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Differences Between: [Versions 400 and 401] [Versions 400 and 402] [Versions 400 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   * Matching question definition class.
  19   *
  20   * @package   qtype_randomsamatch
  21   * @copyright 2013 Jean-Michel Vedrine
  22   * @license   http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
  23   */
  24  
  25  
  26  defined('MOODLE_INTERNAL') || die();
  27  
  28  require_once($CFG->dirroot . '/question/type/match/question.php');
  29  
  30  /**
  31   * Represents a randomsamatch question.
  32   *
  33   * @copyright 22013 Jean-Michel Vedrine
  34   * @license   http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
  35   */
  36  class qtype_randomsamatch_question extends qtype_match_question {
  37      /** @var qtype_randomsamatch_question_loader helper for loading the shortanswer questions. */
  38      public $questionsloader;
  39  
  40      public function start_attempt(question_attempt_step $step, $variant) {
  41          $saquestions = $this->questionsloader->load_questions();
  42          foreach ($saquestions as $wrappedquestion) {
  43              // Store and save stem text and format.
  44              $this->stems[$wrappedquestion->id] = $wrappedquestion->questiontext;
  45              $this->stemformat[$wrappedquestion->id] = $wrappedquestion->questiontextformat;
  46              $step->set_qt_var('_stem_' . $wrappedquestion->id, $this->stems[$wrappedquestion->id]);
  47              $step->set_qt_var('_stemformat_' . $wrappedquestion->id, $this->stemformat[$wrappedquestion->id]);
  48  
  49              // Find, store and save right choice id.
  50              $key = $this->find_right_answer($wrappedquestion);
  51              $this->right[$wrappedquestion->id] = $key;
  52              $step->set_qt_var('_right_' . $wrappedquestion->id, $key);
  53              // No need to save saquestions, it will be saved by parent class in _stemorder.
  54          }
  55  
  56          // Save all the choices.
  57          foreach ($this->choices as $key => $answer) {
  58              $step->set_qt_var('_choice_' . $key, $answer);
  59          }
  60  
  61          parent::start_attempt($step, $variant);
  62      }
  63  
  64      /**
  65       * Find the corresponding choice id of the first correct answer of a shortanswer question.
  66       * choice is added to the randomsamatch question if it doesn't already exist.
  67       * @param object $wrappedquestion short answer question.
  68       * @return int correct choice id.
  69       */
  70      public function find_right_answer($wrappedquestion) {
  71          // We only take into account *one* (the first) correct answer.
  72          while ($answer = array_shift($wrappedquestion->answers)) {
  73              if (!question_state::graded_state_for_fraction(
  74                      $answer->fraction)->is_incorrect()) {
  75                  // Store this answer as a choice, only if this is a new one.
  76                  $key = array_search($answer->answer, $this->choices);
  77                  if ($key === false) {
  78                      $key = $answer->id;
  79                      $this->choices[$key] = $answer->answer;
  80                  }
  81                  return $key;
  82              }
  83          }
  84          // We should never get there.
  85          throw new coding_exception('shortanswerquestionwithoutrightanswer', $wrappedquestion->id);
  86  
  87      }
  88  
  89      public function apply_attempt_state(question_attempt_step $step) {
  90          $saquestions = explode(',', $step->get_qt_var('_stemorder'));
  91          foreach ($saquestions as $questionid) {
  92              $this->stems[$questionid] = $step->get_qt_var('_stem_' . $questionid);
  93              $this->stemformat[$questionid] = $step->get_qt_var('_stemformat_' . $questionid);
  94              $key = $step->get_qt_var('_right_' . $questionid);
  95              $this->right[$questionid] = $key;
  96              $this->choices[$key] = $step->get_qt_var('_choice_' . $key);
  97          }
  98          parent::apply_attempt_state($step);
  99      }
 100  }
 101  
 102  /**
 103   * This class is responsible for loading the questions that a question needs from the database.
 104   *
 105   * @copyright  2013 Jean-Michel vedrine
 106   * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
 107   */
 108  class qtype_randomsamatch_question_loader {
 109      /** @var array hold available shortanswers questionid to choose from. */
 110      protected $availablequestions;
 111      /** @var int how many questions to load. */
 112      protected $choose;
 113  
 114      /**
 115       * Constructor
 116       * @param array $availablequestions array of available question ids.
 117       * @param int $choose how many questions to load.
 118       */
 119      public function __construct($availablequestions, $choose) {
 120          $this->availablequestions = $availablequestions;
 121          $this->choose = $choose;
 122      }
 123  
 124      /**
 125       * Choose and load the desired number of questions.
 126       * @return array of short answer questions.
 127       */
 128      public function load_questions() {
 129          if ($this->choose > count($this->availablequestions)) {
 130              throw new coding_exception('notenoughtshortanswerquestions');
 131          }
 132  
 133          $questionids = draw_rand_array($this->availablequestions, $this->choose);
 134          $questions = array();
 135          foreach ($questionids as $questionid) {
 136              $questions[] = question_bank::load_question($questionid);
 137          }
 138          return $questions;
 139      }
 140  }