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   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   * Question type class for the random question type.
  19   *
  20   * @package    qtype
  21   * @subpackage random
  22   * @copyright  1999 onwards Martin Dougiamas  {@link http://moodle.com}
  23   * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
  24   */
  25  
  26  
  27  defined('MOODLE_INTERNAL') || die();
  28  
  29  require_once($CFG->dirroot . '/question/type/questiontypebase.php');
  30  
  31  
  32  /**
  33   * The random question type.
  34   *
  35   * This question type does not have a question definition class, nor any
  36   * renderers. When you load a question of this type, it actually loads a
  37   * question chosen randomly from a particular category in the question bank.
  38   *
  39   * @copyright  1999 onwards Martin Dougiamas  {@link http://moodle.com}
  40   * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
  41   */
  42  class qtype_random extends question_type {
  43      /** @var string comma-separated list of qytpe names not to select, can be used in SQL. */
  44      protected $excludedqtypes = null;
  45  
  46      /** @var string comma-separated list of manually graded qytpe names, can be used in SQL. */
  47      protected $manualqtypes = null;
  48  
  49      /**
  50       * Cache of availabe question ids from a particular category.
  51       * @var array two-dimensional array. The first key is a category id, the
  52       * second key is wether subcategories should be included.
  53       */
  54      private $availablequestionsbycategory = array();
  55  
  56      public function menu_name() {
  57          // Don't include this question type in the 'add new question' menu.
  58          return false;
  59      }
  60  
  61      public function is_manual_graded() {
  62          return true;
  63      }
  64  
  65      public function is_usable_by_random() {
  66          return false;
  67      }
  68  
  69      public function is_question_manual_graded($question, $otherquestionsinuse) {
  70          global $DB;
  71          // We take our best shot at working whether a particular question is manually
  72          // graded follows: We look to see if any of the questions that this random
  73          // question might select if of a manually graded type. If a category contains
  74          // a mixture of manual and non-manual questions, and if all the attempts so
  75          // far selected non-manual ones, this will give the wrong answer, but we
  76          // don't care. Even so, this is an expensive calculation!
  77          $this->init_qtype_lists();
  78          if (!$this->manualqtypes) {
  79              return false;
  80          }
  81          if ($question->questiontext) {
  82              $categorylist = question_categorylist($question->category);
  83          } else {
  84              $categorylist = array($question->category);
  85          }
  86          list($qcsql, $qcparams) = $DB->get_in_or_equal($categorylist);
  87          // TODO use in_or_equal for $otherquestionsinuse and $this->manualqtypes.
  88          return $DB->record_exists_select('question',
  89                  "category {$qcsql}
  90                       AND parent = 0
  91                       AND hidden = 0
  92                       AND id NOT IN ($otherquestionsinuse)
  93                       AND qtype IN ($this->manualqtypes)", $qcparams);
  94      }
  95  
  96      /**
  97       * This method needs to be called before the ->excludedqtypes and
  98       *      ->manualqtypes fields can be used.
  99       */
 100      protected function init_qtype_lists() {
 101          if (!is_null($this->excludedqtypes)) {
 102              return; // Already done.
 103          }
 104          $excludedqtypes = array();
 105          $manualqtypes = array();
 106          foreach (question_bank::get_all_qtypes() as $qtype) {
 107              $quotedname = "'" . $qtype->name() . "'";
 108              if (!$qtype->is_usable_by_random()) {
 109                  $excludedqtypes[] = $quotedname;
 110              } else if ($qtype->is_manual_graded()) {
 111                  $manualqtypes[] = $quotedname;
 112              }
 113          }
 114          $this->excludedqtypes = implode(',', $excludedqtypes);
 115          $this->manualqtypes = implode(',', $manualqtypes);
 116      }
 117  
 118      public function get_question_options($question) {
 119          return true;
 120      }
 121  
 122      /**
 123       * Random questions always get a question name that is Random (cateogryname).
 124       * This function is a centralised place to calculate that, given the category.
 125       * @param object $category the category this question picks from. (Only ->name is used.)
 126       * @param bool $includesubcategories whether this question also picks from subcategories.
 127       * @return string the name this question should have.
 128       */
 129      public function question_name($category, $includesubcategories) {
 130          if ($includesubcategories) {
 131              $string = 'randomqplusname';
 132          } else {
 133              $string = 'randomqname';
 134          }
 135          return get_string($string, 'qtype_random', shorten_text($category->name, 100));
 136      }
 137  
 138      protected function set_selected_question_name($question, $randomname) {
 139          $a = new stdClass();
 140          $a->randomname = $randomname;
 141          $a->questionname = $question->name;
 142          $question->name = get_string('selectedby', 'qtype_random', $a);
 143      }
 144  
 145      public function save_question($question, $form) {
 146          $form->name = '';
 147  
 148          // In case someone set the question text to true/false in the old style, set it properly.
 149          if ($form->questiontext['text']) {
 150              $form->questiontext['text'] = '1';
 151          } else {
 152              $form->questiontext['text'] = '0';
 153          }
 154          $form->tags = array();
 155  
 156          // Name is not a required field for random questions, but
 157          // parent::save_question Assumes that it is.
 158          return parent::save_question($question, $form);
 159      }
 160  
 161      public function save_question_options($question) {
 162          global $DB;
 163  
 164          // No options, as such, but we set the parent field to the question's
 165          // own id. Setting the parent field has the effect of hiding this
 166          // question in various places.
 167          $updateobject = new stdClass();
 168          $updateobject->id = $question->id;
 169          $updateobject->parent = $question->id;
 170  
 171          // We also force the question name to be 'Random (categoryname)'.
 172          $category = $DB->get_record('question_categories',
 173                  array('id' => $question->category), '*', MUST_EXIST);
 174          $updateobject->name = $this->question_name($category, !empty($question->questiontext));
 175          return $DB->update_record('question', $updateobject);
 176      }
 177  
 178      /**
 179       * During unit tests we need to be able to reset all caches so that each new test starts in a known state.
 180       * Intended for use only for testing. This is a stop gap until we start using the MUC caching api here.
 181       * You need to call this before every test that loads one or more random questions.
 182       */
 183      public function clear_caches_before_testing() {
 184          $this->availablequestionsbycategory = array();
 185      }
 186  
 187      /**
 188       * Get all the usable questions from a particular question category.
 189       *
 190       * @param int $categoryid the id of a question category.
 191       * @param bool whether to include questions from subcategories.
 192       * @param string $questionsinuse comma-separated list of question ids to
 193       *      exclude from consideration.
 194       * @return array of question records.
 195       */
 196      public function get_available_questions_from_category($categoryid, $subcategories) {
 197          if (isset($this->availablequestionsbycategory[$categoryid][$subcategories])) {
 198              return $this->availablequestionsbycategory[$categoryid][$subcategories];
 199          }
 200  
 201          $this->init_qtype_lists();
 202          if ($subcategories) {
 203              $categoryids = question_categorylist($categoryid);
 204          } else {
 205              $categoryids = array($categoryid);
 206          }
 207  
 208          $questionids = question_bank::get_finder()->get_questions_from_categories(
 209                  $categoryids, 'qtype NOT IN (' . $this->excludedqtypes . ')');
 210          $this->availablequestionsbycategory[$categoryid][$subcategories] = $questionids;
 211          return $questionids;
 212      }
 213  
 214      public function make_question($questiondata) {
 215          return $this->choose_other_question($questiondata, array());
 216      }
 217  
 218      /**
 219       * Load the definition of another question picked randomly by this question.
 220       * @param object       $questiondata the data defining a random question.
 221       * @param array        $excludedquestions of question ids. We will no pick any question whose id is in this list.
 222       * @param bool         $allowshuffle      if false, then any shuffle option on the selected quetsion is disabled.
 223       * @param null|integer $forcequestionid   if not null then force the picking of question with id $forcequestionid.
 224       * @throws coding_exception
 225       * @return question_definition|null the definition of the question that was
 226       *      selected, or null if no suitable question could be found.
 227       */
 228      public function choose_other_question($questiondata, $excludedquestions, $allowshuffle = true, $forcequestionid = null) {
 229          $available = $this->get_available_questions_from_category($questiondata->category,
 230                  !empty($questiondata->questiontext));
 231          shuffle($available);
 232  
 233          if ($forcequestionid !== null) {
 234              $forcedquestionkey = array_search($forcequestionid, $available);
 235              if ($forcedquestionkey !== false) {
 236                  unset($available[$forcedquestionkey]);
 237                  array_unshift($available, $forcequestionid);
 238              } else {
 239                  throw new coding_exception('thisquestionidisnotavailable', $forcequestionid);
 240              }
 241          }
 242  
 243          foreach ($available as $questionid) {
 244              if (in_array($questionid, $excludedquestions)) {
 245                  continue;
 246              }
 247  
 248              $question = question_bank::load_question($questionid, $allowshuffle);
 249              $this->set_selected_question_name($question, $questiondata->name);
 250              return $question;
 251          }
 252          return null;
 253      }
 254  
 255      public function get_random_guess_score($questiondata) {
 256          return null;
 257      }
 258  }