 756              $searchcond[] = $DB->sql_like($concat,":ss$i", false, true, $NOT);
 757              $params['ss'.$i] = "%$searchterm%";
 758          }
 759      }
 760  
 761      if (empty($searchcond)) {
 762          $searchcond = array('1 = 1');
 763      }
 764  
 765      $searchcond = implode(" AND ", $searchcond);
 766  
 767      $courses = array();
 768      $c = 0; // counts how many visible courses we've seen
 769  
 770      // Tiki pagination
 771      $limitfrom = $page * $recordsperpage;
 772      $limitto   = $limitfrom + $recordsperpage;
 773  
 774      $ccselect = ', ' . context_helper::get_preload_record_columns_sql('ctx');
 775      $ccjoin = "LEFT JOIN {context} ctx ON (ctx.instanceid = c.id AND ctx.contextlevel = :contextlevel)";
 776      $params['contextlevel'] = CONTEXT_COURSE;
 777  
 778      $sql = "SELECT c.* $ccselect
 779                FROM {course} c
 780             $ccjoin
 781               WHERE $searchcond AND c.id <> ".SITEID."
 782            ORDER BY $sort";
 783  
 784      $mycourses = enrol_get_my_courses();
 785      $rs = $DB->get_recordset_sql($sql, $params);
 786      foreach($rs as $course) {
 787          // Preload contexts only for hidden courses or courses we need to return.
 788          context_helper::preload_from_record($course);
 789          $coursecontext = context_course::instance($course->id);
 790          if (!array_key_exists($course->id, $mycourses) && !core_course_category::can_view_course_info($course)) {
 791              continue;
 792          }
 793          if (!empty($requiredcapabilities)) {
 794              if (!has_all_capabilities($requiredcapabilities, $coursecontext)) {
 795                  continue;
 796              }
 797          }
 798          // Don't exit this loop till the end
 799          // we need to count all the visible courses
 800          // to update $totalcount
 801          if ($c >= $limitfrom && $c < $limitto) {
 802              $courses[$course->id] = $course;
 803          }
 804          $c++;
 805      }
 806      $rs->close();
 807  
 808      // our caller expects 2 bits of data - our return
 809      // array, and an updated $totalcount
 810      $totalcount = $c;
 811      return $courses;
 812  }
 813  
 814  /**
 815   * Fixes course category and course sortorder, also verifies category and course parents and paths.
 816   * (circular references are not fixed)
 817   *
 818   * @global object
 819   * @global object
 820   * @uses MAX_COURSE_CATEGORIES
 821   * @uses SITEID
 822   * @uses CONTEXT_COURSE
 823   * @return void
 824   */
 825  function fix_course_sortorder() {
 826      global $DB, $SITE;
 827  
 828      //WARNING: this is PHP5 only code!
 829  
 830      // if there are any changes made to courses or categories we will trigger
 831      // the cache events to purge all cached courses/categories data
 832      $cacheevents = array();
 833  
 834      if ($unsorted = $DB->get_records('course_categories', array('sortorder'=>0))) {
 835          //move all categories that are not sorted yet to the end
 836          $DB->set_field('course_categories', 'sortorder',
 837              get_max_courses_in_category() * MAX_COURSE_CATEGORIES, array('sortorder' => 0));
 838          $cacheevents['changesincoursecat'] = true;
 839      }
 840  
 841      $allcats = $DB->get_records('course_categories', null, 'sortorder, id', 'id, sortorder, parent, depth, path');
 842      $topcats    = array();
 843      $brokencats = array();
 844      foreach ($allcats as $cat) {
 845          $sortorder = (int)$cat->sortorder;
 846          if (!$cat->parent) {
 847              while(isset($topcats[$sortorder])) {
 848                  $sortorder++;
 849              }
 850              $topcats[$sortorder] = $cat;
 851              continue;
 852          }
 853          if (!isset($allcats[$cat->parent])) {
 854              $brokencats[] = $cat;
 855              continue;
 856          }
 857          if (!isset($allcats[$cat->parent]->children)) {
 858              $allcats[$cat->parent]->children = array();
 859          }
 860          while(isset($allcats[$cat->parent]->children[$sortorder])) {
 861              $sortorder++;
 862          }
 863          $allcats[$cat->parent]->children[$sortorder] = $cat;
 864      }
 865      unset($allcats);
 866  
 867      // add broken cats to category tree
 868      if ($brokencats) {
 869          $defaultcat = reset($topcats);
 870          foreach ($brokencats as $cat) {
 871              $topcats[] = $cat;
 872          }
 873      }
 874  
 875      // now walk recursively the tree and fix any problems found
 876      $sortorder = 0;
 877      $fixcontexts = array();
 878      if (_fix_course_cats($topcats, $sortorder, 0, 0, '', $fixcontexts)) {
 879          $cacheevents['changesincoursecat'] = true;
 880      }
 881  
 882      // detect if there are "multiple" frontpage courses and fix them if needed
 883      $frontcourses = $DB->get_records('course', array('category'=>0), 'id');
 884      if (count($frontcourses) > 1) {
 885          if (isset($frontcourses[SITEID])) {
 886              $frontcourse = $frontcourses[SITEID];
 887              unset($frontcourses[SITEID]);
 888          } else {
 889              $frontcourse = array_shift($frontcourses);
 890          }
 891          $defaultcat = reset($topcats);
 892          foreach ($frontcourses as $course) {
 893              $DB->set_field('course', 'category', $defaultcat->id, array('id'=>$course->id));
 894              $context = context_course::instance($course->id);
 895              $fixcontexts[$context->id] = $context;
 896              $cacheevents['changesincourse'] = true;
 897          }
 898          unset($frontcourses);
 899      } else {
 900          $frontcourse = reset($frontcourses);
 901      }
 902  
 903      // now fix the paths and depths in context table if needed
 904      if ($fixcontexts) {
 905          foreach ($fixcontexts as $fixcontext) {
 906              $fixcontext->reset_paths(false);
 907          }
 908          context_helper::build_all_paths(false);
 909          unset($fixcontexts);
 910          $cacheevents['changesincourse'] = true;
 911          $cacheevents['changesincoursecat'] = true;
 912      }
 913  
 914      // release memory
 915      unset($topcats);
 916      unset($brokencats);
 917      unset($fixcontexts);
 918  
 919      // fix frontpage course sortorder
 920      if ($frontcourse->sortorder != 1) {
 921          $DB->set_field('course', 'sortorder', 1, array('id'=>$frontcourse->id));
 922          $cacheevents['changesincourse'] = true;
 923      }
 924  
 925      // now fix the course counts in category records if needed
 926      $sql = "SELECT cc.id, cc.coursecount, COUNT(c.id) AS newcount
 927                FROM {course_categories} cc
 928                LEFT JOIN {course} c ON c.category = cc.id
 929            GROUP BY cc.id, cc.coursecount
 930              HAVING cc.coursecount <> COUNT(c.id)";
 931  
 932      if ($updatecounts = $DB->get_records_sql($sql)) {
 933          // categories with more courses than MAX_COURSES_IN_CATEGORY
 934          $categories = array();
 935          foreach ($updatecounts as $cat) {
 936              $cat->coursecount = $cat->newcount;
 937              if ($cat->coursecount >= get_max_courses_in_category()) {
 938                  $categories[] = $cat->id;
 939              }
 940              unset($cat->newcount);
 941              $DB->update_record_raw('course_categories', $cat, true);
 942          }
 943          if (!empty($categories)) {
 944              $str = implode(', ', $categories);
 945              debugging("The number of courses (category id: $str) has reached max number of courses " .
 946                  "in a category (" . get_max_courses_in_category() . "). It will cause a sorting performance issue. " .
 947                  "Please set higher value for \$CFG->maxcoursesincategory in config.php. " .
 948                  "Please also make sure \$CFG->maxcoursesincategory * MAX_COURSE_CATEGORIES less than max integer. " .
 949                  "See tracker issues: MDL-25669 and MDL-69573", DEBUG_DEVELOPER);
 950          }
 951          $cacheevents['changesincoursecat'] = true;
 952      }
 953  
 954      // now make sure that sortorders in course table are withing the category sortorder ranges
 955      $sql = "SELECT DISTINCT cc.id, cc.sortorder
 956                FROM {course_categories} cc
 957                JOIN {course} c ON c.category = cc.id
 958               WHERE c.sortorder < cc.sortorder OR c.sortorder > cc.sortorder + " . get_max_courses_in_category();
 959  
 960      if ($fixcategories = $DB->get_records_sql($sql)) {
 961          //fix the course sortorder ranges
 962          foreach ($fixcategories as $cat) {
 963              $sql = "UPDATE {course}
 964                         SET sortorder = ".$DB->sql_modulo('sortorder', get_max_courses_in_category())." + ?
 965                       WHERE category = ?";
 966              $DB->execute($sql, array($cat->sortorder, $cat->id));
 967          }
 968          $cacheevents['changesincoursecat'] = true;
 969      }
 970      unset($fixcategories);
 971  
 972      // categories having courses with sortorder duplicates or having gaps in sortorder
 973      $sql = "SELECT DISTINCT c1.category AS id , cc.sortorder
 974                FROM {course} c1
 975                JOIN {course} c2 ON c1.sortorder = c2.sortorder
 976                JOIN {course_categories} cc ON (c1.category = cc.id)
 977               WHERE c1.id <> c2.id";
 978      $fixcategories = $DB->get_records_sql($sql);
 979  
 980      $sql = "SELECT cc.id, cc.sortorder, cc.coursecount, MAX(c.sortorder) AS maxsort, MIN(c.sortorder) AS minsort
 981                FROM {course_categories} cc
 982                JOIN {course} c ON c.category = cc.id
 983            GROUP BY cc.id, cc.sortorder, cc.coursecount
 984              HAVING (MAX(c.sortorder) <>  cc.sortorder + cc.coursecount) OR (MIN(c.sortorder) <>  cc.sortorder + 1)";
 985      $gapcategories = $DB->get_records_sql($sql);
 986  
 987      foreach ($gapcategories as $cat) {
 988          if (isset($fixcategories[$cat->id])) {
 989              // duplicates detected already
 990  
 991          } else if ($cat->minsort == $cat->sortorder and $cat->maxsort == $cat->sortorder + $cat->coursecount - 1) {
 992              // easy - new course inserted with sortorder 0, the rest is ok
 993              $sql = "UPDATE {course}
 994                         SET sortorder = sortorder + 1
 995                       WHERE category = ?";
 996              $DB->execute($sql, array($cat->id));
 997  
 998          } else {
 999              // it needs full resorting
1000              $fixcategories[$cat->id] = $cat;
1001          }
1002          $cacheevents['changesincourse'] = true;
1003      }
1004      unset($gapcategories);
1005  
1006      // fix course sortorders in problematic categories only
1007      foreach ($fixcategories as $cat) {
1008          $i = 1;
1009          $courses = $DB->get_records('course', array('category'=>$cat->id), 'sortorder ASC, id DESC', 'id, sortorder');
1010          foreach ($courses as $course) {
1011              if ($course->sortorder != $cat->sortorder + $i) {
1012                  $course->sortorder = $cat->sortorder + $i;
1013                  $DB->update_record_raw('course', $course, true);
1014                  $cacheevents['changesincourse'] = true;
1015              }
1016              $i++;
1017          }
1018      }
1019  
1020      // advise all caches that need to be rebuilt
1021      foreach (array_keys($cacheevents) as $event) {
1022          cache_helper::purge_by_event($event);
1023      }
1024  }
1025  
1026  /**
1027   * Internal recursive category verification function, do not use directly!
1028   *
1029   * @todo Document the arguments of this function better
1030   *
1031   * @global object
1032   * @uses CONTEXT_COURSECAT
1033   * @param array $children
1034   * @param int $sortorder
1035   * @param string $parent
1036   * @param int $depth
1037   * @param string $path
1038   * @param array $fixcontexts
1039   * @return bool if changes were made
1040   */
1041  function _fix_course_cats($children, &$sortorder, $parent, $depth, $path, &$fixcontexts) {
1042      global $DB;
1043  
1044      $depth++;
1045      $changesmade = false;
1046  
1047      foreach ($children as $cat) {
1048          $sortorder = $sortorder + get_max_courses_in_category();
1049          $update = false;
1050          if ($parent != $cat->parent or $depth != $cat->depth or $path.'/'.$cat->id != $cat->path) {
1051              $cat->parent = $parent;
1052              $cat->depth  = $depth;
1053              $cat->path   = $path.'/'.$cat->id;
1054              $update = true;
1055  
1056              // make sure context caches are rebuild and dirty contexts marked
1057              $context = context_coursecat::instance($cat->id);
1058              $fixcontexts[$context->id] = $context;
1059          }
1060          if ($cat->sortorder != $sortorder) {
1061              $cat->sortorder = $sortorder;
1062              $update = true;
1063          }
1064          if ($update) {
1065              $DB->update_record('course_categories', $cat, true);
1066              $changesmade = true;
1067          }
1068          if (isset($cat->children)) {
1069              if (_fix_course_cats($cat->children, $sortorder, $cat->id, $cat->depth, $cat->path, $fixcontexts)) {
1070                  $changesmade = true;
1071              }
1072          }
1073      }
1074      return $changesmade;
1075  }
1076  
1077  /**
1078   * List of remote courses that a user has access to via MNET.
1079   * Works only on the IDP
1080   *
1081   * @global object
1082   * @global object
1083   * @param int @userid The user id to get remote courses for
1084   * @return array Array of {@link $COURSE} of course objects
1085   */
1086  function get_my_remotecourses($userid=0) {
1087      global $DB, $USER;
1088  
1089      if (empty($userid)) {
1090          $userid = $USER->id;
1091      }
1092  
1093      // we can not use SELECT DISTINCT + text field (summary) because of MS SQL and Oracle, subselect used therefore
1094      $sql = "SELECT c.id, c.remoteid, c.shortname, c.fullname,
1095                     c.hostid, c.summary, c.summaryformat, c.categoryname AS cat_name,
1096                     h.name AS hostname
1097                FROM {mnetservice_enrol_courses} c
1098                JOIN (SELECT DISTINCT hostid, remotecourseid
1099                        FROM {mnetservice_enrol_enrolments}
1100                       WHERE userid = ?
1101                     ) e ON (e.hostid = c.hostid AND e.remotecourseid = c.remoteid)
1102                JOIN {mnet_host} h ON h.id = c.hostid";
1103  
1104      return $DB->get_records_sql($sql, array($userid));
1105  }
1106  
1107  /**
1108   * List of remote hosts that a user has access to via MNET.
1109   * Works on the SP
1110   *
1111   * @global object
1112   * @global object
1113   * @return array|bool Array of host objects or false
1114   */
1115  function get_my_remotehosts() {
1116      global $CFG, $USER;
1117  
1118      if ($USER->mnethostid == $CFG->mnet_localhost_id) {
1119          return false; // Return nothing on the IDP
1120      }
1121      if (!empty($USER->mnet_foreign_host_array) && is_array($USER->mnet_foreign_host_array)) {
1122          return $USER->mnet_foreign_host_array;
1123      }
1124      return false;
1125  }
1126  
1127  
1128  /**
1129   * Returns a menu of all available scales from the site as well as the given course
1130   *
1131   * @global object
1132   * @param int $courseid The id of the course as found in the 'course' table.
1133   * @return array
1134   */
1135  function get_scales_menu($courseid=0) {
1136      global $DB;
1137  
1138      $sql = "SELECT id, name, courseid
1139                FROM {scale}
1140               WHERE courseid = 0 or courseid = ?
1141            ORDER BY courseid ASC, name ASC";
1142      $params = array($courseid);
1143      $scales = array();
1144      $results = $DB->get_records_sql($sql, $params);
1145      foreach ($results as $index => $record) {
1146          $context = empty($record->courseid) ? context_system::instance() : context_course::instance($record->courseid);
1147          $scales[$index] = format_string($record->name, false, ["context" => $context]);
1148      }
1149      // Format: [id => 'scale name'].
1150      return $scales;
1151  }
1152  
1153  /**
1154   * Increment standard revision field.
1155   *
1156   * The revision are based on current time and are incrementing.
1157   * There is a protection for runaway revisions, it may not go further than
1158   * one hour into future.
1159   *
1160   * The field has to be XMLDB_TYPE_INTEGER with size 10.
1161   *
1162   * @param string $table
1163   * @param string $field name of the field containing revision
1164   * @param string $select use empty string when updating all records
1165   * @param array $params optional select parameters
1166   */
1167  function increment_revision_number($table, $field, $select, array $params = null) {
1168      global $DB;
1169  
1170      $now = time();
1171      $sql = "UPDATE {{$table}}
1172                     SET $field = (CASE
1173                         WHEN $field IS NULL THEN $now
1174                         WHEN $field < $now THEN $now
1175                         WHEN $field > $now + 3600 THEN $now
1176                         ELSE $field + 1 END)";
1177      if ($select) {
1178          $sql = $sql . " WHERE $select";
1179      }
1180      $DB->execute($sql, $params);
1181  }
1182  
1183  
1184  /// MODULE FUNCTIONS /////////////////////////////////////////////////
1185  
1186  /**
1187   * Just gets a raw list of all modules in a course
1188   *
1189   * @global object
1190   * @param int $courseid The id of the course as found in the 'course' table.
1191   * @return array
1192   */
1193  function get_course_mods($courseid) {
1194      global $DB;
1195  
1196      if (empty($courseid)) {
1197          return false; // avoid warnings
1198      }
1199  
1200      return $DB->get_records_sql("SELECT cm.*, m.name as modname
1201                                     FROM {modules} m, {course_modules} cm
1202                                    WHERE cm.course = ? AND cm.module = m.id AND m.visible = 1",
1203                                  array($courseid)); // no disabled mods
1204  }
1205  
1206  
1207  /**
1208   * Given an id of a course module, finds the coursemodule description
1209   *
1210   * Please note that this function performs 1-2 DB queries. When possible use cached
1211   * course modinfo. For example get_fast_modinfo($courseorid)->get_cm($cmid)
1212   * See also {@link cm_info::get_course_module_record()}
1213   *
1214   * @global object
1215   * @param string $modulename name of module type, eg. resource, assignment,... (optional, slower and less safe if not specified)
1216   * @param int $cmid course module id (id in course_modules table)
1217   * @param int $courseid optional course id for extra validation
1218   * @param bool $sectionnum include relative section number (0,1,2 ...)
1219   * @param int $strictness IGNORE_MISSING means compatible mode, false returned if record not found, debug message if more found;
1220   *                        IGNORE_MULTIPLE means return first, ignore multiple records found(not recommended);
1221   *                        MUST_EXIST means throw exception if no record or multiple records found
1222   * @return stdClass
1223   */
1224  function get_coursemodule_from_id($modulename, $cmid, $courseid=0, $sectionnum=false, $strictness=IGNORE_MISSING) {
1225      global $DB;
1226  
1227      $params = array('cmid'=>$cmid);
1228  
1229      if (!$modulename) {
1230          if (!$modulename = $DB->get_field_sql("SELECT md.name
1231                                                   FROM {modules} md
1232                                                   JOIN {course_modules} cm ON cm.module = md.id
1233                                                  WHERE cm.id = :cmid", $params, $strictness)) {
1234              return false;
1235          }
1236      } else {
1237          if (!core_component::is_valid_plugin_name('mod', $modulename)) {
1238              throw new coding_exception('Invalid modulename parameter');
1239          }
1240      }
1241  
1242      $params['modulename'] = $modulename;
1243  
1244      $courseselect = "";
1245      $sectionfield = "";
1246      $sectionjoin  = "";
1247  
1248      if ($courseid) {
1249          $courseselect = "AND cm.course = :courseid";
1250          $params['courseid'] = $courseid;
1251      }
1252  
1253      if ($sectionnum) {
1254          $sectionfield = ", cw.section AS sectionnum";
1255          $sectionjoin  = "LEFT JOIN {course_sections} cw ON cw.id = cm.section";
1256      }
1257  
1258      $sql = "SELECT cm.*, m.name, md.name AS modname $sectionfield
1259                FROM {course_modules} cm
1260                     JOIN {modules} md ON md.id = cm.module
1261                     JOIN {".$modulename."} m ON m.id = cm.instance
1262                     $sectionjoin
1263               WHERE cm.id = :cmid AND md.name = :modulename
1264                     $courseselect";
1265  
1266      return $DB->get_record_sql($sql, $params, $strictness);
1267  }
1268  
1269  /**
1270   * Given an instance number of a module, finds the coursemodule description
1271   *
1272   * Please note that this function performs DB query. When possible use cached course
1273   * modinfo. For example get_fast_modinfo($courseorid)->instances[$modulename][$instance]
1274   * See also {@link cm_info::get_course_module_record()}
1275   *
1276   * @global object
1277   * @param string $modulename name of module type, eg. resource, assignment,...
1278   * @param int $instance module instance number (id in resource, assignment etc. table)
1279   * @param int $courseid optional course id for extra validation
1280   * @param bool $sectionnum include relative section number (0,1,2 ...)
1281   * @param int $strictness IGNORE_MISSING means compatible mode, false returned if record not found, debug message if more found;
1282   *                        IGNORE_MULTIPLE means return first, ignore multiple records found(not recommended);
1283   *                        MUST_EXIST means throw exception if no record or multiple records found
1284   * @return stdClass
1285   */
1286  function get_coursemodule_from_instance($modulename, $instance, $courseid=0, $sectionnum=false, $strictness=IGNORE_MISSING) {
1287      global $DB;
1288  
1289      if (!core_component::is_valid_plugin_name('mod', $modulename)) {
1290          throw new coding_exception('Invalid modulename parameter');
1291      }
1292  
1293      $params = array('instance'=>$instance, 'modulename'=>$modulename);
1294  
1295      $courseselect = "";
1296      $sectionfield = "";
1297      $sectionjoin  = "";
1298  
1299      if ($courseid) {
1300          $courseselect = "AND cm.course = :courseid";
1301          $params['courseid'] = $courseid;
1302      }
1303  
1304      if ($sectionnum) {
1305          $sectionfield = ", cw.section AS sectionnum";
1306          $sectionjoin  = "LEFT JOIN {course_sections} cw ON cw.id = cm.section";
1307      }
1308  
1309      $sql = "SELECT cm.*, m.name, md.name AS modname $sectionfield
1310                FROM {course_modules} cm
1311                     JOIN {modules} md ON md.id = cm.module
1312                     JOIN {".$modulename."} m ON m.id = cm.instance
1313                     $sectionjoin
1314               WHERE m.id = :instance AND md.name = :modulename
1315                     $courseselect";
1316  
1317      return $DB->get_record_sql($sql, $params, $strictness);
1318  }
1319  
1320  /**
1321   * Returns all course modules of given activity in course
1322   *
1323   * @param string $modulename The module name (forum, quiz, etc.)
1324   * @param int $courseid The course id to get modules for
1325   * @param string $extrafields extra fields starting with m.
1326   * @return array Array of results
1327   */
1328  function get_coursemodules_in_course($modulename, $courseid, $extrafields='') {
1329      global $DB;
1330  
1331      if (!core_component::is_valid_plugin_name('mod', $modulename)) {
1332          throw new coding_exception('Invalid modulename parameter');
1333      }
1334  
1335      if (!empty($extrafields)) {
1336          $extrafields = ", $extrafields";
1337      }
1338      $params = array();
1339      $params['courseid'] = $courseid;
1340      $params['modulename'] = $modulename;
1341  
1342  
1343      return $DB->get_records_sql("SELECT cm.*, m.name, md.name as modname $extrafields
1344                                     FROM {course_modules} cm, {modules} md, {".$modulename."} m
1345                                    WHERE cm.course = :courseid AND
1346                                          cm.instance = m.id AND
1347                                          md.name = :modulename AND
1348                                          md.id = cm.module", $params);
1349  }
1350  
1351  /**
1352   * Returns an array of all the active instances of a particular module in given courses, sorted in the order they are defined
1353   *
1354   * Returns an array of all the active instances of a particular
1355   * module in given courses, sorted in the order they are defined
1356   * in the course. Returns an empty array on any errors.
1357   *
1358   * The returned objects includle the columns cw.section, cm.visible,
1359   * cm.groupmode, and cm.groupingid, and are indexed by cm.id.
1360   *
1361   * @global object
1362   * @global object
1363   * @param string $modulename The name of the module to get instances for
1364   * @param array $courses an array of course objects.
1365   * @param int $userid
1366   * @param int $includeinvisible
1367   * @return array of module instance objects, including some extra fields from the course_modules
1368   *          and course_sections tables, or an empty array if an error occurred.
1369   */
1370  function get_all_instances_in_courses($modulename, $courses, $userid=NULL, $includeinvisible=false) {
1371      global $CFG, $DB;
1372  
1373      if (!core_component::is_valid_plugin_name('mod', $modulename)) {
1374          throw new coding_exception('Invalid modulename parameter');
1375      }
1376  
1377      $outputarray = array();
1378  
1379      if (empty($courses) || !is_array($courses) || count($courses) == 0) {
1380          return $outputarray;
1381      }
1382  
1383      list($coursessql, $params) = $DB->get_in_or_equal(array_keys($courses), SQL_PARAMS_NAMED, 'c0');
1384      $params['modulename'] = $modulename;
1385  
1386      if (!$rawmods = $DB->get_records_sql("SELECT cm.id AS coursemodule, m.*, cw.section, cm.visible AS visible,
1387                                                   cm.groupmode, cm.groupingid
1388                                              FROM {course_modules} cm, {course_sections} cw, {modules} md,
1389                                                   {".$modulename."} m
1390                                             WHERE cm.course $coursessql AND
1391                                                   cm.instance = m.id AND
1392                                                   cm.section = cw.id AND
1393                                                   md.name = :modulename AND
1394                                                   md.id = cm.module", $params)) {
1395          return $outputarray;
1396      }
1397  
1398      foreach ($courses as $course) {
1399          $modinfo = get_fast_modinfo($course, $userid);
1400  
1401          if (empty($modinfo->instances[$modulename])) {
1402              continue;
1403          }
1404  
1405          foreach ($modinfo->instances[$modulename] as $cm) {
1406              if (!$includeinvisible and !$cm->uservisible) {
1407                  continue;
1408              }
1409              if (!isset($rawmods[$cm->id])) {
1410                  continue;
1411              }
1412              $instance = $rawmods[$cm->id];
1413              if (!empty($cm->extra)) {
1414                  $instance->extra = $cm->extra;
1415              }
1416              $outputarray[] = $instance;
1417          }
1418      }
1419  
1420      return $outputarray;
1421  }
1422  
1423  /**
1424   * Returns an array of all the active instances of a particular module in a given course,
1425   * sorted in the order they are defined.
1426   *
1427   * Returns an array of all the active instances of a particular
1428   * module in a given course, sorted in the order they are defined
1429   * in the course. Returns an empty array on any errors.
1430   *
1431   * The returned objects includle the columns cw.section, cm.visible,
1432   * cm.groupmode, and cm.groupingid, and are indexed by cm.id.
1433   *
1434   * Simply calls {@link all_instances_in_courses()} with a single provided course
1435   *
1436   * @param string $modulename The name of the module to get instances for
1437   * @param object $course The course obect.
1438   * @return array of module instance objects, including some extra fields from the course_modules
1439   *          and course_sections tables, or an empty array if an error occurred.
1440   * @param int $userid
1441   * @param int $includeinvisible
1442   */
1443  function get_all_instances_in_course($modulename, $course, $userid=NULL, $includeinvisible=false) {
1444      return get_all_instances_in_courses($modulename, array($course->id => $course), $userid, $includeinvisible);
1445  }
1446  
1447  
1448  /**
1449   * Determine whether a module instance is visible within a course
1450   *
1451   * Given a valid module object with info about the id and course,
1452   * and the module's type (eg "forum") returns whether the object
1453   * is visible or not according to the 'eye' icon only.
1454   *
1455   * NOTE: This does NOT take into account visibility to a particular user.
1456   * To get visibility access for a specific user, use get_fast_modinfo, get a
1457   * cm_info object from this, and check the ->uservisible property; or use
1458   * the \core_availability\info_module::is_user_visible() static function.
1459   *
1460   * @global object
1461  
1462   * @param $moduletype Name of the module eg 'forum'
1463   * @param $module Object which is the instance of the module
1464   * @return bool Success
1465   */
1466  function instance_is_visible($moduletype, $module) {
1467      global $DB;
1468  
1469      if (!empty($module->id)) {
1470          $params = array('courseid'=>$module->course, 'moduletype'=>$moduletype, 'moduleid'=>$module->id);
1471          if ($records = $DB->get_records_sql("SELECT cm.instance, cm.visible, cm.groupingid, cm.id, cm.course
1472                                                 FROM {course_modules} cm, {modules} m
1473                                                WHERE cm.course = :courseid AND
1474                                                      cm.module = m.id AND
1475                                                      m.name = :moduletype AND
1476                                                      cm.instance = :moduleid", $params)) {
1477  
1478              foreach ($records as $record) { // there should only be one - use the first one
1479                  return $record->visible;
1480              }
1481          }
1482      }
1483      return true;  // visible by default!
1484  }
1485  
1486  
1487  /// LOG FUNCTIONS /////////////////////////////////////////////////////
1488  
1489  /**
1490   * Get instance of log manager.
1491   *
1492   * @param bool $forcereload
1493   * @return \core\log\manager
1494   */
1495  function get_log_manager($forcereload = false) {
1496      /** @var \core\log\manager $singleton */
1497      static $singleton = null;
1498  
1499      if ($forcereload and isset($singleton)) {
1500          $singleton->dispose();
1501          $singleton = null;
1502      }
1503  
1504      if (isset($singleton)) {
1505          return $singleton;
1506      }
1507  
1508      $classname = '\tool_log\log\manager';
1509      if (defined('LOG_MANAGER_CLASS')) {
1510          $classname = LOG_MANAGER_CLASS;
1511      }
1512  
1513      if (!class_exists($classname)) {
1514          if (!empty($classname)) {
1515              debugging("Cannot find log manager class '$classname'.", DEBUG_DEVELOPER);
1516          }
1517          $classname = '\core\log\dummy_manager';
1518      }
1519  
1520      $singleton = new $classname();
1521      return $singleton;
1522  }
1523  
1524  /**
1525   * Add an entry to the config log table.
1526   *
1527   * These are "action" focussed rather than web server hits,
1528   * and provide a way to easily reconstruct changes to Moodle configuration.
1529   *
1530   * @package core
1531   * @category log
1532   * @global moodle_database $DB
1533   * @global stdClass $USER
1534   * @param    string  $name     The name of the configuration change action
1535                                 For example 'filter_active' when activating or deactivating a filter
1536   * @param    string  $oldvalue The config setting's previous value
1537   * @param    string  $value    The config setting's new value
1538   * @param    string  $plugin   Plugin name, for example a filter name when changing filter configuration
1539   * @return void
1540   */
1541  function add_to_config_log($name, $oldvalue, $value, $plugin) {
1542      global $USER, $DB;
1543  
1544      $log = new stdClass();
1545      // Use 0 as user id during install.
1546      $log->userid       = during_initial_install() ? 0 : $USER->id;
1547      $log->timemodified = time();
1548      $log->name         = $name;
1549      $log->oldvalue  = $oldvalue;
1550      $log->value     = $value;
1551      $log->plugin    = $plugin;
1552  
1553      $id = $DB->insert_record('config_log', $log);
1554  
1555      $event = core\event\config_log_created::create(array(
1556              'objectid' => $id,
1557              'userid' => $log->userid,
1558              'context' => \context_system::instance(),
1559              'other' => array(
1560                  'name' => $log->name,
1561                  'oldvalue' => $log->oldvalue,
1562                  'value' => $log->value,
1563                  'plugin' => $log->plugin
1564              )
1565          ));
1566      $event->trigger();
1567  }
1568  
1569  /**
1570   * Store user last access times - called when use enters a course or site
1571   *
1572   * @package core
1573   * @category log
1574   * @global stdClass $USER
1575   * @global stdClass $CFG
1576   * @global moodle_database $DB
1577   * @uses LASTACCESS_UPDATE_SECS
1578   * @uses SITEID
1579   * @param int $courseid  empty courseid means site
1580   * @return void
1581   */
1582  function user_accesstime_log($courseid=0) {
1583      global $USER, $CFG, $DB;
1584  
1585      if (!isloggedin() or \core\session\manager::is_loggedinas()) {
1586          // no access tracking
1587          return;
1588      }
1589  
1590      if (isguestuser()) {
1591          // Do not update guest access times/ips for performance.
1592          return;
1593      }
1594  
1595      if (defined('USER_KEY_LOGIN') && USER_KEY_LOGIN === true) {
1596          // Do not update user login time when using user key login.
1597          return;
1598      }
1599  
1600      if (empty($courseid)) {
1601          $courseid = SITEID;
1602      }
1603  
1604      $timenow = time();
1605  
1606  /// Store site lastaccess time for the current user
1607      if ($timenow - $USER->lastaccess > LASTACCESS_UPDATE_SECS) {
1608      /// Update $USER->lastaccess for next checks
1609          $USER->lastaccess = $timenow;
1610  
1611          $last = new stdClass();
1612          $last->id         = $USER->id;
1613          $last->lastip     = getremoteaddr();
1614          $last->lastaccess = $timenow;
1615  
1616          $DB->update_record_raw('user', $last);
1617      }
1618  
1619      if ($courseid == SITEID) {
1620      ///  no user_lastaccess for frontpage
1621          return;
1622      }
1623  
1624  /// Store course lastaccess times for the current user
1625      if (empty($USER->currentcourseaccess[$courseid]) or ($timenow - $USER->currentcourseaccess[$courseid] > LASTACCESS_UPDATE_SECS)) {
1626  
1627          $lastaccess = $DB->get_field('user_lastaccess', 'timeaccess', array('userid'=>$USER->id, 'courseid'=>$courseid));
1628  
1629          if ($lastaccess === false) {
1630              // Update course lastaccess for next checks
1631              $USER->currentcourseaccess[$courseid] = $timenow;
1632  
1633              $last = new stdClass();
1634              $last->userid     = $USER->id;
1635              $last->courseid   = $courseid;
1636              $last->timeaccess = $timenow;
1637              try {
1638                  $DB->insert_record_raw('user_lastaccess', $last, false);
1639              } catch (dml_write_exception $e) {
1640                  // During a race condition we can fail to find the data, then it appears.
1641                  // If we still can't find it, rethrow the exception.
1642                  $lastaccess = $DB->get_field('user_lastaccess', 'timeaccess', array('userid' => $USER->id,
1643                                                                                      'courseid' => $courseid));
1644                  if ($lastaccess === false) {
1645                      throw $e;
1646                  }
1647                  // If we did find it, the race condition was true and another thread has inserted the time for us.
1648                  // We can just continue without having to do anything.
1649              }
1650  
1651          } else if ($timenow - $lastaccess <  LASTACCESS_UPDATE_SECS) {
1652              // no need to update now, it was updated recently in concurrent login ;-)
1653  
1654          } else {
1655              // Update course lastaccess for next checks
1656              $USER->currentcourseaccess[$courseid] = $timenow;
1657  
1658              $DB->set_field('user_lastaccess', 'timeaccess', $timenow, array('userid'=>$USER->id, 'courseid'=>$courseid));
1659          }
1660      }
1661  }
1662  
1663  /// GENERAL HELPFUL THINGS  ///////////////////////////////////
1664  
1665  /**
1666   * Dumps a given object's information for debugging purposes
1667   *
1668   * When used in a CLI script, the object's information is written to the standard
1669   * error output stream. When used in a web script, the object is dumped to a
1670   * pre-formatted block with the "notifytiny" CSS class.
1671   *
1672   * @param mixed $object The data to be printed
1673   * @return void output is echo'd
1674   */
1675  function print_object($object) {
1676  
1677      // we may need a lot of memory here
1678      raise_memory_limit(MEMORY_EXTRA);
1679  
1680      if (CLI_SCRIPT) {
1681          fwrite(STDERR, print_r($object, true));
1682          fwrite(STDERR, PHP_EOL);
1683      } else if (AJAX_SCRIPT) {
1684          foreach (explode("\n", print_r($object, true)) as $line) {
1685              error_log($line);
1686          }
1687      } else {
1688          echo html_writer::tag('pre', s(print_r($object, true)), array('class' => 'notifytiny'));
1689      }
1690  }
1691  
1692  /**
1693   * This function is the official hook inside XMLDB stuff to delegate its debug to one
1694   * external function.
1695   *
1696   * Any script can avoid calls to this function by defining XMLDB_SKIP_DEBUG_HOOK before
1697   * using XMLDB classes. Obviously, also, if this function doesn't exist, it isn't invoked ;-)
1698   *
1699   * @uses DEBUG_DEVELOPER
1700   * @param string $message string contains the error message
1701   * @param object $object object XMLDB object that fired the debug
1702   */
1703  function xmldb_debug($message, $object) {
1704  
1705      debugging($message, DEBUG_DEVELOPER);
1706  }
1707  
1708  /**
1709   * @global object
1710   * @uses CONTEXT_COURSECAT
1711   * @return boolean Whether the user can create courses in any category in the system.
1712   */
1713  function user_can_create_courses() {
1714      global $DB;
1715      $catsrs = $DB->get_recordset('course_categories');
1716      foreach ($catsrs as $cat) {
1717          if (has_capability('moodle/course:create', context_coursecat::instance($cat->id))) {
1718              $catsrs->close();
1719              return true;
1720          }
1721      }
1722      $catsrs->close();
1723      return false;
1724  }
1725  
1726  /**
1727   * This method can update the values in mulitple database rows for a colum with
1728   * a unique index, without violating that constraint.
1729   *
1730   * Suppose we have a table with a unique index on (otherid, sortorder), and
1731   * for a particular value of otherid, we want to change all the sort orders.
1732   * You have to do this carefully or you will violate the unique index at some time.
1733   * This method takes care of the details for you.
1734   *
1735   * Note that, it is the responsibility of the caller to make sure that the
1736   * requested rename is legal. For example, if you ask for [1 => 2, 2 => 2]
1737   * then you will get a unique key violation error from the database.
1738   *
1739   * @param string $table The database table to modify.
1740   * @param string $field the field that contains the values we are going to change.
1741   * @param array $newvalues oldvalue => newvalue how to change the values.
1742   *      E.g. [1 => 4, 2 => 1, 3 => 3, 4 => 2].
1743   * @param array $otherconditions array fieldname => requestedvalue extra WHERE clause
1744   *      conditions to restrict which rows are affected. E.g. array('otherid' => 123).
1745   * @param int $unusedvalue (defaults to -1) a value that is never used in $ordercol.
1746   */
1747  function update_field_with_unique_index($table, $field, array $newvalues,
1748          array $otherconditions, $unusedvalue = -1) {
1749      global $DB;
1750      $safechanges = decompose_update_into_safe_changes($newvalues, $unusedvalue);
1751  
1752      $transaction = $DB->start_delegated_transaction();
1753      foreach ($safechanges as $change) {
1754          list($from, $to) = $change;
1755          $otherconditions[$field] = $from;
1756          $DB->set_field($table, $field, $to, $otherconditions);
1757      }
1758      $transaction->allow_commit();
1759  }
1760  
1761  /**
1762   * Helper used by {@link update_field_with_unique_index()}. Given a desired
1763   * set of changes, break them down into single udpates that can be done one at
1764   * a time without breaking any unique index constraints.
1765   *
1766   * Suppose the input is array(1 => 2, 2 => 1) and -1. Then the output will be
1767   * array (array(1, -1), array(2, 1), array(-1, 2)). This function solves this
1768   * problem in the general case, not just for simple swaps. The unit tests give
1769   * more examples.
1770   *
1771   * Note that, it is the responsibility of the caller to make sure that the
1772   * requested rename is legal. For example, if you ask for something impossible
1773   * like array(1 => 2, 2 => 2) then the results are undefined. (You will probably
1774   * get a unique key violation error from the database later.)
1775   *
1776   * @param array $newvalues The desired re-ordering.
1777   *      E.g. array(1 => 4, 2 => 1, 3 => 3, 4 => 2).
1778   * @param int $unusedvalue A value that is not currently used.
1779   * @return array A safe way to perform the re-order. An array of two-element
1780   *      arrays array($from, $to).
1781   *      E.g. array(array(1, -1), array(2, 1), array(4, 2), array(-1, 4)).
1782   */
1783  function decompose_update_into_safe_changes(array $newvalues, $unusedvalue) {
1784      $nontrivialmap = array();
1785      foreach ($newvalues as $from => $to) {
1786          if ($from == $unusedvalue || $to == $unusedvalue) {
1787              throw new \coding_exception('Supposedly unused value ' . $unusedvalue . ' is actually used!');
1788          }
1789          if ($from != $to) {
1790              $nontrivialmap[$from] = $to;
1791          }
1792      }
1793  
1794      if (empty($nontrivialmap)) {
1795          return array();
1796      }
1797  
1798      // First we deal with all renames that are not part of cycles.
1799      // This bit is O(n^2) and it ought to be possible to do better,
1800      // but it does not seem worth the effort.
1801      $safechanges = array();
1802      $nontrivialmapchanged = true;
1803      while ($nontrivialmapchanged) {
1804          $nontrivialmapchanged = false;
1805  
1806          foreach ($nontrivialmap as $from => $to) {
1807              if (array_key_exists($to, $nontrivialmap)) {
1808                  continue; // Cannot currenly do this rename.
1809              }
1810              // Is safe to do this rename now.
1811              $safechanges[] = array($from, $to);
1812              unset($nontrivialmap[$from]);
1813              $nontrivialmapchanged = true;
1814          }
1815      }
1816  
1817      // Are we done?
1818      if (empty($nontrivialmap)) {
1819          return $safechanges;
1820      }
1821  
1822      // Now what is left in $nontrivialmap must be a permutation,
1823      // which must be a combination of disjoint cycles. We need to break them.
1824      while (!empty($nontrivialmap)) {
1825          // Extract the first cycle.
1826          reset($nontrivialmap);
1827          $current = $cyclestart = key($nontrivialmap);
1828          $cycle = array();
1829          do {
1830              $cycle[] = $current;
1831              $next = $nontrivialmap[$current];
1832              unset($nontrivialmap[$current]);
1833              $current = $next;
1834          } while ($current != $cyclestart);
1835  
1836          // Now convert it to a sequence of safe renames by using a temp.
1837          $safechanges[] = array($cyclestart, $unusedvalue);
1838          $cycle[0] = $unusedvalue;
1839          $to = $cyclestart;
1840          while ($from = array_pop($cycle)) {
1841              $safechanges[] = array($from, $to);
1842              $to = $from;
1843          }
1844      }
1845  
1846      return $safechanges;
1847  }
1848  
1849  /**
1850   * Return maximum number of courses in a category
1851   *
1852   * @uses MAX_COURSES_IN_CATEGORY
1853   * @return int number of courses
1854   */
1855  function get_max_courses_in_category() {
1856      global $CFG;
1857      // Use default MAX_COURSES_IN_CATEGORY if $CFG->maxcoursesincategory is not set or invalid.
1858      if (!isset($CFG->maxcoursesincategory) || clean_param($CFG->maxcoursesincategory, PARAM_INT) == 0) {
1859          return MAX_COURSES_IN_CATEGORY;
1860      } else {
1861          return $CFG->maxcoursesincategory;
1862      }
1863  }
1864  
1865  /**
1866   * Prepare a safe ORDER BY statement from user interactable requests.
1867   *
1868   * This allows safe user specified sorting (ORDER BY), by abstracting the SQL from the value being requested by the user.
1869   * A standard string (and optional direction) can be specified, which will be mapped to a predefined allow list of SQL ordering.
1870   * The mapping can optionally include a 'default', which will be used if the key provided is invalid.
1871   *
1872   * Example usage:
1873   *      -If $orderbymap = [
1874   *              'courseid' => 'c.id',
1875   *              'somecustomvalue'=> 'c.startdate, c.shortname',
1876   *              'default' => 'c.fullname',
1877   *       ]
1878   *      -A value from the map array's keys can be passed in by a user interaction (eg web service) along with an optional direction.
1879   *      -get_safe_orderby($orderbymap, 'courseid', 'DESC') would return: ORDER BY c.id DESC
1880   *      -get_safe_orderby($orderbymap, 'somecustomvalue') would return: ORDER BY c.startdate, c.shortname
1881   *      -get_safe_orderby($orderbymap, 'invalidblah', 'DESC') would return: ORDER BY c.fullname DESC
1882   *      -If no default key was specified in $orderbymap, the invalidblah example above would return empty string.
1883   *
1884   * @param array $orderbymap An array in the format [keystring => sqlstring]. A default fallback can be set with the key 'default'.
1885   * @param string $orderbykey A string to be mapped to a key in $orderbymap.
1886   * @param string $direction Optional ORDER BY direction (ASC/DESC, case insensitive).
1887   * @param bool $useprefix Whether ORDER BY is prefixed to the output (true by default). This should not be modified in most cases.
1888   *                        It is included to enable get_safe_orderby_multiple() to use this function multiple times.
1889   * @return string The ORDER BY statement, or empty string if $orderbykey is invalid and no default is mapped.
1890   */
1891  function get_safe_orderby(array $orderbymap, string $orderbykey, string $direction = '', bool $useprefix = true): string {
1892      $orderby = $useprefix ? ' ORDER BY ' : '';
1893      $output = '';
1894  
1895      // Only include an order direction if ASC/DESC is explicitly specified (case insensitive).
1896      $direction = strtoupper($direction);
1897      if (!in_array($direction, ['ASC', 'DESC'], true)) {
1898          $direction = '';
1899      } else {
1900          $direction = " {$direction}";
1901      }
1902  
1903      // Prepare the statement if the key maps to a defined sort parameter.
1904      if (isset($orderbymap[$orderbykey])) {
1905          $output = "{$orderby}{$orderbymap[$orderbykey]}{$direction}";
1906      } else if (array_key_exists('default', $orderbymap)) {
1907          // Fall back to use the default if one is specified.
1908          $output = "{$orderby}{$orderbymap['default']}{$direction}";
1909      }
1910  
1911      return $output;
1912  }
1913  
1914  /**
1915   * Prepare a safe ORDER BY statement from user interactable requests using multiple values.
1916   *
1917   * This allows safe user specified sorting (ORDER BY) similar to get_safe_orderby(), but supports multiple keys and directions.
1918   * This is useful in cases where combinations of columns are needed and/or each item requires a specified direction (ASC/DESC).
1919   * The mapping can optionally include a 'default', which will be used if the key provided is invalid.
1920   *
1921   * Example usage:
1922   *      -If $orderbymap = [
1923   *              'courseid' => 'c.id',
1924   *              'fullname'=> 'c.fullname',
1925   *              'default' => 'c.startdate',
1926   *          ]
1927   *      -An array of values from the map's keys can be passed in by a user interaction (eg web service), with optional directions.
1928   *      -get_safe_orderby($orderbymap, ['courseid', 'fullname'], ['DESC', 'ASC']) would return: ORDER BY c.id DESC, c.fullname ASC
1929   *      -get_safe_orderby($orderbymap, ['courseid', 'invalidblah'], ['aaa', 'DESC']) would return: ORDER BY c.id, c.startdate DESC
1930   *      -If no default key was specified in $orderbymap, the invalidblah example above would return: ORDER BY c.id
1931   *
1932   * @param array $orderbymap An array in the format [keystring => sqlstring]. A default fallback can be set with the key 'default'.
1933   * @param array $orderbykeys An array of strings to be mapped to keys in $orderbymap.
1934   * @param array $directions Optional array of ORDER BY direction (ASC/DESC, case insensitive).
1935   *                          The array keys should match array keys in $orderbykeys.
1936   * @return string The ORDER BY statement, or empty string if $orderbykeys contains no valid items and no default is mapped.
1937   */
1938  function get_safe_orderby_multiple(array $orderbymap, array $orderbykeys, array $directions = []): string {
1939      $output = '';
1940  
1941      // Check each key for a valid mapping and add to the ORDER BY statement (invalid entries will be empty strings).
1942      foreach ($orderbykeys as $index => $orderbykey) {
1943          $direction = $directions[$index] ?? '';
1944          $safeorderby = get_safe_orderby($orderbymap, $orderbykey, $direction, false);
1945  
1946          if (!empty($safeorderby)) {
1947              $output .= ", {$safeorderby}";
1948          }
1949      }
1950  
1951      // Prefix with ORDER BY if any valid ordering is specified (and remove comma from the start).
1952      if (!empty($output)) {
1953          $output = ' ORDER BY' . ltrim($output, ',');
1954      }
1955  
1956      return $output;
1957  }