questiontype.php

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<?php  // $Id: questiontype.php,v 1.32.2.11 2009/01/23 02:19:36 tjhunt Exp $

/////////////
/// MATCH ///
/////////////

/// QUESTION TYPE CLASS //////////////////
/**
 * @package questionbank
 * @subpackage questiontypes
 */
class question_match_qtype extends default_questiontype {

    function name() {
        return 'match';
    }

    function get_question_options(&$question) {
        $question->options = get_record('question_match', 'question', $question->id);
        $question->options->subquestions = get_records('question_match_sub', 'question', $question->id, 'id ASC');
        return true;
    }

    function save_question_options($question) {
        $result = new stdClass;

        if (!$oldsubquestions = get_records("question_match_sub", "question", $question->id, "id ASC")) {
            $oldsubquestions = array();
        }

        // $subquestions will be an array with subquestion ids
        $subquestions = array();

        // Insert all the new question+answer pairs
        foreach ($question->subquestions as $key => $questiontext) {
            $questiontext = trim($questiontext);
            $answertext = trim($question->subanswers[$key]);
            if ($questiontext != '' || $answertext != '') {
                if ($subquestion = array_shift($oldsubquestions)) {  // Existing answer, so reuse it
                    $subquestion->questiontext = $questiontext;
                    $subquestion->answertext   = $answertext;
                    if (!update_record("question_match_sub", $subquestion)) {
                        $result->error = "Could not insert match subquestion! (id=$subquestion->id)";
                        return $result;
                    }
                } else {
                    $subquestion = new stdClass;
                    // Determine a unique random code
                    $subquestion->code = rand(1,999999999);
                    while (record_exists('question_match_sub', 'code', $subquestion->code, 'question', $question->id)) {
                        $subquestion->code = rand();
                    }
                    $subquestion->question = $question->id;
                    $subquestion->questiontext = $questiontext;
                    $subquestion->answertext   = $answertext;
                    if (!$subquestion->id = insert_record("question_match_sub", $subquestion)) {
                        $result->error = "Could not insert match subquestion!";
                        return $result;
                    }
                }
                $subquestions[] = $subquestion->id;
            }
            if ($questiontext != '' && $answertext == '') {
                $result->notice = get_string('nomatchinganswer', 'quiz', $questiontext);
            }
        }

        // delete old subquestions records
        if (!empty($oldsubquestions)) {
            foreach($oldsubquestions as $os) {
                delete_records('question_match_sub', 'id', $os->id);
            }
        }

        if ($options = get_record("question_match", "question", $question->id)) {
            $options->subquestions = implode(",",$subquestions);
            $options->shuffleanswers = $question->shuffleanswers;
            if (!update_record("question_match", $options)) {
                $result->error = "Could not update match options! (id=$options->id)";
                return $result;
            }
        } else {
            unset($options);
            $options->question = $question->id;
            $options->subquestions = implode(",",$subquestions);
            $options->shuffleanswers = $question->shuffleanswers;
            if (!insert_record("question_match", $options)) {
                $result->error = "Could not insert match options!";
                return $result;
            }
        }

        if (!empty($result->notice)) {
            return $result;
        }

        if (count($subquestions) < 3) {
            $result->notice = get_string('notenoughanswers', 'quiz', 3);
            return $result;
        }

        return true;
    }

    /**
    * Deletes question from the question-type specific tables
    *
    * @return boolean Success/Failure
    * @param integer $question->id
    */
    function delete_question($questionid) {
        delete_records("question_match", "question", $questionid);
        delete_records("question_match_sub", "question", $questionid);
        return true;
    }

    function create_session_and_responses(&$question, &$state, $cmoptions, $attempt) {
        if (!$state->options->subquestions = get_records('question_match_sub', 'question', $question->id, 'id ASC')) {
            notify('Error: Missing subquestions!');
            return false;
        }

        foreach ($state->options->subquestions as $key => $subquestion) {
            // This seems rather over complicated, but it is useful for the
            // randomsamatch questiontype, which can then inherit the print
            // and grading functions. This way it is possible to define multiple
            // answers per question, each with different marks and feedback.
            $answer = new stdClass();
            $answer->id       = $subquestion->code;
            $answer->answer   = $subquestion->answertext;
            $answer->fraction = 1.0;
            $state->options->subquestions[$key]->options->answers[$subquestion->code] = clone($answer);

            $state->responses[$key] = '';
        }

        // Shuffle the answers if required
        if ($cmoptions->shuffleanswers and $question->options->shuffleanswers) {
           $state->options->subquestions = swapshuffle_assoc($state->options->subquestions);
        }

        return true;
    }

    function restore_session_and_responses(&$question, &$state) {
        // The serialized format for matching questions is a comma separated
        // list of question answer pairs (e.g. 1-1,2-3,3-2), where the ids of
        // both refer to the id in the table question_match_sub.
        $responses = explode(',', $state->responses['']);
        $responses = array_map(create_function('$val', 'return explode("-", $val);'), $responses);

        if (!$questions = get_records('question_match_sub', 'question', $question->id, 'id ASC')) {
           notify('Error: Missing subquestions!');
           return false;
        }

        // Restore the previous responses and place the questions into the state options
        $state->responses = array();
        $state->options->subquestions = array();
        foreach ($responses as $response) {
            $state->responses[$response[0]] = $response[1];
            $state->options->subquestions[$response[0]] = $questions[$response[0]];
        }

        foreach ($state->options->subquestions as $key => $subquestion) {
            // This seems rather over complicated, but it is useful for the
            // randomsamatch questiontype, which can then inherit the print
            // and grading functions. This way it is possible to define multiple
            // answers per question, each with different marks and feedback.
            $answer = new stdClass();
            $answer->id       = $subquestion->code;
            $answer->answer   = $subquestion->answertext;
            $answer->fraction = 1.0;
            $state->options->subquestions[$key]->options->answers[$subquestion->code] = clone($answer);
        }

        return true;
    }

    function save_session_and_responses(&$question, &$state) {
         $subquestions = &$state->options->subquestions;

        // Prepare an array to help when disambiguating equal answers.
        $answertexts = array();
        foreach ($subquestions as $subquestion) {
            $ans = reset($subquestion->options->answers);
            $answertexts[$ans->id] = $ans->answer;
        }

        // Serialize responses
        $responses = array();
        foreach ($subquestions as $key => $subquestion) {
            $response = 0;
            if ($subquestion->questiontext !== '' && !is_null($subquestion->questiontext)) {
                if ($state->responses[$key]) {
                    $response = $state->responses[$key];
                    if (!array_key_exists($response, $subquestion->options->answers)) {
                        // If student's answer did not match by id, but there may be
                        // two answers with the same text, but different ids,
                        // so we need to try matching the answer text.
                        $expected_answer = reset($subquestion->options->answers);
                        if ($answertexts[$response] == $expected_answer->answer) {
                            $response = $expected_answer->id;
                            $state->responses[$key] = $response;
                        }
                    }
                }
            }
            $responses[] = $key.'-'.$response;
        }
        $responses = implode(',', $responses);

        // Set the legacy answer field
        if (!set_field('question_states', 'answer', $responses, 'id', $state->id)) {
            return false;
        }
        return true;
    }

    function get_correct_responses(&$question, &$state) {
        $responses = array();
        foreach ($state->options->subquestions as $sub) {
            foreach ($sub->options->answers as $answer) {
                if (1 == $answer->fraction && $sub->questiontext != '' && !is_null($sub->questiontext)) {
                    $responses[$sub->id] = $answer->id;
                }
            }
        }
        return empty($responses) ? null : $responses;
    }

    function print_question_formulation_and_controls(&$question, &$state, $cmoptions, $options) {
        global $CFG;
        $subquestions   = $state->options->subquestions;
        $correctanswers = $this->get_correct_responses($question, $state);
        $nameprefix     = $question->name_prefix;
        $answers        = array(); // Answer choices formatted ready for output.
        $allanswers     = array(); // This and the next used to detect identical answers
        $answerids      = array(); // and adjust ids.
        $responses      = &$state->responses;

        // Prepare a list of answers, removing duplicates.
        foreach ($subquestions as $subquestion) {
            foreach ($subquestion->options->answers as $ans) {
                $allanswers[$ans->id] = $ans->answer;
                if (!in_array($ans->answer, $answers)) {
                    $answers[$ans->id] = strip_tags(format_string($ans->answer, false));
                    $answerids[$ans->answer] = $ans->id;
                }
            }
        }

        // Fix up the ids of any responses that point the the eliminated duplicates.
        foreach ($responses as $subquestionid => $ignored) {
            if ($responses[$subquestionid]) {
                $responses[$subquestionid] = $answerids[$allanswers[$responses[$subquestionid]]];
            }
        }
        foreach ($correctanswers as $subquestionid => $ignored) {
            $correctanswers[$subquestionid] = $answerids[$allanswers[$correctanswers[$subquestionid]]];
        }

        // Shuffle the answers
        $answers = draw_rand_array($answers, count($answers));

        // Print formulation
        $questiontext = $this->format_text($question->questiontext,
                $question->questiontextformat, $cmoptions);
        $image = get_question_image($question);

        // Print the input controls
        foreach ($subquestions as $key => $subquestion) {
            if ($subquestion->questiontext !== '' && !is_null($subquestion->questiontext)) {
                // Subquestion text:
                $a = new stdClass;
                $a->text = $this->format_text($subquestion->questiontext,
                        $question->questiontextformat, $cmoptions);

                // Drop-down list:
                $menuname = $nameprefix.$subquestion->id;
                $response = isset($state->responses[$subquestion->id])
                            ? $state->responses[$subquestion->id] : '0';

                $a->class = ' ';
                $a->feedbackimg = ' ';

                if ($options->readonly and $options->correct_responses) {
                    if (isset($correctanswers[$subquestion->id])
                            and ($correctanswers[$subquestion->id] == $response)) {
                        $correctresponse = 1;
                    } else {
                        $correctresponse = 0;
                    }

                    if ($options->feedback && $response) {
                        $a->class = question_get_feedback_class($correctresponse);
                        $a->feedbackimg = question_get_feedback_image($correctresponse);
                    }
                }

                $a->control = choose_from_menu($answers, $menuname, $response, 'choose',
                                               '', 0, true, $options->readonly);

                // Neither the editing interface or the database allow to provide
                // fedback for this question type.
                // However (as was pointed out in bug bug 3294) the randomsamatch
                // type which reuses this method can have feedback defined for
                // the wrapped shortanswer questions.
                //if ($options->feedback
                // && !empty($subquestion->options->answers[$responses[$key]]->feedback)) {
                //    print_comment($subquestion->options->answers[$responses[$key]]->feedback);
                //}

                $anss[] = $a;
            }
        }
        include("$CFG->dirroot/question/type/match/display.html");
    }

    function grade_responses(&$question, &$state, $cmoptions) {
        $subquestions = &$state->options->subquestions;
        $responses    = &$state->responses;

        // Prepare an array to help when disambiguating equal answers.
        $answertexts = array();
        foreach ($subquestions as $subquestion) {
            $ans = reset($subquestion->options->answers);
            $answertexts[$ans->id] = $ans->answer;
        }

        // Add up the grades from each subquestion.
        $sumgrade = 0;
        $totalgrade = 0;
        foreach ($subquestions as $key => $sub) {
            if ($sub->questiontext !== '' && !is_null($sub->questiontext)) {
                $totalgrade += 1;
                $response = $responses[$key];
                if ($response && !array_key_exists($response, $sub->options->answers)) {
                    // If studen's answer did not match by id, but there may be
                    // two answers with the same text, but different ids,
                    // so we need to try matching the answer text.
                    $expected_answer = reset($sub->options->answers);
                    if ($answertexts[$response] == $expected_answer->answer) {
                        $response = $expected_answer->id;
                    }
                }
                if (array_key_exists($response, $sub->options->answers)) {
                    $sumgrade += $sub->options->answers[$response]->fraction;
                }
            }
        }

        $state->raw_grade = $sumgrade/$totalgrade;
        if (empty($state->raw_grade)) {
            $state->raw_grade = 0;
        }

        // Make sure we don't assign negative or too high marks
        $state->raw_grade = min(max((float) $state->raw_grade,
                            0.0), 1.0) * $question->maxgrade;
        $state->penalty = $question->penalty * $question->maxgrade;