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Developer Documentation

See Release Notes

  • Bug fixes for general core bugs in 4.2.x will end 22 April 2024 (12 months).
  • Bug fixes for security issues in 4.2.x will end 7 October 2024 (18 months).
  • PHP version: minimum PHP 8.0.0 Note: minimum PHP version has increased since Moodle 4.1. PHP 8.1.x is supported too.

Differences Between: [Versions 310 and 402] [Versions 311 and 402] [Versions 39 and 402] [Versions 400 and 402] [Versions 401 and 402]

   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   * The default questiontype class.
  19   *
  20   * @package    moodlecore
  21   * @subpackage questiontypes
  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($CFG->dirroot . '/question/engine/lib.php');
  30  require_once($CFG->libdir . '/questionlib.php');
  31  
  32  
  33  /**
  34   * This is the base class for Moodle question types.
  35   *
  36   * There are detailed comments on each method, explaining what the method is
  37   * for, and the circumstances under which you might need to override it.
  38   *
  39   * Note: the questiontype API should NOT be considered stable yet. Very few
  40   * question types have been produced yet, so we do not yet know all the places
  41   * where the current API is insufficient. I would rather learn from the
  42   * experiences of the first few question type implementors, and improve the
  43   * interface to meet their needs, rather the freeze the API prematurely and
  44   * condem everyone to working round a clunky interface for ever afterwards.
  45   *
  46   * @copyright  1999 onwards Martin Dougiamas {@link http://moodle.com}
  47   * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
  48   */
  49  class question_type {
  50      protected $fileoptions = array(
  51          'subdirs' => true,
  52          'maxfiles' => -1,
  53          'maxbytes' => 0,
  54      );
  55  
  56      public function __construct() {
  57      }
  58  
  59      /**
  60       * @return string the name of this question type.
  61       */
  62      public function name() {
  63          return substr(get_class($this), 6);
  64      }
  65  
  66      /**
  67       * @return string the full frankenstyle name for this plugin.
  68       */
  69      public function plugin_name() {
  70          return get_class($this);
  71      }
  72  
  73      /**
  74       * @return string the name of this question type in the user's language.
  75       * You should not need to override this method, the default behaviour should be fine.
  76       */
  77      public function local_name() {
  78          return get_string('pluginname', $this->plugin_name());
  79      }
  80  
  81      /**
  82       * The name this question should appear as in the create new question
  83       * dropdown. Override this method to return false if you don't want your
  84       * question type to be createable, for example if it is an abstract base type,
  85       * otherwise, you should not need to override this method.
  86       *
  87       * @return mixed the desired string, or false to hide this question type in the menu.
  88       */
  89      public function menu_name() {
  90          return $this->local_name();
  91      }
  92  
  93      /**
  94       * @return bool override this to return false if this is not really a
  95       *      question type, for example the description question type is not
  96       *      really a question type.
  97       */
  98      public function is_real_question_type() {
  99          return true;
 100      }
 101  
 102      /**
 103       * @return bool true if this question type sometimes requires manual grading.
 104       */
 105      public function is_manual_graded() {
 106          return false;
 107      }
 108  
 109      /**
 110       * @param object $question a question of this type.
 111       * @param string $otherquestionsinuse comma-separate list of other question ids in this attempt.
 112       * @return bool true if a particular instance of this question requires manual grading.
 113       */
 114      public function is_question_manual_graded($question, $otherquestionsinuse) {
 115          return $this->is_manual_graded();
 116      }
 117  
 118      /**
 119       * @return bool true if this question type can be used by the random question type.
 120       */
 121      public function is_usable_by_random() {
 122          return true;
 123      }
 124  
 125      /**
 126       * Whether this question type can perform a frequency analysis of student
 127       * responses.
 128       *
 129       * If this method returns true, you must implement the get_possible_responses
 130       * method, and the question_definition class must implement the
 131       * classify_response method.
 132       *
 133       * @return bool whether this report can analyse all the student responses
 134       * for things like the quiz statistics report.
 135       */
 136      public function can_analyse_responses() {
 137          // This works in most cases.
 138          return !$this->is_manual_graded();
 139      }
 140  
 141      /**
 142       * @return whether the question_answers.answer field needs to have
 143       * restore_decode_content_links_worker called on it.
 144       */
 145      public function has_html_answers() {
 146          return false;
 147      }
 148  
 149      /**
 150       * If your question type has a table that extends the question table, and
 151       * you want the base class to automatically save, backup and restore the extra fields,
 152       * override this method to return an array wherer the first element is the table name,
 153       * and the subsequent entries are the column names (apart from id and questionid).
 154       *
 155       * @return mixed array as above, or null to tell the base class to do nothing.
 156       */
 157      public function extra_question_fields() {
 158          return null;
 159      }
 160  
 161      /**
 162       * If you use extra_question_fields, overload this function to return question id field name
 163       *  in case you table use another name for this column
 164       */
 165      public function questionid_column_name() {
 166          return 'questionid';
 167      }
 168  
 169      /**
 170       * If your question type has a table that extends the question_answers table,
 171       * make this method return an array wherer the first element is the table name,
 172       * and the subsequent entries are the column names (apart from id and answerid).
 173       *
 174       * @return mixed array as above, or null to tell the base class to do nothing.
 175       */
 176      public function extra_answer_fields() {
 177          return null;
 178      }
 179  
 180      /**
 181       * If the quetsion type uses files in responses, then this method should
 182       * return an array of all the response variables that might have corresponding
 183       * files. For example, the essay qtype returns array('attachments', 'answers').
 184       *
 185       * @return array response variable names that may have associated files.
 186       */
 187      public function response_file_areas() {
 188          return array();
 189      }
 190  
 191      /**
 192       * Return an instance of the question editing form definition. This looks for a
 193       * class called edit_{$this->name()}_question_form in the file
 194       * question/type/{$this->name()}/edit_{$this->name()}_question_form.php
 195       * and if it exists returns an instance of it.
 196       *
 197       * @param string $submiturl passed on to the constructor call.
 198       * @return object an instance of the form definition, or null if one could not be found.
 199       */
 200      public function create_editing_form($submiturl, $question, $category,
 201              $contexts, $formeditable) {
 202          global $CFG;
 203          require_once($CFG->dirroot . '/question/type/edit_question_form.php');
 204          $definitionfile = $CFG->dirroot . '/question/type/' . $this->name() .
 205                  '/edit_' . $this->name() . '_form.php';
 206          if (!is_readable($definitionfile) || !is_file($definitionfile)) {
 207              throw new coding_exception($this->plugin_name() .
 208                      ' is missing the definition of its editing formin file ' .
 209                      $definitionfile . '.');
 210          }
 211          require_once($definitionfile);
 212          $classname = $this->plugin_name() . '_edit_form';
 213          if (!class_exists($classname)) {
 214              throw new coding_exception($this->plugin_name() .
 215                      ' does not define the class ' . $this->plugin_name() .
 216                      '_edit_form.');
 217          }
 218          return new $classname($submiturl, $question, $category, $contexts, $formeditable);
 219      }
 220  
 221      /**
 222       * @return string the full path of the folder this plugin's files live in.
 223       */
 224      public function plugin_dir() {
 225          global $CFG;
 226          return $CFG->dirroot . '/question/type/' . $this->name();
 227      }
 228  
 229      /**
 230       * @return string the URL of the folder this plugin's files live in.
 231       */
 232      public function plugin_baseurl() {
 233          global $CFG;
 234          return $CFG->wwwroot . '/question/type/' . $this->name();
 235      }
 236  
 237      /**
 238       * Get extra actions for a question of this type to add to the question bank edit menu.
 239       *
 240       * This method is called if the {@link edit_menu_column} is being used in the
 241       * question bank, which it is by default since Moodle 3.8. If applicable for
 242       * your question type, you can return arn array of {@link action_menu_link}s.
 243       * These will be added at the end of the Edit menu for this question.
 244       *
 245       * The $question object passed in will have a hard-to-predict set of fields,
 246       * because the fields present depend on which columns are included in the
 247       * question bank view. However, you can rely on 'id', 'createdby',
 248       * 'contextid', 'hidden' and 'category' (id) being present, and so you
 249       * can call question_has_capability_on without causing performance problems.
 250       *
 251       * @param stdClass $question the available information about the particular question the action is for.
 252       * @return action_menu_link[] any actions you want to add to the Edit menu for this question.
 253       */
 254      public function get_extra_question_bank_actions(stdClass $question): array {
 255          return [];
 256      }
 257  
 258      /**
 259       * This method should be overriden if you want to include a special heading or some other
 260       * html on a question editing page besides the question editing form.
 261       *
 262       * @param question_edit_form $mform a child of question_edit_form
 263       * @param object $question
 264       * @param string $wizardnow is '' for first page.
 265       */
 266      public function display_question_editing_page($mform, $question, $wizardnow) {
 267          global $OUTPUT;
 268          $heading = $this->get_heading(empty($question->id));
 269          echo $OUTPUT->heading_with_help($heading, 'pluginname', $this->plugin_name());
 270          $mform->display();
 271      }
 272  
 273      /**
 274       * Method called by display_question_editing_page and by question.php to get
 275       * heading for breadcrumbs.
 276       *
 277       * @return string the heading
 278       */
 279      public function get_heading($adding = false) {
 280          if ($adding) {
 281              $string = 'pluginnameadding';
 282          } else {
 283              $string = 'pluginnameediting';
 284          }
 285          return get_string($string, $this->plugin_name());
 286      }
 287  
 288      /**
 289       * Set any missing settings for this question to the default values. This is
 290       * called before displaying the question editing form.
 291       *
 292       * @param object $questiondata the question data, loaded from the databsae,
 293       *      or more likely a newly created question object that is only partially
 294       *      initialised.
 295       */
 296      public function set_default_options($questiondata) {
 297      }
 298  
 299      /**
 300       * Return default value for a given form element either from user_preferences table or $default.
 301       *
 302       * @param string $name the name of the form element.
 303       * @param mixed $default default value.
 304       * @return string|null default value for a given  form element.
 305       */
 306      public function get_default_value(string $name, $default): ?string {
 307          return get_user_preferences($this->plugin_name() . '_' . $name, $default ?? '0');
 308      }
 309  
 310      /**
 311       * Save the default value for a given form element in user_preferences table.
 312       *
 313       * @param string $name the name of the value to set.
 314       * @param string $value the setting value.
 315       */
 316      public function set_default_value(string $name, string $value): void {
 317          set_user_preference($this->plugin_name() . '_' . $name, $value);
 318      }
 319  
 320      /**
 321       * Save question defaults when creating new questions.
 322       *
 323       * @param stdClass $fromform data from the form.
 324       */
 325      public function save_defaults_for_new_questions(stdClass $fromform): void {
 326          // Some question types may not make use of the certain form elements, so
 327          // we need to do a check on the following generic form elements. For instance,
 328          // 'defaultmark' is not use in qtype_multianswer and 'penalty' in not used in
 329          // qtype_essay and qtype_recordrtc.
 330          if (isset($fromform->defaultmark)) {
 331              $this->set_default_value('defaultmark', $fromform->defaultmark);
 332          }
 333          if (isset($fromform->penalty)) {
 334              $this->set_default_value('penalty', $fromform->penalty);
 335          }
 336      }
 337  
 338      /**
 339       * Saves (creates or updates) a question.
 340       *
 341       * Given some question info and some data about the answers
 342       * this function parses, organises and saves the question
 343       * It is used by {@link question.php} when saving new data from
 344       * a form, and also by {@link import.php} when importing questions
 345       * This function in turn calls {@link save_question_options}
 346       * to save question-type specific data.
 347       *
 348       * Whether we are saving a new question or updating an existing one can be
 349       * determined by testing !empty($question->id). If it is not empty, we are updating.
 350       *
 351       * The question will be saved in category $form->category.
 352       *
 353       * @param object $question the question object which should be updated. For a
 354       *      new question will be mostly empty.
 355       * @param object $form the object containing the information to save, as if
 356       *      from the question editing form.
 357       * @param object $course not really used any more.
 358       * @return object On success, return the new question object. On failure,
 359       *       return an object as follows. If the error object has an errors field,
 360       *       display that as an error message. Otherwise, the editing form will be
 361       *       redisplayed with validation errors, from validation_errors field, which
 362       *       is itself an object, shown next to the form fields. (I don't think this
 363       *       is accurate any more.)
 364       */
 365      public function save_question($question, $form) {
 366          global $USER, $DB;
 367  
 368          // The actual update/insert done with multiple DB access, so we do it in a transaction.
 369          $transaction = $DB->start_delegated_transaction ();
 370  
 371          list($form->category) = explode(',', $form->category);
 372          $context = $this->get_context_by_category_id($form->category);
 373          $question->category = $form->category;
 374  
 375          // This default implementation is suitable for most
 376          // question types.
 377  
 378          // First, save the basic question itself.
 379          $question->name = trim($form->name);
 380          $question->parent = isset($form->parent) ? $form->parent : 0;
 381          $question->length = $this->actual_number_of_questions($question);
 382          $question->penalty = isset($form->penalty) ? $form->penalty : 0;
 383  
 384          // The trim call below has the effect of casting any strange values received,
 385          // like null or false, to an appropriate string, so we only need to test for
 386          // missing values. Be careful not to break the value '0' here.
 387          if (!isset($form->questiontext['text'])) {
 388              $question->questiontext = '';
 389          } else {
 390              $question->questiontext = trim($form->questiontext['text']);
 391          }
 392          $question->questiontextformat = !empty($form->questiontext['format']) ?
 393                  $form->questiontext['format'] : 0;
 394  
 395          if (empty($form->generalfeedback['text'])) {
 396              $question->generalfeedback = '';
 397          } else {
 398              $question->generalfeedback = trim($form->generalfeedback['text']);
 399          }
 400          $question->generalfeedbackformat = !empty($form->generalfeedback['format']) ?
 401                  $form->generalfeedback['format'] : 0;
 402  
 403          if ($question->name === '') {
 404              $question->name = shorten_text(strip_tags($form->questiontext['text']), 15);
 405              if ($question->name === '') {
 406                  $question->name = '-';
 407              }
 408          }
 409  
 410          if ($question->penalty > 1 or $question->penalty < 0) {
 411              $question->errors['penalty'] = get_string('invalidpenalty', 'question');
 412          }
 413  
 414          if (isset($form->defaultmark)) {
 415              $question->defaultmark = $form->defaultmark;
 416          }
 417  
 418          // Only create a new bank entry if the question is not a new version (New question or duplicating a question).
 419          $questionbankentry = null;
 420          if (isset($question->id)) {
 421              $oldparent = $question->id;
 422              if (!empty($question->id)) {
 423                  // Get the bank entry record where the question is referenced.
 424                  $questionbankentry = get_question_bank_entry($question->id);
 425              }
 426          }
 427  
 428          // Get the bank entry old id (this is when there are questions related with a parent, e.g.: qtype_multianswers).
 429          if (isset($question->oldid)) {
 430              if (!empty($question->oldid)) {
 431                  $questionbankentry = get_question_bank_entry($question->oldid);
 432              }
 433          }
 434  
 435          // Always creates a new question and version record.
 436          // Set the unique code.
 437          $question->stamp = make_unique_id_code();
 438          $question->createdby = $USER->id;
 439          $question->timecreated = time();
 440  
 441          // Idnumber validation.
 442          $question->idnumber = null;
 443          if (isset($form->idnumber)) {
 444              if ((string) $form->idnumber === '') {
 445                  $question->idnumber = null;
 446              } else {
 447                  // While this check already exists in the form validation,
 448                  // this is a backstop preventing unnecessary errors.
 449                  // Only set the idnumber if it has changed and will not cause a unique index violation.
 450                  if (strpos($form->category, ',') !== false) {
 451                      list($category, $categorycontextid) = explode(',', $form->category);
 452                  } else {
 453                      $category = $form->category;
 454                  }
 455                  $params = ['idnumber' => $form->idnumber, 'categoryid' => $category];
 456                  $andcondition = '';
 457                  if (isset($question->id) && isset($questionbankentry->id)) {
 458                      $andcondition = 'AND qbe.id != :notid';
 459                      $params['notid'] = $questionbankentry->id;
 460                  }
 461                  $sql = "SELECT qbe.id
 462                            FROM {question_bank_entries} qbe
 463                           WHERE qbe.idnumber = :idnumber
 464                                 AND qbe.questioncategoryid = :categoryid
 465                             $andcondition";
 466                  if (!$DB->record_exists_sql($sql, $params)) {
 467                      $question->idnumber = $form->idnumber;
 468                  }
 469              }
 470          }
 471  
 472          // Create the question.
 473          $question->id = $DB->insert_record('question', $question);
 474          if (!$questionbankentry) {
 475              // Create a record for question_bank_entries, question_versions and question_references.
 476              $questionbankentry = new \stdClass();
 477              $questionbankentry->questioncategoryid = $form->category;
 478              $questionbankentry->idnumber = $question->idnumber;
 479              $questionbankentry->ownerid = $question->createdby;
 480              $questionbankentry->id = $DB->insert_record('question_bank_entries', $questionbankentry);
 481          } else {
 482              $questionbankentryold = new \stdClass();
 483              $questionbankentryold->id = $questionbankentry->id;
 484              $questionbankentryold->idnumber = $question->idnumber;
 485              $DB->update_record('question_bank_entries', $questionbankentryold);
 486          }
 487  
 488          // Create question_versions records.
 489          $questionversion = new \stdClass();
 490          $questionversion->questionbankentryid = $questionbankentry->id;
 491          $questionversion->questionid = $question->id;
 492          // Get the version and status from the parent question if parent is set.
 493          if (!$question->parent) {
 494              // Get the status field. It comes from the form, but for testing we can.
 495              $status = $form->status ?? $question->status ??
 496                  \core_question\local\bank\question_version_status::QUESTION_STATUS_READY;
 497              $questionversion->version = get_next_version($questionbankentry->id);
 498              $questionversion->status = $status;
 499          } else {
 500              $parentversion = get_question_version($form->parent);
 501              $questionversion->version = $parentversion[array_key_first($parentversion)]->version;
 502              $questionversion->status = $parentversion[array_key_first($parentversion)]->status;
 503          }
 504          $questionversion->id = $DB->insert_record('question_versions', $questionversion);
 505  
 506          // Now, whether we are updating a existing question, or creating a new
 507          // one, we have to do the files processing and update the record.
 508          // Question already exists, update.
 509          $question->modifiedby = $USER->id;
 510          $question->timemodified = time();
 511  
 512          if (!empty($question->questiontext) && !empty($form->questiontext['itemid'])) {
 513              $question->questiontext = file_save_draft_area_files($form->questiontext['itemid'],
 514                      $context->id, 'question', 'questiontext', (int)$question->id,
 515                      $this->fileoptions, $question->questiontext);
 516          }
 517          if (!empty($question->generalfeedback) && !empty($form->generalfeedback['itemid'])) {
 518              $question->generalfeedback = file_save_draft_area_files(
 519                      $form->generalfeedback['itemid'], $context->id,
 520                      'question', 'generalfeedback', (int)$question->id,
 521                      $this->fileoptions, $question->generalfeedback);
 522          }
 523          $DB->update_record('question', $question);
 524  
 525          // Now to save all the answers and type-specific options.
 526          $form->id = $question->id;
 527          $form->qtype = $question->qtype;
 528          $form->questiontext = $question->questiontext;
 529          $form->questiontextformat = $question->questiontextformat;
 530          // Current context.
 531          $form->context = $context;
 532          // Old parent question id is used when there are questions related with a parent, e.g.: qtype_multianswers).
 533          if (isset($oldparent)) {
 534              $form->oldparent = $oldparent;
 535          } else {
 536              $form->oldparent = $question->parent;
 537          }
 538          $result = $this->save_question_options($form);
 539  
 540          if (!empty($result->error)) {
 541              throw new \moodle_exception($result->error);
 542          }
 543  
 544          if (!empty($result->notice)) {
 545              notice($result->notice, "question.php?id={$question->id}");
 546          }
 547  
 548          if (!empty($result->noticeyesno)) {
 549              throw new coding_exception(
 550                      '$result->noticeyesno no longer supported in save_question.');
 551          }
 552  
 553          // Log the creation of this question.
 554          $event = \core\event\question_created::create_from_question_instance($question, $context);
 555          $event->trigger();
 556  
 557          $transaction->allow_commit();
 558  
 559          return $question;
 560      }
 561  
 562      /**
 563       * Saves question-type specific options
 564       *
 565       * This is called by {@link save_question()} to save the question-type specific data
 566       * @return object $result->error or $result->notice
 567       * @param object $question  This holds the information from the editing form,
 568       *      it is not a standard question object.
 569       */
 570      public function save_question_options($question) {
 571          global $DB;
 572          $extraquestionfields = $this->extra_question_fields();
 573  
 574          if (is_array($extraquestionfields)) {
 575              $question_extension_table = array_shift($extraquestionfields);
 576  
 577              $function = 'update_record';
 578              $questionidcolname = $this->questionid_column_name();
 579              $options = $DB->get_record($question_extension_table,
 580                      array($questionidcolname => $question->id));
 581              if (!$options) {
 582                  $function = 'insert_record';
 583                  $options = new stdClass();
 584                  $options->$questionidcolname = $question->id;
 585              }
 586              foreach ($extraquestionfields as $field) {
 587                  if (property_exists($question, $field)) {
 588                      $options->$field = $question->$field;
 589                  }
 590              }
 591  
 592              $DB->{$function}($question_extension_table, $options);
 593          }
 594      }
 595  
 596      /**
 597       * Save the answers, with any extra data.
 598       *
 599       * Questions that use answers will call it from {@link save_question_options()}.
 600       * @param object $question  This holds the information from the editing form,
 601       *      it is not a standard question object.
 602       * @return object $result->error or $result->notice
 603       */
 604      public function save_question_answers($question) {
 605          global $DB;
 606  
 607          $context = $question->context;
 608          $oldanswers = $DB->get_records('question_answers',
 609                  array('question' => $question->id), 'id ASC');
 610  
 611          // We need separate arrays for answers and extra answer data, so no JOINS there.
 612          $extraanswerfields = $this->extra_answer_fields();
 613          $isextraanswerfields = is_array($extraanswerfields);
 614          $extraanswertable = '';
 615          $oldanswerextras = array();
 616          if ($isextraanswerfields) {
 617              $extraanswertable = array_shift($extraanswerfields);
 618              if (!empty($oldanswers)) {
 619                  $oldanswerextras = $DB->get_records_sql("SELECT * FROM {{$extraanswertable}} WHERE " .
 620                      'answerid IN (SELECT id FROM {question_answers} WHERE question = ' . $question->id . ')' );
 621              }
 622          }
 623  
 624          // Insert all the new answers.
 625          foreach ($question->answer as $key => $answerdata) {
 626              // Check for, and ignore, completely blank answer from the form.
 627              if ($this->is_answer_empty($question, $key)) {
 628                  continue;
 629              }
 630  
 631              // Update an existing answer if possible.
 632              $answer = array_shift($oldanswers);
 633              if (!$answer) {
 634                  $answer = new stdClass();
 635                  $answer->question = $question->id;
 636                  $answer->answer = '';
 637                  $answer->feedback = '';
 638                  $answer->id = $DB->insert_record('question_answers', $answer);
 639              }
 640  
 641              $answer = $this->fill_answer_fields($answer, $question, $key, $context);
 642              $DB->update_record('question_answers', $answer);
 643  
 644              if ($isextraanswerfields) {
 645                  // Check, if this answer contains some extra field data.
 646                  if ($this->is_extra_answer_fields_empty($question, $key)) {
 647                      continue;
 648                  }
 649  
 650                  $answerextra = array_shift($oldanswerextras);
 651                  if (!$answerextra) {
 652                      $answerextra = new stdClass();
 653                      $answerextra->answerid = $answer->id;
 654                      // Avoid looking for correct default for any possible DB field type
 655                      // by setting real values.
 656                      $answerextra = $this->fill_extra_answer_fields($answerextra, $question, $key, $context, $extraanswerfields);
 657                      $answerextra->id = $DB->insert_record($extraanswertable, $answerextra);
 658                  } else {
 659                      // Update answerid, as record may be reused from another answer.
 660                      $answerextra->answerid = $answer->id;
 661                      $answerextra = $this->fill_extra_answer_fields($answerextra, $question, $key, $context, $extraanswerfields);
 662                      $DB->update_record($extraanswertable, $answerextra);
 663                  }
 664              }
 665          }
 666  
 667          if ($isextraanswerfields) {
 668              // Delete any left over extra answer fields records.
 669              $oldanswerextraids = array();
 670              foreach ($oldanswerextras as $oldextra) {
 671                  $oldanswerextraids[] = $oldextra->id;
 672              }
 673              $DB->delete_records_list($extraanswertable, 'id', $oldanswerextraids);
 674          }
 675  
 676          // Delete any left over old answer records.
 677          $fs = get_file_storage();
 678          foreach ($oldanswers as $oldanswer) {
 679              $fs->delete_area_files($context->id, 'question', 'answerfeedback', $oldanswer->id);
 680              $DB->delete_records('question_answers', array('id' => $oldanswer->id));
 681          }
 682      }
 683  
 684      /**
 685       * Returns true is answer with the $key is empty in the question data and should not be saved in DB.
 686       *
 687       * The questions using question_answers table may want to overload this. Default code will work
 688       * for shortanswer and similar question types.
 689       * @param object $questiondata This holds the information from the question editing form or import.
 690       * @param int $key A key of the answer in question.
 691       * @return bool True if answer shouldn't be saved in DB.
 692       */
 693      protected function is_answer_empty($questiondata, $key) {
 694          return trim($questiondata->answer[$key]) == '' && $questiondata->fraction[$key] == 0 &&
 695                      html_is_blank($questiondata->feedback[$key]['text']);
 696      }
 697  
 698      /**
 699       * Return $answer, filling necessary fields for the question_answers table.
 700       *
 701       * The questions using question_answers table may want to overload this. Default code will work
 702       * for shortanswer and similar question types.
 703       * @param stdClass $answer Object to save data.
 704       * @param object $questiondata This holds the information from the question editing form or import.
 705       * @param int $key A key of the answer in question.
 706       * @param object $context needed for working with files.
 707       * @return $answer answer with filled data.
 708       */
 709      protected function fill_answer_fields($answer, $questiondata, $key, $context) {
 710          $answer->answer   = $questiondata->answer[$key];
 711          $answer->fraction = $questiondata->fraction[$key];
 712          $answer->feedback = $this->import_or_save_files($questiondata->feedback[$key],
 713                  $context, 'question', 'answerfeedback', $answer->id);
 714          $answer->feedbackformat = $questiondata->feedback[$key]['format'];
 715          return $answer;
 716      }
 717  
 718      /**
 719       * Returns true if extra answer fields for answer with the $key is empty
 720       * in the question data and should not be saved in DB.
 721       *
 722       * Questions where extra answer fields are optional will want to overload this.
 723       * @param object $questiondata This holds the information from the question editing form or import.
 724       * @param int $key A key of the answer in question.
 725       * @return bool True if extra answer data shouldn't be saved in DB.
 726       */
 727      protected function is_extra_answer_fields_empty($questiondata, $key) {
 728          // No extra answer data in base class.
 729          return true;
 730      }
 731  
 732      /**
 733       * Return $answerextra, filling necessary fields for the extra answer fields table.
 734       *
 735       * The questions may want to overload it to save files or do other data processing.
 736       * @param stdClass $answerextra Object to save data.
 737       * @param object $questiondata This holds the information from the question editing form or import.
 738       * @param int $key A key of the answer in question.
 739       * @param object $context needed for working with files.
 740       * @param array $extraanswerfields extra answer fields (without table name).
 741       * @return $answer answerextra with filled data.
 742       */
 743      protected function fill_extra_answer_fields($answerextra, $questiondata, $key, $context, $extraanswerfields) {
 744          foreach ($extraanswerfields as $field) {
 745              // The $questiondata->$field[$key] won't work in PHP, break it down to two strings of code.
 746              $fieldarray = $questiondata->$field;
 747              $answerextra->$field = $fieldarray[$key];
 748          }
 749          return $answerextra;
 750      }
 751  
 752      public function save_hints($formdata, $withparts = false) {
 753          global $DB;
 754          $context = $formdata->context;
 755  
 756          $oldhints = $DB->get_records('question_hints',
 757                  array('questionid' => $formdata->id), 'id ASC');
 758  
 759  
 760          $numhints = $this->count_hints_on_form($formdata, $withparts);
 761  
 762          for ($i = 0; $i < $numhints; $i += 1) {
 763              if (html_is_blank($formdata->hint[$i]['text'])) {
 764                  $formdata->hint[$i]['text'] = '';
 765              }
 766  
 767              if ($withparts) {
 768                  $clearwrong = !empty($formdata->hintclearwrong[$i]);
 769                  $shownumcorrect = !empty($formdata->hintshownumcorrect[$i]);
 770              }
 771  
 772              if ($this->is_hint_empty_in_form_data($formdata, $i, $withparts)) {
 773                  continue;
 774              }
 775  
 776              // Update an existing hint if possible.
 777              $hint = array_shift($oldhints);
 778              if (!$hint) {
 779                  $hint = new stdClass();
 780                  $hint->questionid = $formdata->id;
 781                  $hint->hint = '';
 782                  $hint->id = $DB->insert_record('question_hints', $hint);
 783              }
 784  
 785              $hint->hint = $this->import_or_save_files($formdata->hint[$i],
 786                      $context, 'question', 'hint', $hint->id);
 787              $hint->hintformat = $formdata->hint[$i]['format'];
 788              if ($withparts) {
 789                  $hint->clearwrong = $clearwrong;
 790                  $hint->shownumcorrect = $shownumcorrect;
 791              }
 792              $hint->options = $this->save_hint_options($formdata, $i, $withparts);
 793              $DB->update_record('question_hints', $hint);
 794          }
 795  
 796          // Delete any remaining old hints.
 797          $fs = get_file_storage();
 798          foreach ($oldhints as $oldhint) {
 799              $fs->delete_area_files($context->id, 'question', 'hint', $oldhint->id);
 800              $DB->delete_records('question_hints', array('id' => $oldhint->id));
 801          }
 802      }
 803  
 804      /**
 805       * Count number of hints on the form.
 806       * Overload if you use custom hint controls.
 807       * @param object $formdata the data from the form.
 808       * @param bool $withparts whether to take into account clearwrong and shownumcorrect options.
 809       * @return int count of hints on the form.
 810       */
 811      protected function count_hints_on_form($formdata, $withparts) {
 812          if (!empty($formdata->hint)) {
 813              $numhints = max(array_keys($formdata->hint)) + 1;
 814          } else {
 815              $numhints = 0;
 816          }
 817  
 818          if ($withparts) {
 819              if (!empty($formdata->hintclearwrong)) {
 820                  $numclears = max(array_keys($formdata->hintclearwrong)) + 1;
 821              } else {
 822                  $numclears = 0;
 823              }
 824              if (!empty($formdata->hintshownumcorrect)) {
 825                  $numshows = max(array_keys($formdata->hintshownumcorrect)) + 1;
 826              } else {
 827                  $numshows = 0;
 828              }
 829              $numhints = max($numhints, $numclears, $numshows);
 830          }
 831          return $numhints;
 832      }
 833  
 834      /**
 835       * Determine if the hint with specified number is not empty and should be saved.
 836       * Overload if you use custom hint controls.
 837       * @param object $formdata the data from the form.
 838       * @param int $number number of hint under question.
 839       * @param bool $withparts whether to take into account clearwrong and shownumcorrect options.
 840       * @return bool is this particular hint data empty.
 841       */
 842      protected function is_hint_empty_in_form_data($formdata, $number, $withparts) {
 843          if ($withparts) {
 844              return empty($formdata->hint[$number]['text']) && empty($formdata->hintclearwrong[$number]) &&
 845                      empty($formdata->hintshownumcorrect[$number]);
 846          } else {
 847              return  empty($formdata->hint[$number]['text']);
 848          }
 849      }
 850  
 851      /**
 852       * Save additional question type data into the hint optional field.
 853       * Overload if you use custom hint information.
 854       * @param object $formdata the data from the form.
 855       * @param int $number number of hint to get options from.
 856       * @param bool $withparts whether question have parts.
 857       * @return string value to save into the options field of question_hints table.
 858       */
 859      protected function save_hint_options($formdata, $number, $withparts) {
 860          return null;    // By default, options field is unused.
 861      }
 862  
 863      /**
 864       * Can be used to {@link save_question_options()} to transfer the combined
 865       * feedback fields from $formdata to $options.
 866       * @param object $options the $question->options object being built.
 867       * @param object $formdata the data from the form.
 868       * @param object $context the context the quetsion is being saved into.
 869       * @param bool $withparts whether $options->shownumcorrect should be set.
 870       */
 871      protected function save_combined_feedback_helper($options, $formdata,
 872              $context, $withparts = false) {
 873          $options->correctfeedback = $this->import_or_save_files($formdata->correctfeedback,
 874                  $context, 'question', 'correctfeedback', $formdata->id);
 875          $options->correctfeedbackformat = $formdata->correctfeedback['format'];
 876  
 877          $options->partiallycorrectfeedback = $this->import_or_save_files(
 878                  $formdata->partiallycorrectfeedback,
 879                  $context, 'question', 'partiallycorrectfeedback', $formdata->id);
 880          $options->partiallycorrectfeedbackformat = $formdata->partiallycorrectfeedback['format'];
 881  
 882          $options->incorrectfeedback = $this->import_or_save_files($formdata->incorrectfeedback,
 883                  $context, 'question', 'incorrectfeedback', $formdata->id);
 884          $options->incorrectfeedbackformat = $formdata->incorrectfeedback['format'];
 885  
 886          if ($withparts) {
 887              $options->shownumcorrect = !empty($formdata->shownumcorrect);
 888          }
 889  
 890          return $options;
 891      }
 892  
 893      /**
 894       * Loads the question type specific options for the question.
 895       *
 896       * This function loads any question type specific options for the
 897       * question from the database into the question object. This information
 898       * is placed in the $question->options field. A question type is
 899       * free, however, to decide on a internal structure of the options field.
 900       * @return bool            Indicates success or failure.
 901       * @param object $question The question object for the question. This object
 902       *                         should be updated to include the question type
 903       *                         specific information (it is passed by reference).
 904       */
 905      public function get_question_options($question) {
 906          global $DB, $OUTPUT;
 907  
 908          if (!isset($question->options)) {
 909              $question->options = new stdClass();
 910          }
 911  
 912          $extraquestionfields = $this->extra_question_fields();
 913          if (is_array($extraquestionfields)) {
 914              $question_extension_table = array_shift($extraquestionfields);
 915              $extra_data = $DB->get_record($question_extension_table,
 916                      array($this->questionid_column_name() => $question->id),
 917                      implode(', ', $extraquestionfields));
 918              if ($extra_data) {
 919                  foreach ($extraquestionfields as $field) {
 920                      $question->options->$field = $extra_data->$field;
 921                  }
 922              } else {
 923                  echo $OUTPUT->notification('Failed to load question options from the table ' .
 924                          $question_extension_table . ' for questionid ' . $question->id);
 925                  return false;
 926              }
 927          }
 928  
 929          $extraanswerfields = $this->extra_answer_fields();
 930          if (is_array($extraanswerfields)) {
 931              $answerextensiontable = array_shift($extraanswerfields);
 932              // Use LEFT JOIN in case not every answer has extra data.
 933              $question->options->answers = $DB->get_records_sql("
 934                      SELECT qa.*, qax." . implode(', qax.', $extraanswerfields) . '
 935                      FROM {question_answers} qa ' . "
 936                      LEFT JOIN {{$answerextensiontable}} qax ON qa.id = qax.answerid
 937                      WHERE qa.question = ?
 938                      ORDER BY qa.id", array($question->id));
 939              if (!$question->options->answers) {
 940                  echo $OUTPUT->notification('Failed to load question answers from the table ' .
 941                          $answerextensiontable . 'for questionid ' . $question->id);
 942                  return false;
 943              }
 944          } else {
 945              // Don't check for success or failure because some question types do
 946              // not use the answers table.
 947              $question->options->answers = $DB->get_records('question_answers',
 948                      array('question' => $question->id), 'id ASC');
 949          }
 950  
 951          $question->hints = $DB->get_records('question_hints',
 952                  array('questionid' => $question->id), 'id ASC');
 953  
 954          return true;
 955      }
 956  
 957      /**
 958       * Create an appropriate question_definition for the question of this type
 959       * using data loaded from the database.
 960       * @param object $questiondata the question data loaded from the database.
 961       * @return question_definition the corresponding question_definition.
 962       */
 963      public function make_question($questiondata) {
 964          $question = $this->make_question_instance($questiondata);
 965          $this->initialise_question_instance($question, $questiondata);
 966          return $question;
 967      }
 968  
 969      /**
 970       * Create an appropriate question_definition for the question of this type
 971       * using data loaded from the database.
 972       * @param object $questiondata the question data loaded from the database.
 973       * @return question_definition an instance of the appropriate question_definition subclass.
 974       *      Still needs to be initialised.
 975       */
 976      protected function make_question_instance($questiondata) {
 977          question_bank::load_question_definition_classes($this->name());
 978          $class = 'qtype_' . $this->name() . '_question';
 979          return new $class();
 980      }
 981  
 982      /**
 983       * Initialise the common question_definition fields.
 984       * @param question_definition $question the question_definition we are creating.
 985       * @param object $questiondata the question data loaded from the database.
 986       */
 987      protected function initialise_question_instance(question_definition $question, $questiondata) {
 988          $question->id = $questiondata->id;
 989          $question->category = $questiondata->category;
 990          $question->contextid = $questiondata->contextid;
 991          $question->parent = $questiondata->parent;
 992          $question->qtype = $this;
 993          $question->name = $questiondata->name;
 994          $question->questiontext = $questiondata->questiontext;
 995          $question->questiontextformat = $questiondata->questiontextformat;
 996          $question->generalfeedback = $questiondata->generalfeedback;
 997          $question->generalfeedbackformat = $questiondata->generalfeedbackformat;
 998          $question->defaultmark = $questiondata->defaultmark + 0;
 999          $question->length = $questiondata->length;
1000          $question->penalty = $questiondata->penalty;
1001          $question->stamp = $questiondata->stamp;
1002          $question->timecreated = $questiondata->timecreated;
1003          $question->timemodified = $questiondata->timemodified;
1004          $question->createdby = $questiondata->createdby;
1005          $question->modifiedby = $questiondata->modifiedby;
1006  
1007          $this->initialise_core_question_metadata($question, $questiondata);
1008  
1009          // Fill extra question fields values.
1010          $extraquestionfields = $this->extra_question_fields();
1011          if (is_array($extraquestionfields)) {
1012              // Omit table name.
1013              array_shift($extraquestionfields);
1014              foreach ($extraquestionfields as $field) {
1015                  $question->$field = $questiondata->options->$field;
1016              }
1017          }
1018  
1019          $this->initialise_question_hints($question, $questiondata);
1020  
1021          // Add the custom fields.
1022          $this->initialise_custom_fields($question, $questiondata);
1023      }
1024  
1025      /**
1026       * Initialise the question metadata.
1027       *
1028       * @param question_definition $question the question_definition we are creating.
1029       * @param object $questiondata the question data loaded from the database.
1030       */
1031      protected function initialise_core_question_metadata(question_definition $question, $questiondata) {
1032          $fields =
1033              [
1034                  'status',
1035                  'versionid',
1036                  'version',
1037                  'questionbankentryid',
1038                  'idnumber',
1039              ];
1040  
1041          foreach ($fields as $field) {
1042              if (isset($questiondata->{$field})) {
1043                  $question->{$field} = $questiondata->{$field};
1044              }
1045          }
1046      }
1047  
1048      /**
1049       * Initialise question_definition::hints field.
1050       * @param question_definition $question the question_definition we are creating.
1051       * @param object $questiondata the question data loaded from the database.
1052       */
1053      protected function initialise_question_hints(question_definition $question, $questiondata) {
1054          if (empty($questiondata->hints)) {
1055              return;
1056          }
1057          foreach ($questiondata->hints as $hint) {
1058              $question->hints[] = $this->make_hint($hint);
1059          }
1060      }
1061  
1062      /**
1063       * Create a question_hint, or an appropriate subclass for this question,
1064       * from a row loaded from the database.
1065       * @param object $hint the DB row from the question hints table.
1066       * @return question_hint
1067       */
1068      protected function make_hint($hint) {
1069          return question_hint::load_from_record($hint);
1070      }
1071  
1072      /**
1073       * Initialise question custom fields.
1074       * @param question_definition $question the question_definition we are creating.
1075       * @param object $questiondata the question data loaded from the database.
1076       */
1077      protected function initialise_custom_fields(question_definition $question, $questiondata) {
1078          if (!empty($questiondata->customfields)) {
1079               $question->customfields = $questiondata->customfields;
1080          }
1081      }
1082  
1083      /**
1084       * Initialise the combined feedback fields.
1085       * @param question_definition $question the question_definition we are creating.
1086       * @param object $questiondata the question data loaded from the database.
1087       * @param bool $withparts whether to set the shownumcorrect field.
1088       */
1089      protected function initialise_combined_feedback(question_definition $question,
1090              $questiondata, $withparts = false) {
1091          $question->correctfeedback = $questiondata->options->correctfeedback;
1092          $question->correctfeedbackformat = $questiondata->options->correctfeedbackformat;
1093          $question->partiallycorrectfeedback = $questiondata->options->partiallycorrectfeedback;
1094          $question->partiallycorrectfeedbackformat =
1095                  $questiondata->options->partiallycorrectfeedbackformat;
1096          $question->incorrectfeedback = $questiondata->options->incorrectfeedback;
1097          $question->incorrectfeedbackformat = $questiondata->options->incorrectfeedbackformat;
1098          if ($withparts) {
1099              $question->shownumcorrect = $questiondata->options->shownumcorrect;
1100          }
1101      }
1102  
1103      /**
1104       * Initialise question_definition::answers field.
1105       * @param question_definition $question the question_definition we are creating.
1106       * @param object $questiondata the question data loaded from the database.
1107       * @param bool $forceplaintextanswers most qtypes assume that answers are
1108       *      FORMAT_PLAIN, and dont use the answerformat DB column (it contains
1109       *      the default 0 = FORMAT_MOODLE). Therefore, by default this method
1110       *      ingores answerformat. Pass false here to use answerformat. For example
1111       *      multichoice does this.
1112       */
1113      protected function initialise_question_answers(question_definition $question,
1114              $questiondata, $forceplaintextanswers = true) {
1115          $question->answers = array();
1116          if (empty($questiondata->options->answers)) {
1117              return;
1118          }
1119          foreach ($questiondata->options->answers as $a) {
1120              $question->answers[$a->id] = $this->make_answer($a);
1121              if (!$forceplaintextanswers) {
1122                  $question->answers[$a->id]->answerformat = $a->answerformat;
1123              }
1124          }
1125      }
1126  
1127      /**
1128       * Create a question_answer, or an appropriate subclass for this question,
1129       * from a row loaded from the database.
1130       * @param object $answer the DB row from the question_answers table plus extra answer fields.
1131       * @return question_answer
1132       */
1133      protected function make_answer($answer) {
1134          return new question_answer($answer->id, $answer->answer,
1135                      $answer->fraction, $answer->feedback, $answer->feedbackformat);
1136      }
1137  
1138      /**
1139       * Deletes the question-type specific data when a question is deleted.
1140       * @param int $question the question being deleted.
1141       * @param int $contextid the context this quesiotn belongs to.
1142       */
1143      public function delete_question($questionid, $contextid) {
1144          global $DB;
1145  
1146          $this->delete_files($questionid, $contextid);
1147  
1148          $extraquestionfields = $this->extra_question_fields();
1149          if (is_array($extraquestionfields)) {
1150              $question_extension_table = array_shift($extraquestionfields);
1151              $DB->delete_records($question_extension_table,
1152                      array($this->questionid_column_name() => $questionid));
1153          }
1154  
1155          $extraanswerfields = $this->extra_answer_fields();
1156          if (is_array($extraanswerfields)) {
1157              $answer_extension_table = array_shift($extraanswerfields);
1158              $DB->delete_records_select($answer_extension_table,
1159                      'answerid IN (SELECT qa.id FROM {question_answers} qa WHERE qa.question = ?)',
1160                      array($questionid));
1161          }
1162  
1163          $DB->delete_records('question_answers', array('question' => $questionid));
1164  
1165          $DB->delete_records('question_hints', array('questionid' => $questionid));
1166      }
1167  
1168      /**
1169       * Returns the number of question numbers which are used by the question
1170       *
1171       * This function returns the number of question numbers to be assigned
1172       * to the question. Most question types will have length one; they will be
1173       * assigned one number. The 'description' type, however does not use up a
1174       * number and so has a length of zero. Other question types may wish to
1175       * handle a bundle of questions and hence return a number greater than one.
1176       * @return int         The number of question numbers which should be
1177       *                         assigned to the question.
1178       * @param object $question The question whose length is to be determined.
1179       *                         Question type specific information is included.
1180       */
1181      public function actual_number_of_questions($question) {
1182          // By default, each question is given one number.
1183          return 1;
1184      }
1185  
1186      /**
1187       * Calculate the score a monkey would get on a question by clicking randomly.
1188       *
1189       * Some question types have significant non-zero average expected score
1190       * of the response is just selected randomly. For example 50% for a
1191       * true-false question. It is useful to know what this is. For example
1192       * it gets shown in the quiz statistics report.
1193       *
1194       * For almost any open-ended question type (E.g. shortanswer or numerical)
1195       * this should be 0.
1196       *
1197       * For selective response question types (e.g. multiple choice), you can probably compute this.
1198       *
1199       * For particularly complicated question types the may be impossible or very
1200       * difficult to compute. In this case return null. (Or, if the expected score
1201       * is very tiny even though the exact value is unknown, it may appropriate
1202       * to return 0.)
1203       *
1204       * @param stdClass $questiondata data defining a question, as returned by
1205       *      question_bank::load_question_data().
1206       * @return number|null either a fraction estimating what the student would
1207       *      score by guessing, or null, if it is not possible to estimate.
1208       */
1209      public function get_random_guess_score($questiondata) {
1210          return 0;
1211      }
1212  
1213      /**
1214       * Whether or not to break down question stats and response analysis, for a question defined by $questiondata.
1215       *
1216       * @param object $questiondata The full question definition data.
1217       * @return bool
1218       */
1219      public function break_down_stats_and_response_analysis_by_variant($questiondata) {
1220          return true;
1221      }
1222  
1223      /**
1224       * This method should return all the possible types of response that are
1225       * recognised for this question.
1226       *
1227       * The question is modelled as comprising one or more subparts. For each
1228       * subpart, there are one or more classes that that students response
1229       * might fall into, each of those classes earning a certain score.
1230       *
1231       * For example, in a shortanswer question, there is only one subpart, the
1232       * text entry field. The response the student gave will be classified according
1233       * to which of the possible $question->options->answers it matches.
1234       *
1235       * For the matching question type, there will be one subpart for each
1236       * question stem, and for each stem, each of the possible choices is a class
1237       * of student's response.
1238       *
1239       * A response is an object with two fields, ->responseclass is a string
1240       * presentation of that response, and ->fraction, the credit for a response
1241       * in that class.
1242       *
1243       * Array keys have no specific meaning, but must be unique, and must be
1244       * the same if this function is called repeatedly.
1245       *
1246       * @param object $question the question definition data.
1247       * @return array keys are subquestionid, values are arrays of possible
1248       *      responses to that subquestion.
1249       */
1250      public function get_possible_responses($questiondata) {
1251          return array();
1252      }
1253  
1254      /**
1255       * Utility method used by {@link qtype_renderer::head_code()}. It looks
1256       * for any of the files script.js or script.php that exist in the plugin
1257       * folder and ensures they get included.
1258       */
1259      public function find_standard_scripts() {
1260          global $PAGE;
1261  
1262          $plugindir = $this->plugin_dir();
1263          $plugindirrel = 'question/type/' . $this->name();
1264  
1265          if (file_exists($plugindir . '/script.js')) {
1266              $PAGE->requires->js('/' . $plugindirrel . '/script.js');
1267          }
1268          if (file_exists($plugindir . '/script.php')) {
1269              $PAGE->requires->js('/' . $plugindirrel . '/script.php');
1270          }
1271      }
1272  
1273      /**
1274       * Returns true if the editing wizard is finished, false otherwise.
1275       *
1276       * The default implementation returns true, which is suitable for all question-
1277       * types that only use one editing form. This function is used in
1278       * question.php to decide whether we can regrade any states of the edited
1279       * question and redirect to edit.php.
1280       *
1281       * The dataset dependent question-type, which is extended by the calculated
1282       * question-type, overwrites this method because it uses multiple pages (i.e.
1283       * a wizard) to set up the question and associated datasets.
1284       *
1285       * @param object $form  The data submitted by the previous page.
1286       *
1287       * @return bool      Whether the wizard's last page was submitted or not.
1288       */
1289      public function finished_edit_wizard($form) {
1290          // In the default case there is only one edit page.
1291          return true;
1292      }
1293  
1294      // IMPORT/EXPORT FUNCTIONS --------------------------------- .
1295  
1296      /*
1297       * Imports question from the Moodle XML format
1298       *
1299       * Imports question using information from extra_question_fields function
1300       * If some of you fields contains id's you'll need to reimplement this
1301       */
1302      public function import_from_xml($data, $question, qformat_xml $format, $extra=null) {
1303          $question_type = $data['@']['type'];
1304          if ($question_type != $this->name()) {
1305              return false;
1306          }
1307  
1308          $extraquestionfields = $this->extra_question_fields();
1309          if (!is_array($extraquestionfields)) {
1310              return false;
1311          }
1312  
1313          // Omit table name.
1314          array_shift($extraquestionfields);
1315          $qo = $format->import_headers($data);
1316          $qo->qtype = $question_type;
1317  
1318          foreach ($extraquestionfields as $field) {
1319              $qo->$field = $format->getpath($data, array('#', $field, 0, '#'), '');
1320          }
1321  
1322          // Run through the answers.
1323          $answers = $data['#']['answer'];
1324          $a_count = 0;
1325          $extraanswersfields = $this->extra_answer_fields();
1326          if (is_array($extraanswersfields)) {
1327              array_shift($extraanswersfields);
1328          }
1329          foreach ($answers as $answer) {
1330              $ans = $format->import_answer($answer);
1331              if (!$this->has_html_answers()) {
1332                  $qo->answer[$a_count] = $ans->answer['text'];
1333              } else {
1334                  $qo->answer[$a_count] = $ans->answer;
1335              }
1336              $qo->fraction[$a_count] = $ans->fraction;
1337              $qo->feedback[$a_count] = $ans->feedback;
1338              if (is_array($extraanswersfields)) {
1339                  foreach ($extraanswersfields as $field) {
1340                      $qo->{$field}[$a_count] =
1341                          $format->getpath($answer, array('#', $field, 0, '#'), '');
1342                  }
1343              }
1344              ++$a_count;
1345          }
1346          return $qo;
1347      }
1348  
1349      /*
1350       * Export question to the Moodle XML format
1351       *
1352       * Export question using information from extra_question_fields function
1353       * If some of you fields contains id's you'll need to reimplement this
1354       */
1355      public function export_to_xml($question, qformat_xml $format, $extra=null) {
1356          $extraquestionfields = $this->extra_question_fields();
1357          if (!is_array($extraquestionfields)) {
1358              return false;
1359          }
1360  
1361          // Omit table name.
1362          array_shift($extraquestionfields);
1363          $expout='';
1364          foreach ($extraquestionfields as $field) {
1365              $exportedvalue = $format->xml_escape($question->options->$field);
1366              $expout .= "    <{$field}>{$exportedvalue}</{$field}>\n";
1367          }
1368  
1369          $extraanswersfields = $this->extra_answer_fields();
1370          if (is_array($extraanswersfields)) {
1371              array_shift($extraanswersfields);
1372          }
1373          foreach ($question->options->answers as $answer) {
1374              $extra = '';
1375              if (is_array($extraanswersfields)) {
1376                  foreach ($extraanswersfields as $field) {
1377                      $exportedvalue = $format->xml_escape($answer->$field);
1378                      $extra .= "      <{$field}>{$exportedvalue}</{$field}>\n";
1379                  }
1380              }
1381  
1382              $expout .= $format->write_answer($answer, $extra);
1383          }
1384          return $expout;
1385      }
1386  
1387      /**
1388       * Abstract function implemented by each question type. It runs all the code
1389       * required to set up and save a question of any type for testing purposes.
1390       * Alternate DB table prefix may be used to facilitate data deletion.
1391       */
1392      public function generate_test($name, $courseid=null) {
1393          $form = new stdClass();
1394          $form->name = $name;
1395          $form->questiontextformat = 1;
1396          $form->questiontext = 'test question, generated by script';
1397          $form->defaultmark = 1;
1398          $form->penalty = 0.3333333;
1399          $form->status = \core_question\local\bank\question_version_status::QUESTION_STATUS_READY;
1400          $form->generalfeedback = "Well done";
1401  
1402          $context = context_course::instance($courseid);
1403          $newcategory = question_make_default_categories(array($context));
1404          $form->category = $newcategory->id . ',1';
1405  
1406          $question = new stdClass();
1407          $question->courseid = $courseid;
1408          $question->qtype = $this->name();
1409          return array($form, $question);
1410      }
1411  
1412      /**
1413       * Get question context by category id
1414       * @param int $category
1415       * @return object $context
1416       */
1417      protected function get_context_by_category_id($category) {
1418          global $DB;
1419          $contextid = $DB->get_field('question_categories', 'contextid', array('id'=>$category));
1420          $context = context::instance_by_id($contextid, IGNORE_MISSING);
1421          return $context;
1422      }
1423  
1424      /**
1425       * Save the file belonging to one text field.
1426       *
1427       * @param array $field the data from the form (or from import). This will
1428       *      normally have come from the formslib editor element, so it will be an
1429       *      array with keys 'text', 'format' and 'itemid'. However, when we are
1430       *      importing, it will be an array with keys 'text', 'format' and 'files'
1431       * @param object $context the context the question is in.
1432       * @param string $component indentifies the file area question.
1433       * @param string $filearea indentifies the file area questiontext,
1434       *      generalfeedback, answerfeedback, etc.
1435       * @param int $itemid identifies the file area.
1436       *
1437       * @return string the text for this field, after files have been processed.
1438       */
1439      protected function import_or_save_files($field, $context, $component, $filearea, $itemid) {
1440          if (!empty($field['itemid'])) {
1441              // This is the normal case. We are safing the questions editing form.
1442              return file_save_draft_area_files($field['itemid'], $context->id, $component,
1443                      $filearea, $itemid, $this->fileoptions, trim($field['text']));
1444  
1445          } else if (!empty($field['files'])) {
1446              // This is the case when we are doing an import.
1447              foreach ($field['files'] as $file) {
1448                  $this->import_file($context, $component,  $filearea, $itemid, $file);
1449              }
1450          }
1451          return trim($field['text']);
1452      }
1453  
1454      /**
1455       * Move all the files belonging to this question from one context to another.
1456       * @param int $questionid the question being moved.
1457       * @param int $oldcontextid the context it is moving from.
1458       * @param int $newcontextid the context it is moving to.
1459       */
1460      public function move_files($questionid, $oldcontextid, $newcontextid) {
1461          $fs = get_file_storage();
1462          $fs->move_area_files_to_new_context($oldcontextid,
1463                  $newcontextid, 'question', 'questiontext', $questionid);
1464          $fs->move_area_files_to_new_context($oldcontextid,
1465                  $newcontextid, 'question', 'generalfeedback', $questionid);
1466      }
1467  
1468      /**
1469       * Move all the files belonging to this question's answers when the question
1470       * is moved from one context to another.
1471       * @param int $questionid the question being moved.
1472       * @param int $oldcontextid the context it is moving from.
1473       * @param int $newcontextid the context it is moving to.
1474       * @param bool $answerstoo whether there is an 'answer' question area,
1475       *      as well as an 'answerfeedback' one. Default false.
1476       */
1477      protected function move_files_in_answers($questionid, $oldcontextid,
1478              $newcontextid, $answerstoo = false) {
1479          global $DB;
1480          $fs = get_file_storage();
1481  
1482          $answerids = $DB->get_records_menu('question_answers',
1483                  array('question' => $questionid), 'id', 'id,1');
1484          foreach ($answerids as $answerid => $notused) {
1485              if ($answerstoo) {
1486                  $fs->move_area_files_to_new_context($oldcontextid,
1487                          $newcontextid, 'question', 'answer', $answerid);
1488              }
1489              $fs->move_area_files_to_new_context($oldcontextid,
1490                      $newcontextid, 'question', 'answerfeedback', $answerid);
1491          }
1492      }
1493  
1494      /**
1495       * Move all the files belonging to this question's hints when the question
1496       * is moved from one context to another.
1497       * @param int $questionid the question being moved.
1498       * @param int $oldcontextid the context it is moving from.
1499       * @param int $newcontextid the context it is moving to.
1500       * @param bool $answerstoo whether there is an 'answer' question area,
1501       *      as well as an 'answerfeedback' one. Default false.
1502       */
1503      protected function move_files_in_hints($questionid, $oldcontextid, $newcontextid) {
1504          global $DB;
1505          $fs = get_file_storage();
1506  
1507          $hintids = $DB->get_records_menu('question_hints',
1508                  array('questionid' => $questionid), 'id', 'id,1');
1509          foreach ($hintids as $hintid => $notused) {
1510              $fs->move_area_files_to_new_context($oldcontextid,
1511                      $newcontextid, 'question', 'hint', $hintid);
1512          }
1513      }
1514  
1515      /**
1516       * Move all the files belonging to this question's answers when the question
1517       * is moved from one context to another.
1518       * @param int $questionid the question being moved.
1519       * @param int $oldcontextid the context it is moving from.
1520       * @param int $newcontextid the context it is moving to.
1521       * @param bool $answerstoo whether there is an 'answer' question area,
1522       *      as well as an 'answerfeedback' one. Default false.
1523       */
1524      protected function move_files_in_combined_feedback($questionid, $oldcontextid,
1525              $newcontextid) {
1526          global $DB;
1527          $fs = get_file_storage();
1528  
1529          $fs->move_area_files_to_new_context($oldcontextid,
1530                  $newcontextid, 'question', 'correctfeedback', $questionid);
1531          $fs->move_area_files_to_new_context($oldcontextid,
1532                  $newcontextid, 'question', 'partiallycorrectfeedback', $questionid);
1533          $fs->move_area_files_to_new_context($oldcontextid,
1534                  $newcontextid, 'question', 'incorrectfeedback', $questionid);
1535      }
1536  
1537      /**
1538       * Delete all the files belonging to this question.
1539       * @param int $questionid the question being deleted.
1540       * @param int $contextid the context the question is in.
1541       */
1542      protected function delete_files($questionid, $contextid) {
1543          $fs = get_file_storage();
1544          $fs->delete_area_files($contextid, 'question', 'questiontext', $questionid);
1545          $fs->delete_area_files($contextid, 'question', 'generalfeedback', $questionid);
1546      }
1547  
1548      /**
1549       * Delete all the files belonging to this question's answers.
1550       * @param int $questionid the question being deleted.
1551       * @param int $contextid the context the question is in.
1552       * @param bool $answerstoo whether there is an 'answer' question area,
1553       *      as well as an 'answerfeedback' one. Default false.
1554       */
1555      protected function delete_files_in_answers($questionid, $contextid, $answerstoo = false) {
1556          global $DB;
1557          $fs = get_file_storage();
1558  
1559          $answerids = $DB->get_records_menu('question_answers',
1560                  array('question' => $questionid), 'id', 'id,1');
1561          foreach ($answerids as $answerid => $notused) {
1562              if ($answerstoo) {
1563                  $fs->delete_area_files($contextid, 'question', 'answer', $answerid);
1564              }
1565              $fs->delete_area_files($contextid, 'question', 'answerfeedback', $answerid);
1566          }
1567      }
1568  
1569      /**
1570       * Delete all the files belonging to this question's hints.
1571       * @param int $questionid the question being deleted.
1572       * @param int $contextid the context the question is in.
1573       */
1574      protected function delete_files_in_hints($questionid, $contextid) {
1575          global $DB;
1576          $fs = get_file_storage();
1577  
1578          $hintids = $DB->get_records_menu('question_hints',
1579                  array('questionid' => $questionid), 'id', 'id,1');
1580          foreach ($hintids as $hintid => $notused) {
1581              $fs->delete_area_files($contextid, 'question', 'hint', $hintid);
1582          }
1583      }
1584  
1585      /**
1586       * Delete all the files belonging to this question's answers.
1587       * @param int $questionid the question being deleted.
1588       * @param int $contextid the context the question is in.
1589       * @param bool $answerstoo whether there is an 'answer' question area,
1590       *      as well as an 'answerfeedback' one. Default false.
1591       */
1592      protected function delete_files_in_combined_feedback($questionid, $contextid) {
1593          global $DB;
1594          $fs = get_file_storage();
1595  
1596          $fs->delete_area_files($contextid,
1597                  'question', 'correctfeedback', $questionid);
1598          $fs->delete_area_files($contextid,
1599                  'question', 'partiallycorrectfeedback', $questionid);
1600          $fs->delete_area_files($contextid,
1601                  'question', 'incorrectfeedback', $questionid);
1602      }
1603  
1604      public function import_file($context, $component, $filearea, $itemid, $file) {
1605          $fs = get_file_storage();
1606          $record = new stdClass();
1607          if (is_object($context)) {
1608              $record->contextid = $context->id;
1609          } else {
1610              $record->contextid = $context;
1611          }
1612          $record->component = $component;
1613          $record->filearea  = $filearea;
1614          $record->itemid    = $itemid;
1615          $record->filename  = $file->name;
1616          $record->filepath  = '/';
1617          return $fs->create_file_from_string($record, $this->decode_file($file));
1618      }
1619  
1620      protected function decode_file($file) {
1621          switch ($file->encoding) {
1622              case 'base64':
1623              default:
1624                  return base64_decode($file->content);
1625          }
1626      }
1627  }
1628  
1629  
1630  /**
1631   * This class is used in the return value from
1632   * {@link question_type::get_possible_responses()}.
1633   *
1634   * @copyright  2010 The Open University
1635   * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
1636   */
1637  class question_possible_response {
1638      /**
1639       * @var string the classification of this response the student gave to this
1640       * part of the question. Must match one of the responseclasses returned by
1641       * {@link question_type::get_possible_responses()}.
1642       */
1643      public $responseclass;
1644  
1645      /** @var string the (partial) credit awarded for this responses. */
1646      public $fraction;
1647  
1648      /**
1649       * Constructor, just an easy way to set the fields.
1650       * @param string $responseclassid see the field descriptions above.
1651       * @param string $response see the field descriptions above.
1652       * @param number $fraction see the field descriptions above.
1653       */
1654      public function __construct($responseclass, $fraction) {
1655          $this->responseclass = $responseclass;
1656          $this->fraction = $fraction;
1657      }
1658  
1659      public static function no_response() {
1660          return new question_possible_response(get_string('noresponse', 'question'), 0);
1661      }
1662  }