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Differences Between: [Versions 311 and 400] [Versions 311 and 401] [Versions 311 and 402] [Versions 311 and 403]

   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   * More object oriented wrappers around parts of the Moodle question bank.
  19   *
  20   * In due course, I expect that the question bank will be converted to a
  21   * fully object oriented structure, at which point this file can be a
  22   * starting point.
  23   *
  24   * @package    moodlecore
  25   * @subpackage questionbank
  26   * @copyright  2009 The Open University
  27   * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
  28   */
  29  
  30  
  31  defined('MOODLE_INTERNAL') || die();
  32  
  33  require_once (__DIR__ . '/../type/questiontypebase.php');
  34  
  35  
  36  /**
  37   * This static class provides access to the other question bank.
  38   *
  39   * It provides functions for managing question types and question definitions.
  40   *
  41   * @copyright  2009 The Open University
  42   * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
  43   */
  44  abstract class question_bank {
  45      // TODO: This limit can be deleted if someday we move all TEXTS to BIG ones. MDL-19603
  46      const MAX_SUMMARY_LENGTH = 32000;
  47  
  48      /** @var array question type name => question_type subclass. */
  49      private static $questiontypes = array();
  50  
  51      /** @var array question type name => 1. Records which question definitions have been loaded. */
  52      private static $loadedqdefs = array();
  53  
  54      /** @var boolean nasty hack to allow unit tests to call {@link load_question()}. */
  55      private static $testmode = false;
  56      private static $testdata = array();
  57  
  58      private static $questionconfig = null;
  59  
  60      /**
  61       * @var array string => string The standard set of grade options (fractions)
  62       * to use when editing questions, in the range 0 to 1 inclusive. Array keys
  63       * are string becuase: a) we want grades to exactly 7 d.p., and b. you can't
  64       * have float array keys in PHP.
  65       * Initialised by {@link ensure_grade_options_initialised()}.
  66       */
  67      private static $fractionoptions = null;
  68      /** @var array string => string The full standard set of (fractions) -1 to 1 inclusive. */
  69      private static $fractionoptionsfull = null;
  70  
  71      /**
  72       * @param string $qtypename a question type name, e.g. 'multichoice'.
  73       * @return bool whether that question type is installed in this Moodle.
  74       */
  75      public static function is_qtype_installed($qtypename) {
  76          $plugindir = core_component::get_plugin_directory('qtype', $qtypename);
  77          return $plugindir && is_readable($plugindir . '/questiontype.php');
  78      }
  79  
  80      /**
  81       * Get the question type class for a particular question type.
  82       * @param string $qtypename the question type name. For example 'multichoice' or 'shortanswer'.
  83       * @param bool $mustexist if false, the missing question type is returned when
  84       *      the requested question type is not installed.
  85       * @return question_type the corresponding question type class.
  86       */
  87      public static function get_qtype($qtypename, $mustexist = true) {
  88          global $CFG;
  89          if (isset(self::$questiontypes[$qtypename])) {
  90              return self::$questiontypes[$qtypename];
  91          }
  92          $file = core_component::get_plugin_directory('qtype', $qtypename) . '/questiontype.php';
  93          if (!is_readable($file)) {
  94              if ($mustexist || $qtypename == 'missingtype') {
  95                  throw new coding_exception('Unknown question type ' . $qtypename);
  96              } else {
  97                  return self::get_qtype('missingtype');
  98              }
  99          }
 100          include_once($file);
 101          $class = 'qtype_' . $qtypename;
 102          if (!class_exists($class)) {
 103              throw new coding_exception("Class {$class} must be defined in {$file}.");
 104          }
 105          self::$questiontypes[$qtypename] = new $class();
 106          return self::$questiontypes[$qtypename];
 107      }
 108  
 109      /**
 110       * Load the question configuration data from config_plugins.
 111       * @return object get_config('question') with caching.
 112       */
 113      public static function get_config() {
 114          if (is_null(self::$questionconfig)) {
 115              self::$questionconfig = get_config('question');
 116          }
 117          return self::$questionconfig;
 118      }
 119  
 120      /**
 121       * @param string $qtypename the internal name of a question type. For example multichoice.
 122       * @return bool whether users are allowed to create questions of this type.
 123       */
 124      public static function qtype_enabled($qtypename) {
 125          $config = self::get_config();
 126          $enabledvar = $qtypename . '_disabled';
 127          return self::qtype_exists($qtypename) && empty($config->$enabledvar) &&
 128                  self::get_qtype($qtypename)->menu_name() != '';
 129      }
 130  
 131      /**
 132       * @param string $qtypename the internal name of a question type. For example multichoice.
 133       * @return bool whether this question type exists.
 134       */
 135      public static function qtype_exists($qtypename) {
 136          return array_key_exists($qtypename, core_component::get_plugin_list('qtype'));
 137      }
 138  
 139      /**
 140       * @param $qtypename the internal name of a question type, for example multichoice.
 141       * @return string the human_readable name of this question type, from the language pack.
 142       */
 143      public static function get_qtype_name($qtypename) {
 144          return self::get_qtype($qtypename)->local_name();
 145      }
 146  
 147      /**
 148       * @return array all the installed question types.
 149       */
 150      public static function get_all_qtypes() {
 151          $qtypes = array();
 152          foreach (core_component::get_plugin_list('qtype') as $plugin => $notused) {
 153              try {
 154                  $qtypes[$plugin] = self::get_qtype($plugin);
 155              } catch (coding_exception $e) {
 156                  // Catching coding_exceptions here means that incompatible
 157                  // question types do not cause the rest of Moodle to break.
 158              }
 159          }
 160          return $qtypes;
 161      }
 162  
 163      /**
 164       * Sort an array of question types according to the order the admin set up,
 165       * and then alphabetically for the rest.
 166       * @param array qtype->name() => qtype->local_name().
 167       * @return array sorted array.
 168       */
 169      public static function sort_qtype_array($qtypes, $config = null) {
 170          if (is_null($config)) {
 171              $config = self::get_config();
 172          }
 173  
 174          $sortorder = array();
 175          $otherqtypes = array();
 176          foreach ($qtypes as $name => $localname) {
 177              $sortvar = $name . '_sortorder';
 178              if (isset($config->$sortvar)) {
 179                  $sortorder[$config->$sortvar] = $name;
 180              } else {
 181                  $otherqtypes[$name] = $localname;
 182              }
 183          }
 184  
 185          ksort($sortorder);
 186          core_collator::asort($otherqtypes);
 187  
 188          $sortedqtypes = array();
 189          foreach ($sortorder as $name) {
 190              $sortedqtypes[$name] = $qtypes[$name];
 191          }
 192          foreach ($otherqtypes as $name => $notused) {
 193              $sortedqtypes[$name] = $qtypes[$name];
 194          }
 195          return $sortedqtypes;
 196      }
 197  
 198      /**
 199       * @return array all the question types that users are allowed to create,
 200       *      sorted into the preferred order set on the admin screen.
 201       */
 202      public static function get_creatable_qtypes() {
 203          $config = self::get_config();
 204          $allqtypes = self::get_all_qtypes();
 205  
 206          $qtypenames = array();
 207          foreach ($allqtypes as $name => $qtype) {
 208              if (self::qtype_enabled($name)) {
 209                  $qtypenames[$name] = $qtype->local_name();
 210              }
 211          }
 212  
 213          $qtypenames = self::sort_qtype_array($qtypenames);
 214  
 215          $creatableqtypes = array();
 216          foreach ($qtypenames as $name => $notused) {
 217              $creatableqtypes[$name] = $allqtypes[$name];
 218          }
 219          return $creatableqtypes;
 220      }
 221  
 222      /**
 223       * Load the question definition class(es) belonging to a question type. That is,
 224       * include_once('/question/type/' . $qtypename . '/question.php'), with a bit
 225       * of checking.
 226       * @param string $qtypename the question type name. For example 'multichoice' or 'shortanswer'.
 227       */
 228      public static function load_question_definition_classes($qtypename) {
 229          global $CFG;
 230          if (isset(self::$loadedqdefs[$qtypename])) {
 231              return;
 232          }
 233          $file = $CFG->dirroot . '/question/type/' . $qtypename . '/question.php';
 234          if (!is_readable($file)) {
 235              throw new coding_exception('Unknown question type (no definition) ' . $qtypename);
 236          }
 237          include_once($file);
 238          self::$loadedqdefs[$qtypename] = 1;
 239      }
 240  
 241      /**
 242       * This method needs to be called whenever a question is edited.
 243       */
 244      public static function notify_question_edited($questionid) {
 245          question_finder::get_instance()->uncache_question($questionid);
 246      }
 247  
 248      /**
 249       * Load a question definition data from the database. The data will be
 250       * returned as a plain stdClass object.
 251       * @param int $questionid the id of the question to load.
 252       * @return object question definition loaded from the database.
 253       */
 254      public static function load_question_data($questionid) {
 255          return question_finder::get_instance()->load_question_data($questionid);
 256      }
 257  
 258      /**
 259       * Load a question definition from the database. The object returned
 260       * will actually be of an appropriate {@link question_definition} subclass.
 261       * @param int $questionid the id of the question to load.
 262       * @param bool $allowshuffle if false, then any shuffle option on the selected
 263       *      quetsion is disabled.
 264       * @return question_definition loaded from the database.
 265       */
 266      public static function load_question($questionid, $allowshuffle = true) {
 267  
 268          if (self::$testmode) {
 269              // Evil, test code in production, but no way round it.
 270              return self::return_test_question_data($questionid);
 271          }
 272  
 273          $questiondata = self::load_question_data($questionid);
 274  
 275          if (!$allowshuffle) {
 276              $questiondata->options->shuffleanswers = false;
 277          }
 278          return self::make_question($questiondata);
 279      }
 280  
 281      /**
 282       * Convert the question information loaded with {@link get_question_options()}
 283       * to a question_definintion object.
 284       * @param object $questiondata raw data loaded from the database.
 285       * @return question_definition loaded from the database.
 286       */
 287      public static function make_question($questiondata) {
 288          return self::get_qtype($questiondata->qtype, false)->make_question($questiondata, false);
 289      }
 290  
 291      /**
 292       * @return question_finder a question finder.
 293       */
 294      public static function get_finder() {
 295          return question_finder::get_instance();
 296      }
 297  
 298      /**
 299       * Only to be called from unit tests. Allows {@link load_test_data()} to be used.
 300       */
 301      public static function start_unit_test() {
 302          self::$testmode = true;
 303      }
 304  
 305      /**
 306       * Only to be called from unit tests. Allows {@link load_test_data()} to be used.
 307       */
 308      public static function end_unit_test() {
 309          self::$testmode = false;
 310          self::$testdata = array();
 311      }
 312  
 313      private static function return_test_question_data($questionid) {
 314          if (!isset(self::$testdata[$questionid])) {
 315              throw new coding_exception('question_bank::return_test_data(' . $questionid .
 316                      ') called, but no matching question has been loaded by load_test_data.');
 317          }
 318          return self::$testdata[$questionid];
 319      }
 320  
 321      /**
 322       * To be used for unit testing only. Will throw an exception if
 323       * {@link start_unit_test()} has not been called first.
 324       * @param object $questiondata a question data object to put in the test data store.
 325       */
 326      public static function load_test_question_data(question_definition $question) {
 327          if (!self::$testmode) {
 328              throw new coding_exception('question_bank::load_test_data called when ' .
 329                      'not in test mode.');
 330          }
 331          self::$testdata[$question->id] = $question;
 332      }
 333  
 334      protected static function ensure_fraction_options_initialised() {
 335          if (!is_null(self::$fractionoptions)) {
 336              return;
 337          }
 338  
 339          // define basic array of grades. This list comprises all fractions of the form:
 340          // a. p/q for q <= 6, 0 <= p <= q
 341          // b. p/10 for 0 <= p <= 10
 342          // c. 1/q for 1 <= q <= 10
 343          // d. 1/20
 344          $rawfractions = array(
 345              0.9000000,
 346              0.8333333,
 347              0.8000000,
 348              0.7500000,
 349              0.7000000,
 350              0.6666667,
 351              0.6000000,
 352              0.5000000,
 353              0.4000000,
 354              0.3333333,
 355              0.3000000,
 356              0.2500000,
 357              0.2000000,
 358              0.1666667,
 359              0.1428571,
 360              0.1250000,
 361              0.1111111,
 362              0.1000000,
 363              0.0500000,
 364          );
 365  
 366          // Put the None option at the top.
 367          self::$fractionoptions = array(
 368              '0.0' => get_string('none'),
 369              '1.0' => '100%',
 370          );
 371          self::$fractionoptionsfull = array(
 372              '0.0' => get_string('none'),
 373              '1.0' => '100%',
 374          );
 375  
 376          // The the positive grades in descending order.
 377          foreach ($rawfractions as $fraction) {
 378              $percentage = format_float(100 * $fraction, 5, true, true) . '%';
 379              self::$fractionoptions["{$fraction}"] = $percentage;
 380              self::$fractionoptionsfull["{$fraction}"] = $percentage;
 381          }
 382  
 383          // The the negative grades in descending order.
 384          foreach (array_reverse($rawfractions) as $fraction) {
 385              self::$fractionoptionsfull['' . (-$fraction)] =
 386                      format_float(-100 * $fraction, 5, true, true) . '%';
 387          }
 388  
 389          self::$fractionoptionsfull['-1.0'] = '-100%';
 390      }
 391  
 392      /**
 393       * @return array string => string The standard set of grade options (fractions)
 394       * to use when editing questions, in the range 0 to 1 inclusive. Array keys
 395       * are string becuase: a) we want grades to exactly 7 d.p., and b. you can't
 396       * have float array keys in PHP.
 397       * Initialised by {@link ensure_grade_options_initialised()}.
 398       */
 399      public static function fraction_options() {
 400          self::ensure_fraction_options_initialised();
 401          return self::$fractionoptions;
 402      }
 403  
 404      /** @return array string => string The full standard set of (fractions) -1 to 1 inclusive. */
 405      public static function fraction_options_full() {
 406          self::ensure_fraction_options_initialised();
 407          return self::$fractionoptionsfull;
 408      }
 409  
 410      /**
 411       * Return a list of the different question types present in the given categories.
 412       *
 413       * @param  array $categories a list of category ids
 414       * @return array the list of question types in the categories
 415       * @since  Moodle 3.1
 416       */
 417      public static function get_all_question_types_in_categories($categories) {
 418          global $DB;
 419  
 420          list($categorysql, $params) = $DB->get_in_or_equal($categories);
 421          $sql = "SELECT DISTINCT q.qtype
 422                  FROM {question} q
 423                  WHERE q.category $categorysql";
 424  
 425          $qtypes = $DB->get_fieldset_sql($sql, $params);
 426          return $qtypes;
 427      }
 428  }
 429  
 430  
 431  /**
 432   * Class for loading questions according to various criteria.
 433   *
 434   * @copyright  2009 The Open University
 435   * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
 436   */
 437  class question_finder implements cache_data_source {
 438      /** @var question_finder the singleton instance of this class. */
 439      protected static $questionfinder = null;
 440  
 441      /**
 442       * @return question_finder a question finder.
 443       */
 444      public static function get_instance() {
 445          if (is_null(self::$questionfinder)) {
 446              self::$questionfinder = new question_finder();
 447          }
 448          return self::$questionfinder;
 449      }
 450  
 451      /* See cache_data_source::get_instance_for_cache. */
 452      public static function get_instance_for_cache(cache_definition $definition) {
 453          return self::get_instance();
 454      }
 455  
 456      /**
 457       * @return get the question definition cache we are using.
 458       */
 459      protected function get_data_cache() {
 460          // Do not double cache here because it may break cache resetting.
 461          return cache::make('core', 'questiondata');
 462      }
 463  
 464      /**
 465       * This method needs to be called whenever a question is edited.
 466       */
 467      public function uncache_question($questionid) {
 468          $this->get_data_cache()->delete($questionid);
 469      }
 470  
 471      /**
 472       * Load a question definition data from the database. The data will be
 473       * returned as a plain stdClass object.
 474       * @param int $questionid the id of the question to load.
 475       * @return object question definition loaded from the database.
 476       */
 477      public function load_question_data($questionid) {
 478          return $this->get_data_cache()->get($questionid);
 479      }
 480  
 481      /**
 482       * Get the ids of all the questions in a list of categories.
 483       * @param array $categoryids either a categoryid, or a comma-separated list
 484       *      category ids, or an array of them.
 485       * @param string $extraconditions extra conditions to AND with the rest of
 486       *      the where clause. Must use named parameters.
 487       * @param array $extraparams any parameters used by $extraconditions.
 488       * @return array questionid => questionid.
 489       */
 490      public function get_questions_from_categories($categoryids, $extraconditions,
 491              $extraparams = array()) {
 492          global $DB;
 493  
 494          list($qcsql, $qcparams) = $DB->get_in_or_equal($categoryids, SQL_PARAMS_NAMED, 'qc');
 495  
 496          if ($extraconditions) {
 497              $extraconditions = ' AND (' . $extraconditions . ')';
 498          }
 499  
 500          return $DB->get_records_select_menu('question',
 501                  "category {$qcsql}
 502                   AND parent = 0
 503                   AND hidden = 0
 504                   {$extraconditions}", $qcparams + $extraparams, '', 'id,id AS id2');
 505      }
 506  
 507      /**
 508       * Get the ids of all the questions in a list of categories, with the number
 509       * of times they have already been used in a given set of usages.
 510       *
 511       * The result array is returned in order of increasing (count previous uses).
 512       *
 513       * @param array $categoryids an array question_category ids.
 514       * @param qubaid_condition $qubaids which question_usages to count previous uses from.
 515       * @param string $extraconditions extra conditions to AND with the rest of
 516       *      the where clause. Must use named parameters.
 517       * @param array $extraparams any parameters used by $extraconditions.
 518       * @return array questionid => count of number of previous uses.
 519       */
 520      public function get_questions_from_categories_with_usage_counts($categoryids,
 521              qubaid_condition $qubaids, $extraconditions = '', $extraparams = array()) {
 522          return $this->get_questions_from_categories_and_tags_with_usage_counts(
 523                  $categoryids, $qubaids, $extraconditions, $extraparams);
 524      }
 525  
 526      /**
 527       * Get the ids of all the questions in a list of categories that have ALL the provided tags,
 528       * with the number of times they have already been used in a given set of usages.
 529       *
 530       * The result array is returned in order of increasing (count previous uses).
 531       *
 532       * @param array $categoryids an array of question_category ids.
 533       * @param qubaid_condition $qubaids which question_usages to count previous uses from.
 534       * @param string $extraconditions extra conditions to AND with the rest of
 535       *      the where clause. Must use named parameters.
 536       * @param array $extraparams any parameters used by $extraconditions.
 537       * @param array $tagids an array of tag ids
 538       * @return array questionid => count of number of previous uses.
 539       */
 540      public function get_questions_from_categories_and_tags_with_usage_counts($categoryids,
 541              qubaid_condition $qubaids, $extraconditions = '', $extraparams = array(), $tagids = array()) {
 542          global $DB;
 543  
 544          list($qcsql, $qcparams) = $DB->get_in_or_equal($categoryids, SQL_PARAMS_NAMED, 'qc');
 545  
 546          $select = "q.id, (SELECT COUNT(1)
 547                              FROM " . $qubaids->from_question_attempts('qa') . "
 548                             WHERE qa.questionid = q.id AND " . $qubaids->where() . "
 549                           ) AS previous_attempts";
 550          $from   = "{question} q";
 551          $where  = "q.category {$qcsql}
 552                 AND q.parent = 0
 553                 AND q.hidden = 0";
 554          $params = $qcparams;
 555  
 556          if (!empty($tagids)) {
 557              // We treat each additional tag as an AND condition rather than
 558              // an OR condition.
 559              //
 560              // For example, if the user filters by the tags "foo" and "bar" then
 561              // we reduce the question list to questions that are tagged with both
 562              // "foo" AND "bar". Any question that does not have ALL of the specified
 563              // tags will be omitted.
 564              list($tagsql, $tagparams) = $DB->get_in_or_equal($tagids, SQL_PARAMS_NAMED, 'ti');
 565              $tagparams['tagcount'] = count($tagids);
 566              $tagparams['questionitemtype'] = 'question';
 567              $tagparams['questioncomponent'] = 'core_question';
 568              $where .= " AND q.id IN (SELECT ti.itemid
 569                                         FROM {tag_instance} ti
 570                                        WHERE ti.itemtype = :questionitemtype
 571                                              AND ti.component = :questioncomponent
 572                                              AND ti.tagid {$tagsql}
 573                                     GROUP BY ti.itemid
 574                                       HAVING COUNT(itemid) = :tagcount)";
 575              $params += $tagparams;
 576          }
 577  
 578          if ($extraconditions) {
 579              $extraconditions = ' AND (' . $extraconditions . ')';
 580          }
 581  
 582          return $DB->get_records_sql_menu("SELECT $select
 583                                              FROM $from
 584                                             WHERE $where $extraconditions
 585                                          ORDER BY previous_attempts",
 586                  $qubaids->from_where_params() + $params + $extraparams);
 587      }
 588  
 589      /* See cache_data_source::load_for_cache. */
 590      public function load_for_cache($questionid) {
 591          global $DB;
 592          $questiondata = $DB->get_record_sql('
 593                                      SELECT q.*, qc.contextid
 594                                      FROM {question} q
 595                                      JOIN {question_categories} qc ON q.category = qc.id
 596                                      WHERE q.id = :id', array('id' => $questionid), MUST_EXIST);
 597          get_question_options($questiondata);
 598          return $questiondata;
 599      }
 600  
 601      /* See cache_data_source::load_many_for_cache. */
 602      public function load_many_for_cache(array $questionids) {
 603          global $DB;
 604          list($idcondition, $params) = $DB->get_in_or_equal($questionids);
 605          $questiondata = $DB->get_records_sql('
 606                                              SELECT q.*, qc.contextid
 607                                              FROM {question} q
 608                                              JOIN {question_categories} qc ON q.category = qc.id
 609                                              WHERE q.id ' . $idcondition, $params);
 610  
 611          foreach ($questionids as $id) {
 612              if (!array_key_exists($id, $questiondata)) {
 613                  throw new dml_missing_record_exception('question', '', array('id' => $id));
 614              }
 615              get_question_options($questiondata[$id]);
 616          }
 617          return $questiondata;
 618      }
 619  }