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Developer Documentation
- Bug fixes for general core bugs in 3.11.x will end 14 Nov 2022 (12 months plus 6 months extension).
- Bug fixes for security issues in 3.11.x will end 13 Nov 2023 (18 months plus 12 months extension).
- PHP version: minimum PHP 7.3.0 Note: minimum PHP version has increased since Moodle 3.10. PHP 7.4.x is supported too.
/question/engine/ -> datalib.php (source)
Differences Between: [Versions 311 and 400] [Versions 311 and 401] [Versions 311 and 402] [Versions 311 and 403]
1 <?php 2 // This file is part of Moodle - http://moodle.org/ 3 // 4 // Moodle is free software: you can redistribute it and/or modify 5 // it under the terms of the GNU General Public License as published by 6 // the Free Software Foundation, either version 3 of the License, or 7 // (at your option) any later version. 8 // 9 // Moodle is distributed in the hope that it will be useful, 10 // but WITHOUT ANY WARRANTY; without even the implied warranty of 11 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 12 // GNU General Public License for more details. 13 // 14 // You should have received a copy of the GNU General Public License 15 // along with Moodle. If not, see <http://www.gnu.org/licenses/>. 16 17 /** 18 * Code for loading and saving question attempts to and from the database. 19 * 20 * Note that many of the methods of this class should be considered private to 21 * the question engine. They should be accessed through the 22 * {@link question_engine} class. For example, you should call 23 * {@link question_engine::save_questions_usage_by_activity()} rather than 24 * {@link question_engine_data_mapper::insert_questions_usage_by_activity()}. 25 * The exception to this is some of the reporting methods, like 26 * {@link question_engine_data_mapper::load_attempts_at_question()}. 27 * 28 * A note for future reference. This code is pretty efficient but there are some 29 * potential optimisations that could be contemplated, at the cost of making the 30 * code more complex: 31 * 32 * 1. (This is probably not worth doing.) In the unit-of-work save method, we 33 * could get all the ids for steps due to be deleted or modified, 34 * and delete all the question_attempt_step_data for all of those steps in one 35 * query. That would save one DB query for each ->stepsupdated. However that number 36 * is 0 except when re-grading, and when regrading, there are many more inserts 37 * into question_attempt_step_data than deletes, so it is really hardly worth it. 38 * 39 * @package core_question 40 * @copyright 2009 The Open University 41 * @license http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later 42 */ 43 44 45 defined('MOODLE_INTERNAL') || die(); 46 47 48 /** 49 * This class controls the loading and saving of question engine data to and from 50 * the database. 51 * 52 * @copyright 2009 The Open University 53 * @license http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later 54 */ 55 class question_engine_data_mapper { 56 /** 57 * @var moodle_database normally points to global $DB, but I prefer not to 58 * use globals if I can help it. 59 */ 60 protected $db; 61 62 /** 63 * @param moodle_database $db a database connectoin. Defaults to global $DB. 64 */ 65 public function __construct(moodle_database $db = null) { 66 if (is_null($db)) { 67 global $DB; 68 $this->db = $DB; 69 } else { 70 $this->db = $db; 71 } 72 } 73 74 /** 75 * Store an entire {@link question_usage_by_activity} in the database, 76 * including all the question_attempts that comprise it. 77 * 78 * You should not call this method directly. You should use 79 * @link question_engine::save_questions_usage_by_activity()}. 80 * 81 * @param question_usage_by_activity $quba the usage to store. 82 */ 83 public function insert_questions_usage_by_activity(question_usage_by_activity $quba) { 84 $record = new stdClass(); 85 $record->contextid = $quba->get_owning_context()->id; 86 $record->component = $quba->get_owning_component(); 87 $record->preferredbehaviour = $quba->get_preferred_behaviour(); 88 89 $newid = $this->db->insert_record('question_usages', $record); 90 $quba->set_id_from_database($newid); 91 92 // Initially an array of array of question_attempt_step_objects. 93 // Built as a nested array for efficiency, then flattened. 94 $stepdata = array(); 95 96 foreach ($quba->get_attempt_iterator() as $qa) { 97 $stepdata[] = $this->insert_question_attempt($qa, $quba->get_owning_context()); 98 } 99 100 $this->insert_all_step_data($this->combine_step_data($stepdata)); 101 102 $quba->set_observer(new question_engine_unit_of_work($quba)); 103 } 104 105 /** 106 * Store an entire {@link question_attempt} in the database, 107 * including all the question_attempt_steps that comprise it. 108 * 109 * You should not call this method directly. You should use 110 * @link question_engine::save_questions_usage_by_activity()}. 111 * 112 * @param question_attempt $qa the question attempt to store. 113 * @param context $context the context of the owning question_usage_by_activity. 114 * @return array of question_attempt_step_data rows, that still need to be inserted. 115 */ 116 public function insert_question_attempt(question_attempt $qa, $context) { 117 $record = new stdClass(); 118 $record->questionusageid = $qa->get_usage_id(); 119 $record->slot = $qa->get_slot(); 120 $record->behaviour = $qa->get_behaviour_name(); 121 $record->questionid = $qa->get_question_id(); 122 $record->variant = $qa->get_variant(); 123 $record->maxmark = $qa->get_max_mark(); 124 $record->minfraction = $qa->get_min_fraction(); 125 $record->maxfraction = $qa->get_max_fraction(); 126 $record->flagged = $qa->is_flagged(); 127 $record->questionsummary = $qa->get_question_summary(); 128 if (core_text::strlen($record->questionsummary) > question_bank::MAX_SUMMARY_LENGTH) { 129 // It seems some people write very long quesions! MDL-30760 130 $record->questionsummary = core_text::substr($record->questionsummary, 131 0, question_bank::MAX_SUMMARY_LENGTH - 3) . '...'; 132 } 133 $record->rightanswer = $qa->get_right_answer_summary(); 134 $record->responsesummary = $qa->get_response_summary(); 135 $record->timemodified = time(); 136 $record->id = $this->db->insert_record('question_attempts', $record); 137 $qa->set_database_id($record->id); 138 139 // Initially an array of array of question_attempt_step_objects. 140 // Built as a nested array for efficiency, then flattened. 141 $stepdata = array(); 142 143 foreach ($qa->get_step_iterator() as $seq => $step) { 144 $stepdata[] = $this->insert_question_attempt_step($step, $record->id, $seq, $context); 145 } 146 147 return $this->combine_step_data($stepdata); 148 } 149 150 /** 151 * Helper method used by insert_question_attempt_step and update_question_attempt_step 152 * @param question_attempt_step $step the step to store. 153 * @param int $questionattemptid the question attept id this step belongs to. 154 * @param int $seq the sequence number of this stop. 155 * @return stdClass data to insert into the database. 156 */ 157 protected function make_step_record(question_attempt_step $step, $questionattemptid, $seq) { 158 $record = new stdClass(); 159 $record->questionattemptid = $questionattemptid; 160 $record->sequencenumber = $seq; 161 $record->state = (string) $step->get_state(); 162 $record->fraction = $step->get_fraction(); 163 $record->timecreated = $step->get_timecreated(); 164 $record->userid = $step->get_user_id(); 165 return $record; 166 } 167 168 /** 169 * Take an array of arrays, and flatten it, even if the outer array is empty. 170 * 171 * Only public so it can be called from the unit of work. Not part of the 172 * public API of this class. 173 * 174 * @param array $stepdata array of zero or more arrays. 175 * @return array made by concatenating all the separate arrays. 176 */ 177 public function combine_step_data(array $stepdata): array { 178 if (empty($stepdata)) { 179 return []; 180 } 181 return call_user_func_array('array_merge', $stepdata); 182 } 183 184 /** 185 * Helper method used by insert_question_attempt_step and update_question_attempt_step 186 * @param question_attempt_step $step the step to store. 187 * @param int $stepid the id of the step. 188 * @param context $context the context of the owning question_usage_by_activity. 189 * @return array of question_attempt_step_data rows, that still need to be inserted. 190 */ 191 protected function prepare_step_data(question_attempt_step $step, $stepid, $context) { 192 $rows = array(); 193 foreach ($step->get_all_data() as $name => $value) { 194 if ($value instanceof question_file_saver) { 195 $value->save_files($stepid, $context); 196 } 197 if ($value instanceof question_response_files) { 198 $value = (string) $value; 199 } 200 201 $data = new stdClass(); 202 $data->attemptstepid = $stepid; 203 $data->name = $name; 204 $data->value = $value; 205 $rows[] = $data; 206 } 207 return $rows; 208 } 209 210 /** 211 * Insert a lot of records into question_attempt_step_data in one go. 212 * 213 * Private method, only for use by other parts of the question engine. 214 * 215 * @param array $rows the rows to insert. 216 */ 217 public function insert_all_step_data(array $rows) { 218 if (!$rows) { 219 return; 220 } 221 $this->db->insert_records('question_attempt_step_data', $rows); 222 } 223 224 /** 225 * Store a {@link question_attempt_step} in the database. 226 * 227 * Private method, only for use by other parts of the question engine. 228 * 229 * @param question_attempt_step $step the step to store. 230 * @param int $questionattemptid the question attept id this step belongs to. 231 * @param int $seq the sequence number of this stop. 232 * @param context $context the context of the owning question_usage_by_activity. 233 * @return array of question_attempt_step_data rows, that still need to be inserted. 234 */ 235 public function insert_question_attempt_step(question_attempt_step $step, 236 $questionattemptid, $seq, $context) { 237 238 $record = $this->make_step_record($step, $questionattemptid, $seq); 239 $record->id = $this->db->insert_record('question_attempt_steps', $record); 240 241 return $this->prepare_step_data($step, $record->id, $context); 242 } 243 244 /** 245 * Update a {@link question_attempt_step} in the database. 246 * 247 * Private method, only for use by other parts of the question engine. 248 * 249 * @param question_attempt_step $step the step to store. 250 * @param int $questionattemptid the question attept id this step belongs to. 251 * @param int $seq the sequence number of this stop. 252 * @param context $context the context of the owning question_usage_by_activity. 253 * @return array of question_attempt_step_data rows, that still need to be inserted. 254 */ 255 public function update_question_attempt_step(question_attempt_step $step, 256 $questionattemptid, $seq, $context) { 257 258 $record = $this->make_step_record($step, $questionattemptid, $seq); 259 $record->id = $step->get_id(); 260 $this->db->update_record('question_attempt_steps', $record); 261 262 $this->db->delete_records('question_attempt_step_data', 263 array('attemptstepid' => $record->id)); 264 return $this->prepare_step_data($step, $record->id, $context); 265 } 266 267 /** 268 * Store new metadata for an existing {@link question_attempt} in the database. 269 * 270 * Private method, only for use by other parts of the question engine. 271 * 272 * @param question_attempt $qa the question attempt to store meta data for. 273 * @param array $names the names of the metadata variables to store. 274 * @return array of question_attempt_step_data rows, that still need to be inserted. 275 */ 276 public function insert_question_attempt_metadata(question_attempt $qa, array $names) { 277 $firststep = $qa->get_step(0); 278 279 $rows = array(); 280 foreach ($names as $name) { 281 $data = new stdClass(); 282 $data->attemptstepid = $firststep->get_id(); 283 $data->name = ':_' . $name; 284 $data->value = $firststep->get_metadata_var($name); 285 $rows[] = $data; 286 } 287 288 return $rows; 289 } 290 291 /** 292 * Updates existing metadata for an existing {@link question_attempt} in the database. 293 * 294 * Private method, only for use by other parts of the question engine. 295 * 296 * @param question_attempt $qa the question attempt to store meta data for. 297 * @param array $names the names of the metadata variables to store. 298 * @return array of question_attempt_step_data rows, that still need to be inserted. 299 */ 300 public function update_question_attempt_metadata(question_attempt $qa, array $names) { 301 global $DB; 302 if (!$names) { 303 return []; 304 } 305 // Use case-sensitive function sql_equal() and not get_in_or_equal(). 306 // Some databases may use case-insensitive collation, we don't want to delete 'X' instead of 'x'. 307 $sqls = []; 308 $params = [$qa->get_step(0)->get_id()]; 309 foreach ($names as $name) { 310 $sqls[] = $DB->sql_equal('name', '?'); 311 $params[] = $name; 312 } 313 $DB->delete_records_select('question_attempt_step_data', 314 'attemptstepid = ? AND (' . join(' OR ', $sqls) . ')', $params); 315 return $this->insert_question_attempt_metadata($qa, $names); 316 } 317 318 /** 319 * Load a {@link question_attempt_step} from the database. 320 * 321 * Private method, only for use by other parts of the question engine. 322 * 323 * @param int $stepid the id of the step to load. 324 * @return question_attempt_step the step that was loaded. 325 */ 326 public function load_question_attempt_step($stepid) { 327 $records = $this->db->get_recordset_sql(" 328 SELECT 329 quba.contextid, 330 COALESCE(q.qtype, 'missingtype') AS qtype, 331 qas.id AS attemptstepid, 332 qas.questionattemptid, 333 qas.sequencenumber, 334 qas.state, 335 qas.fraction, 336 qas.timecreated, 337 qas.userid, 338 qasd.name, 339 qasd.value 340 341 FROM {question_attempt_steps} qas 342 JOIN {question_attempts} qa ON qa.id = qas.questionattemptid 343 JOIN {question_usages} quba ON quba.id = qa.questionusageid 344 LEFT JOIN {question} q ON q.id = qa.questionid 345 LEFT JOIN {question_attempt_step_data} qasd ON qasd.attemptstepid = qas.id 346 347 WHERE 348 qas.id = :stepid 349 ", array('stepid' => $stepid)); 350 351 if (!$records->valid()) { 352 throw new coding_exception('Failed to load question_attempt_step ' . $stepid); 353 } 354 355 $step = question_attempt_step::load_from_records($records, $stepid); 356 $records->close(); 357 358 return $step; 359 } 360 361 /** 362 * Load a {@link question_attempt} from the database, including all its 363 * steps. 364 * 365 * Normally, you should use {@link question_engine::load_questions_usage_by_activity()} 366 * but there may be rare occasions where for performance reasons, you only 367 * wish to load one qa, in which case you may call this method. 368 * 369 * @param int $questionattemptid the id of the question attempt to load. 370 * @return question_attempt the question attempt that was loaded. 371 */ 372 public function load_question_attempt($questionattemptid) { 373 $records = $this->db->get_recordset_sql(" 374 SELECT 375 quba.contextid, 376 quba.preferredbehaviour, 377 qa.id AS questionattemptid, 378 qa.questionusageid, 379 qa.slot, 380 qa.behaviour, 381 qa.questionid, 382 qa.variant, 383 qa.maxmark, 384 qa.minfraction, 385 qa.maxfraction, 386 qa.flagged, 387 qa.questionsummary, 388 qa.rightanswer, 389 qa.responsesummary, 390 qa.timemodified, 391 qas.id AS attemptstepid, 392 qas.sequencenumber, 393 qas.state, 394 qas.fraction, 395 qas.timecreated, 396 qas.userid, 397 qasd.name, 398 qasd.value 399 400 FROM {question_attempts} qa 401 JOIN {question_usages} quba ON quba.id = qa.questionusageid 402 LEFT JOIN {question_attempt_steps} qas ON qas.questionattemptid = qa.id 403 LEFT JOIN {question_attempt_step_data} qasd ON qasd.attemptstepid = qas.id 404 405 WHERE 406 qa.id = :questionattemptid 407 408 ORDER BY 409 qas.sequencenumber 410 ", array('questionattemptid' => $questionattemptid)); 411 412 if (!$records->valid()) { 413 throw new coding_exception('Failed to load question_attempt ' . $questionattemptid); 414 } 415 416 $record = $records->current(); 417 $qa = question_attempt::load_from_records($records, $questionattemptid, 418 new question_usage_null_observer(), $record->preferredbehaviour); 419 $records->close(); 420 421 return $qa; 422 } 423 424 /** 425 * Load a {@link question_usage_by_activity} from the database, including 426 * all its {@link question_attempt}s and all their steps. 427 * 428 * You should call {@link question_engine::load_questions_usage_by_activity()} 429 * rather than calling this method directly. 430 * 431 * @param int $qubaid the id of the usage to load. 432 * @return question_usage_by_activity the usage that was loaded. 433 */ 434 public function load_questions_usage_by_activity($qubaid) { 435 $records = $this->db->get_recordset_sql(" 436 SELECT 437 quba.id AS qubaid, 438 quba.contextid, 439 quba.component, 440 quba.preferredbehaviour, 441 qa.id AS questionattemptid, 442 qa.questionusageid, 443 qa.slot, 444 qa.behaviour, 445 qa.questionid, 446 qa.variant, 447 qa.maxmark, 448 qa.minfraction, 449 qa.maxfraction, 450 qa.flagged, 451 qa.questionsummary, 452 qa.rightanswer, 453 qa.responsesummary, 454 qa.timemodified, 455 qas.id AS attemptstepid, 456 qas.sequencenumber, 457 qas.state, 458 qas.fraction, 459 qas.timecreated, 460 qas.userid, 461 qasd.name, 462 qasd.value 463 464 FROM {question_usages} quba 465 LEFT JOIN {question_attempts} qa ON qa.questionusageid = quba.id 466 LEFT JOIN {question_attempt_steps} qas ON qas.questionattemptid = qa.id 467 LEFT JOIN {question_attempt_step_data} qasd ON qasd.attemptstepid = qas.id 468 469 WHERE 470 quba.id = :qubaid 471 472 ORDER BY 473 qa.slot, 474 qas.sequencenumber 475 ", array('qubaid' => $qubaid)); 476 477 if (!$records->valid()) { 478 throw new coding_exception('Failed to load questions_usage_by_activity ' . $qubaid); 479 } 480 481 $quba = question_usage_by_activity::load_from_records($records, $qubaid); 482 $records->close(); 483 484 return $quba; 485 } 486 487 /** 488 * Load all {@link question_usage_by_activity} from the database for one qubaid_condition 489 * Include all its {@link question_attempt}s and all their steps. 490 * 491 * This method may be called publicly. 492 * 493 * @param qubaid_condition $qubaids the condition that tells us which usages to load. 494 * @return question_usage_by_activity[] the usages that were loaded. 495 */ 496 public function load_questions_usages_by_activity($qubaids) { 497 $records = $this->db->get_recordset_sql(" 498 SELECT 499 quba.id AS qubaid, 500 quba.contextid, 501 quba.component, 502 quba.preferredbehaviour, 503 qa.id AS questionattemptid, 504 qa.questionusageid, 505 qa.slot, 506 qa.behaviour, 507 qa.questionid, 508 qa.variant, 509 qa.maxmark, 510 qa.minfraction, 511 qa.maxfraction, 512 qa.flagged, 513 qa.questionsummary, 514 qa.rightanswer, 515 qa.responsesummary, 516 qa.timemodified, 517 qas.id AS attemptstepid, 518 qas.sequencenumber, 519 qas.state, 520 qas.fraction, 521 qas.timecreated, 522 qas.userid, 523 qasd.name, 524 qasd.value 525 526 FROM {question_usages} quba 527 LEFT JOIN {question_attempts} qa ON qa.questionusageid = quba.id 528 LEFT JOIN {question_attempt_steps} qas ON qas.questionattemptid = qa.id 529 LEFT JOIN {question_attempt_step_data} qasd ON qasd.attemptstepid = qas.id 530 531 WHERE 532 quba.id {$qubaids->usage_id_in()} 533 534 ORDER BY 535 quba.id, 536 qa.slot, 537 qas.sequencenumber 538 ", $qubaids->usage_id_in_params()); 539 540 $qubas = array(); 541 while ($records->valid()) { 542 $record = $records->current(); 543 $qubas[$record->qubaid] = question_usage_by_activity::load_from_records($records, $record->qubaid); 544 } 545 546 $records->close(); 547 548 return $qubas; 549 } 550 551 /** 552 * Load information about the latest state of each question from the database. 553 * 554 * This method may be called publicly. 555 * 556 * @param qubaid_condition $qubaids used to restrict which usages are included 557 * in the query. See {@link qubaid_condition}. 558 * @param array|null $slots (optional) list of slots for which to return information. Default all slots. 559 * @param string|null $fields 560 * @return array of records. See the SQL in this function to see the fields available. 561 */ 562 public function load_questions_usages_latest_steps(qubaid_condition $qubaids, $slots = null, $fields = null) { 563 if ($slots !== null) { 564 [$slottest, $params] = $this->db->get_in_or_equal($slots, SQL_PARAMS_NAMED, 'slot'); 565 $slotwhere = " AND qa.slot {$slottest}"; 566 } else { 567 $slotwhere = ''; 568 $params = []; 569 } 570 571 if ($fields === null) { 572 $fields = "qas.id, 573 qa.id AS questionattemptid, 574 qa.questionusageid, 575 qa.slot, 576 qa.behaviour, 577 qa.questionid, 578 qa.variant, 579 qa.maxmark, 580 qa.minfraction, 581 qa.maxfraction, 582 qa.flagged, 583 qa.questionsummary, 584 qa.rightanswer, 585 qa.responsesummary, 586 qa.timemodified, 587 qas.id AS attemptstepid, 588 qas.sequencenumber, 589 qas.state, 590 qas.fraction, 591 qas.timecreated, 592 qas.userid"; 593 594 } 595 596 $records = $this->db->get_records_sql(" 597 SELECT 598 {$fields} 599 600 FROM {$qubaids->from_question_attempts('qa')} 601 JOIN {question_attempt_steps} qas ON qas.questionattemptid = qa.id 602 AND qas.sequencenumber = {$this->latest_step_for_qa_subquery()} 603 604 WHERE 605 {$qubaids->where()} 606 $slotwhere 607 ", $params + $qubaids->from_where_params()); 608 609 return $records; 610 } 611 612 /** 613 * Load summary information about the state of each question in a group of 614 * attempts. This is used, for example, by the quiz manual grading report, 615 * to show how many attempts at each question need to be graded. 616 * 617 * This method may be called publicly. 618 * 619 * @param qubaid_condition $qubaids used to restrict which usages are included 620 * in the query. See {@link qubaid_condition}. 621 * @param array|null $slots (optional) list of slots for which to return information. Default all slots. 622 * @return array The array keys are 'slot,questionid'. The values are objects with 623 * fields $slot, $questionid, $inprogress, $name, $needsgrading, $autograded, 624 * $manuallygraded and $all. 625 */ 626 public function load_questions_usages_question_state_summary(qubaid_condition $qubaids, $slots = null) { 627 if ($slots !== null) { 628 [$slottest, $params] = $this->db->get_in_or_equal($slots, SQL_PARAMS_NAMED, 'slot'); 629 $slotwhere = " AND qa.slot {$slottest}"; 630 } else { 631 $slotwhere = ''; 632 $params = []; 633 } 634 635 $rs = $this->db->get_recordset_sql(" 636 SELECT 637 qa.slot, 638 qa.questionid, 639 q.name, 640 CASE qas.state 641 {$this->full_states_to_summary_state_sql()} 642 END AS summarystate, 643 COUNT(1) AS numattempts 644 645 FROM {$qubaids->from_question_attempts('qa')} 646 JOIN {question_attempt_steps} qas ON qas.questionattemptid = qa.id 647 AND qas.sequencenumber = {$this->latest_step_for_qa_subquery()} 648 JOIN {question} q ON q.id = qa.questionid 649 650 WHERE 651 {$qubaids->where()} 652 $slotwhere 653 654 GROUP BY 655 qa.slot, 656 qa.questionid, 657 q.name, 658 q.id, 659 CASE qas.state 660 {$this->full_states_to_summary_state_sql()} 661 END 662 663 ORDER BY 664 qa.slot, 665 qa.questionid, 666 q.name, 667 q.id 668 ", $params + $qubaids->from_where_params()); 669 670 $results = array(); 671 foreach ($rs as $row) { 672 $index = $row->slot . ',' . $row->questionid; 673 674 if (!array_key_exists($index, $results)) { 675 $res = new stdClass(); 676 $res->slot = $row->slot; 677 $res->questionid = $row->questionid; 678 $res->name = $row->name; 679 $res->inprogress = 0; 680 $res->needsgrading = 0; 681 $res->autograded = 0; 682 $res->manuallygraded = 0; 683 $res->all = 0; 684 $results[$index] = $res; 685 } 686 687 $results[$index]->{$row->summarystate} = $row->numattempts; 688 $results[$index]->all += $row->numattempts; 689 } 690 $rs->close(); 691 692 return $results; 693 } 694 695 /** 696 * Get a list of usage ids where the question with slot $slot, and optionally 697 * also with question id $questionid, is in summary state $summarystate. Also 698 * return the total count of such states. 699 * 700 * Only a subset of the ids can be returned by using $orderby, $limitfrom and 701 * $limitnum. A special value 'random' can be passed as $orderby, in which case 702 * $limitfrom is ignored. 703 * 704 * This method may be called publicly. 705 * 706 * @param qubaid_condition $qubaids used to restrict which usages are included 707 * in the query. See {@link qubaid_condition}. 708 * @param int $slot The slot for the questions you want to know about. 709 * @param int $questionid (optional) Only return attempts that were of this specific question. 710 * @param string $summarystate the summary state of interest, or 'all'. 711 * @param string $orderby the column to order by. 712 * @param array $params any params required by any of the SQL fragments. 713 * @param int $limitfrom implements paging of the results. 714 * Ignored if $orderby = random or $limitnum is null. 715 * @param int $limitnum implements paging of the results. null = all. 716 * @return array with two elements, an array of usage ids, and a count of the total number. 717 */ 718 public function load_questions_usages_where_question_in_state( 719 qubaid_condition $qubaids, $summarystate, $slot, $questionid = null, 720 $orderby = 'random', $params = array(), $limitfrom = 0, $limitnum = null) { 721 722 $extrawhere = ''; 723 if ($questionid) { 724 $extrawhere .= ' AND qa.questionid = :questionid'; 725 $params['questionid'] = $questionid; 726 } 727 if ($summarystate != 'all') { 728 list($test, $sparams) = $this->in_summary_state_test($summarystate); 729 $extrawhere .= ' AND qas.state ' . $test; 730 $params += $sparams; 731 } 732 733 if ($orderby == 'random') { 734 $sqlorderby = ''; 735 } else if ($orderby) { 736 $sqlorderby = 'ORDER BY ' . $orderby; 737 } else { 738 $sqlorderby = ''; 739 } 740 741 // We always want the total count, as well as the partcular list of ids 742 // based on the paging and sort order. Because the list of ids is never 743 // going to be too ridiculously long. My worst-case scenario is 744 // 10,000 students in the course, each doing 5 quiz attempts. That 745 // is a 50,000 element int => int array, which PHP seems to use 5MB 746 // memory to store on a 64 bit server. 747 $qubaidswhere = $qubaids->where(); // Must call this before params. 748 $params += $qubaids->from_where_params(); 749 $params['slot'] = $slot; 750 751 $qubaids = $this->db->get_records_sql_menu(" 752 SELECT 753 qa.questionusageid, 754 1 755 756 FROM {$qubaids->from_question_attempts('qa')} 757 JOIN {question_attempt_steps} qas ON qas.questionattemptid = qa.id 758 AND qas.sequencenumber = {$this->latest_step_for_qa_subquery()} 759 JOIN {question} q ON q.id = qa.questionid 760 761 WHERE 762 {$qubaidswhere} AND 763 qa.slot = :slot 764 $extrawhere 765 766 $sqlorderby 767 ", $params); 768 769 $qubaids = array_keys($qubaids); 770 $count = count($qubaids); 771 772 if ($orderby == 'random') { 773 shuffle($qubaids); 774 $limitfrom = 0; 775 } 776 777 if (!is_null($limitnum)) { 778 $qubaids = array_slice($qubaids, $limitfrom, $limitnum); 779 } 780 781 return array($qubaids, $count); 782 } 783 784 /** 785 * Load the average mark, and number of attempts, for each slot in a set of 786 * question usages.. 787 * 788 * This method may be called publicly. 789 * 790 * @param qubaid_condition $qubaids used to restrict which usages are included 791 * in the query. See {@link qubaid_condition}. 792 * @param array|null $slots if null, load info for all quesitions, otherwise only 793 * load the averages for the specified questions. 794 * @return array of objects with fields ->slot, ->averagefraction and ->numaveraged. 795 */ 796 public function load_average_marks(qubaid_condition $qubaids, $slots = null) { 797 if (!empty($slots)) { 798 list($slottest, $slotsparams) = $this->db->get_in_or_equal( 799 $slots, SQL_PARAMS_NAMED, 'slot'); 800 $slotwhere = " AND qa.slot {$slottest}"; 801 } else { 802 $slotwhere = ''; 803 $slotsparams = array(); 804 } 805 806 list($statetest, $stateparams) = $this->db->get_in_or_equal(array( 807 (string) question_state::$gaveup, 808 (string) question_state::$gradedwrong, 809 (string) question_state::$gradedpartial, 810 (string) question_state::$gradedright, 811 (string) question_state::$mangaveup, 812 (string) question_state::$mangrwrong, 813 (string) question_state::$mangrpartial, 814 (string) question_state::$mangrright), SQL_PARAMS_NAMED, 'st'); 815 816 return $this->db->get_records_sql(" 817 SELECT 818 qa.slot, 819 AVG(COALESCE(qas.fraction, 0)) AS averagefraction, 820 COUNT(1) AS numaveraged 821 822 FROM {$qubaids->from_question_attempts('qa')} 823 JOIN {question_attempt_steps} qas ON qas.questionattemptid = qa.id 824 AND qas.sequencenumber = {$this->latest_step_for_qa_subquery()} 825 826 WHERE 827 {$qubaids->where()} 828 $slotwhere 829 AND qas.state $statetest 830 831 GROUP BY qa.slot 832 833 ORDER BY qa.slot 834 ", $slotsparams + $stateparams + $qubaids->from_where_params()); 835 } 836 837 /** 838 * Load all the attempts at a given queston from a set of question_usages. 839 * steps. 840 * 841 * This method may be called publicly. 842 * 843 * @param int $questionid the question to load all the attempts fors. 844 * @param qubaid_condition $qubaids used to restrict which usages are included 845 * in the query. See {@link qubaid_condition}. 846 * @return question_attempt[] array of question_attempts that were loaded. 847 */ 848 public function load_attempts_at_question($questionid, qubaid_condition $qubaids) { 849 $sql = " 850 SELECT 851 quba.contextid, 852 quba.preferredbehaviour, 853 qa.id AS questionattemptid, 854 qa.questionusageid, 855 qa.slot, 856 qa.behaviour, 857 qa.questionid, 858 qa.variant, 859 qa.maxmark, 860 qa.minfraction, 861 qa.maxfraction, 862 qa.flagged, 863 qa.questionsummary, 864 qa.rightanswer, 865 qa.responsesummary, 866 qa.timemodified, 867 qas.id AS attemptstepid, 868 qas.sequencenumber, 869 qas.state, 870 qas.fraction, 871 qas.timecreated, 872 qas.userid, 873 qasd.name, 874 qasd.value 875 876 FROM {$qubaids->from_question_attempts('qa')} 877 JOIN {question_usages} quba ON quba.id = qa.questionusageid 878 LEFT JOIN {question_attempt_steps} qas ON qas.questionattemptid = qa.id 879 LEFT JOIN {question_attempt_step_data} qasd ON qasd.attemptstepid = qas.id 880 881 WHERE 882 {$qubaids->where()} AND 883 qa.questionid = :questionid 884 885 ORDER BY 886 quba.id, 887 qa.id, 888 qas.sequencenumber"; 889 890 // For qubaid_list must call this after calling methods that generate sql. 891 $params = $qubaids->from_where_params(); 892 $params['questionid'] = $questionid; 893 894 $records = $this->db->get_recordset_sql($sql, $params); 895 896 $questionattempts = array(); 897 while ($records->valid()) { 898 $record = $records->current(); 899 $questionattempts[$record->questionattemptid] = 900 question_attempt::load_from_records($records, 901 $record->questionattemptid, new question_usage_null_observer(), 902 $record->preferredbehaviour); 903 } 904 $records->close(); 905 906 return $questionattempts; 907 } 908 909 /** 910 * Update a question_usages row to refect any changes in a usage (but not 911 * any of its question_attempts. 912 * 913 * You should not call this method directly. You should use 914 * @link question_engine::save_questions_usage_by_activity()}. 915 * 916 * @param question_usage_by_activity $quba the usage that has changed. 917 */ 918 public function update_questions_usage_by_activity(question_usage_by_activity $quba) { 919 $record = new stdClass(); 920 $record->id = $quba->get_id(); 921 $record->contextid = $quba->get_owning_context()->id; 922 $record->component = $quba->get_owning_component(); 923 $record->preferredbehaviour = $quba->get_preferred_behaviour(); 924 925 $this->db->update_record('question_usages', $record); 926 } 927 928 /** 929 * Update a question_attempts row to refect any changes in a question_attempt 930 * (but not any of its steps). 931 * 932 * You should not call this method directly. You should use 933 * @link question_engine::save_questions_usage_by_activity()}. 934 * 935 * @param question_attempt $qa the question attempt that has changed. 936 */ 937 public function update_question_attempt(question_attempt $qa) { 938 $record = new stdClass(); 939 $record->id = $qa->get_database_id(); 940 $record->slot = $qa->get_slot(); 941 $record->variant = $qa->get_variant(); 942 $record->maxmark = $qa->get_max_mark(); 943 $record->minfraction = $qa->get_min_fraction(); 944 $record->maxfraction = $qa->get_max_fraction(); 945 $record->flagged = $qa->is_flagged(); 946 $record->questionsummary = $qa->get_question_summary(); 947 $record->rightanswer = $qa->get_right_answer_summary(); 948 $record->responsesummary = $qa->get_response_summary(); 949 $record->timemodified = time(); 950 951 $this->db->update_record('question_attempts', $record); 952 } 953 954 /** 955 * Delete a question_usage_by_activity and all its associated 956 * 957 * You should not call this method directly. You should use 958 * @link question_engine::delete_questions_usage_by_activities()}. 959 * 960 * {@link question_attempts} and {@link question_attempt_steps} from the 961 * database. 962 * @param qubaid_condition $qubaids identifies which question useages to delete. 963 */ 964 public function delete_questions_usage_by_activities(qubaid_condition $qubaids) { 965 $where = "qa.questionusageid {$qubaids->usage_id_in()}"; 966 $params = $qubaids->usage_id_in_params(); 967 968 $contextids = $this->db->get_records_sql_menu(" 969 SELECT DISTINCT contextid, 1 970 FROM {question_usages} 971 WHERE id {$qubaids->usage_id_in()}", $qubaids->usage_id_in_params()); 972 foreach ($contextids as $contextid => $notused) { 973 $this->delete_response_files($contextid, "IN ( 974 SELECT qas.id 975 FROM {question_attempts} qa 976 JOIN {question_attempt_steps} qas ON qas.questionattemptid = qa.id 977 WHERE $where)", $params); 978 } 979 980 if ($this->db->get_dbfamily() == 'mysql') { 981 $this->delete_usage_records_for_mysql($qubaids); 982 return; 983 } 984 985 $this->db->delete_records_select('question_attempt_step_data', "attemptstepid IN ( 986 SELECT qas.id 987 FROM {question_attempts} qa 988 JOIN {question_attempt_steps} qas ON qas.questionattemptid = qa.id 989 WHERE $where)", $params); 990 991 $this->db->delete_records_select('question_attempt_steps', "questionattemptid IN ( 992 SELECT qa.id 993 FROM {question_attempts} qa 994 WHERE $where)", $params); 995 996 $this->db->delete_records_select('question_attempts', 997 "{question_attempts}.questionusageid {$qubaids->usage_id_in()}", 998 $qubaids->usage_id_in_params()); 999 1000 $this->db->delete_records_select('question_usages', 1001 "{question_usages}.id {$qubaids->usage_id_in()}", $qubaids->usage_id_in_params()); 1002 } 1003 1004 /** 1005 * This function is a work-around for poor MySQL performance with 1006 * DELETE FROM x WHERE id IN (SELECT ...). We have to use a non-standard 1007 * syntax to get good performance. See MDL-29520. 1008 * @param qubaid_condition $qubaids identifies which question useages to delete. 1009 */ 1010 protected function delete_usage_records_for_mysql(qubaid_condition $qubaids) { 1011 // Get the list of question attempts to delete and delete them in chunks. 1012 $allids = $this->db->get_records_sql_menu(" 1013 SELECT DISTINCT id, id AS id2 1014 FROM {question_usages} 1015 WHERE id " . $qubaids->usage_id_in(), 1016 $qubaids->usage_id_in_params()); 1017 1018 foreach (array_chunk($allids, 1000) as $todelete) { 1019 list($idsql, $idparams) = $this->db->get_in_or_equal($todelete); 1020 $this->db->execute(' 1021 DELETE qu, qa, qas, qasd 1022 FROM {question_usages} qu 1023 JOIN {question_attempts} qa ON qa.questionusageid = qu.id 1024 LEFT JOIN {question_attempt_steps} qas ON qas.questionattemptid = qa.id 1025 LEFT JOIN {question_attempt_step_data} qasd ON qasd.attemptstepid = qas.id 1026 WHERE qu.id ' . $idsql, 1027 $idparams); 1028 } 1029 } 1030 1031 /** 1032 * Delete some steps of a question attempt. 1033 * 1034 * Private method, only for use by other parts of the question engine. 1035 * 1036 * @param array $stepids array of step ids to delete. 1037 * @param context $context the context that the $quba belongs to. 1038 */ 1039 public function delete_steps($stepids, $context) { 1040 if (empty($stepids)) { 1041 return; 1042 } 1043 list($test, $params) = $this->db->get_in_or_equal($stepids, SQL_PARAMS_NAMED); 1044 1045 $this->delete_response_files($context->id, $test, $params); 1046 1047 $this->db->delete_records_select('question_attempt_step_data', 1048 "attemptstepid {$test}", $params); 1049 $this->db->delete_records_select('question_attempt_steps', 1050 "id {$test}", $params); 1051 } 1052 1053 /** 1054 * Delete all the files belonging to the response variables in the gives 1055 * question attempt steps. 1056 * @param int $contextid the context these attempts belong to. 1057 * @param string $itemidstest a bit of SQL that can be used in a 1058 * WHERE itemid $itemidstest clause. Must use named params. 1059 * @param array $params any query parameters used in $itemidstest. 1060 */ 1061 protected function delete_response_files($contextid, $itemidstest, $params) { 1062 $fs = get_file_storage(); 1063 foreach (question_engine::get_all_response_file_areas() as $filearea) { 1064 $fs->delete_area_files_select($contextid, 'question', $filearea, 1065 $itemidstest, $params); 1066 } 1067 } 1068 1069 /** 1070 * Delete all the previews for a given question. 1071 * 1072 * Private method, only for use by other parts of the question engine. 1073 * 1074 * @param int $questionid question id. 1075 */ 1076 public function delete_previews($questionid) { 1077 $previews = $this->db->get_records_sql_menu(" 1078 SELECT DISTINCT quba.id, 1 1079 FROM {question_usages} quba 1080 JOIN {question_attempts} qa ON qa.questionusageid = quba.id 1081 WHERE quba.component = 'core_question_preview' AND 1082 qa.questionid = ?", array($questionid)); 1083 if (empty($previews)) { 1084 return; 1085 } 1086 $this->delete_questions_usage_by_activities(new qubaid_list($previews)); 1087 } 1088 1089 /** 1090 * Update the flagged state of a question in the database. 1091 * 1092 * You should call {@link question_engine::update_flag()()} 1093 * rather than calling this method directly. 1094 * 1095 * @param int $qubaid the question usage id. 1096 * @param int $questionid the question id. 1097 * @param int $qaid the question_attempt id. 1098 * @param int $slot the slot number of the question attempt to update. 1099 * @param bool $newstate the new state of the flag. true = flagged. 1100 */ 1101 public function update_question_attempt_flag($qubaid, $questionid, $qaid, $slot, $newstate) { 1102 if (!$this->db->record_exists('question_attempts', array('id' => $qaid, 1103 'questionusageid' => $qubaid, 'questionid' => $questionid, 'slot' => $slot))) { 1104 throw new moodle_exception('errorsavingflags', 'question'); 1105 } 1106 1107 $this->db->set_field('question_attempts', 'flagged', $newstate, array('id' => $qaid)); 1108 } 1109 1110 /** 1111 * Get all the WHEN 'x' THEN 'y' terms needed to convert the question_attempt_steps.state 1112 * column to a summary state. Use this like 1113 * CASE qas.state {$this->full_states_to_summary_state_sql()} END AS summarystate, 1114 * 1115 * @return string SQL fragment. 1116 */ 1117 protected function full_states_to_summary_state_sql() { 1118 $sql = ''; 1119 foreach (question_state::get_all() as $state) { 1120 $sql .= "WHEN '{$state}' THEN '{$state->get_summary_state()}'\n"; 1121 } 1122 return $sql; 1123 } 1124 1125 /** 1126 * Get the SQL needed to test that question_attempt_steps.state is in a 1127 * state corresponding to $summarystate. 1128 * 1129 * This method may be called publicly. 1130 * 1131 * @param string $summarystate one of 1132 * inprogress, needsgrading, manuallygraded or autograded 1133 * @param bool $equal if false, do a NOT IN test. Default true. 1134 * @param string $prefix used in the call to $DB->get_in_or_equal(). 1135 * @return array as returned by $DB->get_in_or_equal(). 1136 */ 1137 public function in_summary_state_test($summarystate, $equal = true, $prefix = 'summarystates') { 1138 $states = question_state::get_all_for_summary_state($summarystate); 1139 return $this->db->get_in_or_equal(array_map('strval', $states), 1140 SQL_PARAMS_NAMED, $prefix, $equal); 1141 } 1142 1143 /** 1144 * Change the maxmark for the question_attempt with number in usage $slot 1145 * for all the specified question_attempts. 1146 * 1147 * You should call {@link question_engine::set_max_mark_in_attempts()} 1148 * rather than calling this method directly. 1149 * 1150 * @param qubaid_condition $qubaids Selects which usages are updated. 1151 * @param int $slot the number is usage to affect. 1152 * @param number $newmaxmark the new max mark to set. 1153 */ 1154 public function set_max_mark_in_attempts(qubaid_condition $qubaids, $slot, $newmaxmark) { 1155 if ($this->db->get_dbfamily() == 'mysql') { 1156 // MySQL's query optimiser completely fails to cope with the 1157 // set_field_select call below, so we have to give it a clue. See MDL-32616. 1158 // TODO MDL-29589 encapsulate this MySQL-specific code with a $DB method. 1159 $this->db->execute(" 1160 UPDATE " . $qubaids->from_question_attempts('qa') . " 1161 SET qa.maxmark = :newmaxmark 1162 WHERE " . $qubaids->where() . " 1163 AND slot = :slot 1164 ", $qubaids->from_where_params() + array('newmaxmark' => $newmaxmark, 'slot' => $slot)); 1165 return; 1166 } 1167 1168 // Normal databases. 1169 $this->db->set_field_select('question_attempts', 'maxmark', $newmaxmark, 1170 "questionusageid {$qubaids->usage_id_in()} AND slot = :slot", 1171 $qubaids->usage_id_in_params() + array('slot' => $slot)); 1172 } 1173 1174 /** 1175 * Return a subquery that computes the sum of the marks for all the questions 1176 * in a usage. Which useage to compute the sum for is controlled bu the $qubaid 1177 * parameter. 1178 * 1179 * See {@link quiz_update_all_attempt_sumgrades()} for an example of the usage of 1180 * this method. 1181 * 1182 * This method may be called publicly. 1183 * 1184 * @param string $qubaid SQL fragment that controls which usage is summed. 1185 * This will normally be the name of a column in the outer query. Not that this 1186 * SQL fragment must not contain any placeholders. 1187 * @return string SQL code for the subquery. 1188 */ 1189 public function sum_usage_marks_subquery($qubaid) { 1190 // To explain the COALESCE in the following SQL: SUM(lots of NULLs) gives 1191 // NULL, while SUM(one 0.0 and lots of NULLS) gives 0.0. We don't want that. 1192 // We always want to return a number, so the COALESCE is there to turn the 1193 // NULL total into a 0. 1194 return "SELECT COALESCE(SUM(qa.maxmark * qas.fraction), 0) 1195 FROM {question_attempts} qa 1196 JOIN {question_attempt_steps} qas ON qas.questionattemptid = qa.id 1197 AND qas.sequencenumber = ( 1198 SELECT MAX(summarks_qas.sequencenumber) 1199 FROM {question_attempt_steps} summarks_qas 1200 WHERE summarks_qas.questionattemptid = qa.id 1201 ) 1202 WHERE qa.questionusageid = $qubaid 1203 HAVING COUNT(CASE 1204 WHEN qas.state = 'needsgrading' AND qa.maxmark > 0 THEN 1 1205 ELSE NULL 1206 END) = 0"; 1207 } 1208 1209 /** 1210 * Get a subquery that returns the latest step of every qa in some qubas. 1211 * Currently, this is only used by the quiz reports. See 1212 * {@link quiz_attempts_report_table::add_latest_state_join()}. 1213 * 1214 * This method may be called publicly. 1215 * 1216 * @param string $alias alias to use for this inline-view. 1217 * @param qubaid_condition $qubaids restriction on which question_usages we 1218 * are interested in. This is important for performance. 1219 * @return array with two elements, the SQL fragment and any params requried. 1220 */ 1221 public function question_attempt_latest_state_view($alias, qubaid_condition $qubaids) { 1222 return array("( 1223 SELECT {$alias}qa.id AS questionattemptid, 1224 {$alias}qa.questionusageid, 1225 {$alias}qa.slot, 1226 {$alias}qa.behaviour, 1227 {$alias}qa.questionid, 1228 {$alias}qa.variant, 1229 {$alias}qa.maxmark, 1230 {$alias}qa.minfraction, 1231 {$alias}qa.maxfraction, 1232 {$alias}qa.flagged, 1233 {$alias}qa.questionsummary, 1234 {$alias}qa.rightanswer, 1235 {$alias}qa.responsesummary, 1236 {$alias}qa.timemodified, 1237 {$alias}qas.id AS attemptstepid, 1238 {$alias}qas.sequencenumber, 1239 {$alias}qas.state, 1240 {$alias}qas.fraction, 1241 {$alias}qas.timecreated, 1242 {$alias}qas.userid 1243 1244 FROM {$qubaids->from_question_attempts($alias . 'qa')} 1245 JOIN {question_attempt_steps} {$alias}qas ON {$alias}qas.questionattemptid = {$alias}qa.id 1246 AND {$alias}qas.sequencenumber = {$this->latest_step_for_qa_subquery($alias . 'qa.id')} 1247 WHERE {$qubaids->where()} 1248 ) {$alias}", $qubaids->from_where_params()); 1249 } 1250 1251 protected function latest_step_for_qa_subquery($questionattemptid = 'qa.id') { 1252 return "( 1253 SELECT MAX(sequencenumber) 1254 FROM {question_attempt_steps} 1255 WHERE questionattemptid = $questionattemptid 1256 )"; 1257 } 1258 1259 /** 1260 * Are any of these questions are currently in use? 1261 * 1262 * You should call {@link question_engine::questions_in_use()} 1263 * rather than calling this method directly. 1264 * 1265 * @param array $questionids of question ids. 1266 * @param qubaid_condition $qubaids ids of the usages to consider. 1267 * @return bool whether any of these questions are being used by any of 1268 * those usages. 1269 */ 1270 public function questions_in_use(array $questionids, qubaid_condition $qubaids) { 1271 list($test, $params) = $this->db->get_in_or_equal($questionids); 1272 return $this->db->record_exists_select('question_attempts', 1273 'questionid ' . $test . ' AND questionusageid ' . 1274 $qubaids->usage_id_in(), $params + $qubaids->usage_id_in_params()); 1275 } 1276 1277 /** 1278 * Get the number of times each variant has been used for each question in a list 1279 * in a set of usages. 1280 * @param array $questionids of question ids. 1281 * @param qubaid_condition $qubaids ids of the usages to consider. 1282 * @return array questionid => variant number => num uses. 1283 */ 1284 public function load_used_variants(array $questionids, qubaid_condition $qubaids) { 1285 list($test, $params) = $this->db->get_in_or_equal($questionids, SQL_PARAMS_NAMED, 'qid'); 1286 $recordset = $this->db->get_recordset_sql(" 1287 SELECT qa.questionid, qa.variant, COUNT(1) AS usescount 1288 FROM " . $qubaids->from_question_attempts('qa') . " 1289 WHERE qa.questionid $test 1290 AND " . $qubaids->where() . " 1291 GROUP BY qa.questionid, qa.variant 1292 ORDER BY COUNT(1) ASC 1293 ", $params + $qubaids->from_where_params()); 1294 1295 $usedvariants = array_combine($questionids, array_fill(0, count($questionids), array())); 1296 foreach ($recordset as $row) { 1297 $usedvariants[$row->questionid][$row->variant] = $row->usescount; 1298 } 1299 $recordset->close(); 1300 return $usedvariants; 1301 } 1302 } 1303 1304 1305 /** 1306 * Implementation of the unit of work pattern for the question engine. 1307 * 1308 * See http://martinfowler.com/eaaCatalog/unitOfWork.html. This tracks all the 1309 * changes to a {@link question_usage_by_activity}, and its constituent parts, 1310 * so that the changes can be saved to the database when {@link save()} is called. 1311 * 1312 * @copyright 2009 The Open University 1313 * @license http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later 1314 */ 1315 class question_engine_unit_of_work implements question_usage_observer { 1316 /** @var question_usage_by_activity the usage being tracked. */ 1317 protected $quba; 1318 1319 /** @var boolean whether any of the fields of the usage have been changed. */ 1320 protected $modified = false; 1321 1322 /** 1323 * @var question_attempt[] list of slot => {@link question_attempt}s that 1324 * have been added to the usage. 1325 */ 1326 protected $attemptsadded = array(); 1327 1328 /** 1329 * @var question_attempt[] list of slot => {@link question_attempt}s that 1330 * were already in the usage, and which have been modified. 1331 */ 1332 protected $attemptsmodified = array(); 1333 1334 /** 1335 * @var question_attempt[] list of slot => {@link question_attempt}s that 1336 * have been added to the usage. 1337 */ 1338 protected $attemptsdeleted = array(); 1339 1340 /** 1341 * @var array of array(question_attempt_step, question_attempt id, seq number) 1342 * of steps that have been added to question attempts in this usage. 1343 */ 1344 protected $stepsadded = array(); 1345 1346 /** 1347 * @var array of array(question_attempt_step, question_attempt id, seq number) 1348 * of steps that have been modified in their attempt. 1349 */ 1350 protected $stepsmodified = array(); 1351 1352 /** 1353 * @var question_attempt_step[] list of question_attempt_step.id => question_attempt_step of steps 1354 * that were previously stored in the database, but which are no longer required. 1355 */ 1356 protected $stepsdeleted = array(); 1357 1358 /** 1359 * @var array int slot => string name => question_attempt. 1360 */ 1361 protected $metadataadded = array(); 1362 1363 /** 1364 * @var array int slot => string name => question_attempt. 1365 */ 1366 protected $metadatamodified = array(); 1367 1368 /** 1369 * Constructor. 1370 * @param question_usage_by_activity $quba the usage to track. 1371 */ 1372 public function __construct(question_usage_by_activity $quba) { 1373 $this->quba = $quba; 1374 } 1375 1376 public function notify_modified() { 1377 $this->modified = true; 1378 } 1379 1380 public function notify_attempt_added(question_attempt $qa) { 1381 $this->attemptsadded[$qa->get_slot()] = $qa; 1382 } 1383 1384 public function notify_attempt_modified(question_attempt $qa) { 1385 $slot = $qa->get_slot(); 1386 if (!array_key_exists($slot, $this->attemptsadded)) { 1387 $this->attemptsmodified[$slot] = $qa; 1388 } 1389 } 1390 1391 public function notify_attempt_moved(question_attempt $qa, $oldslot) { 1392 $newslot = $qa->get_slot(); 1393 1394 if (array_key_exists($oldslot, $this->attemptsadded)) { 1395 unset($this->attemptsadded[$oldslot]); 1396 $this->attemptsadded[$newslot] = $qa; 1397 return; 1398 } 1399 1400 if (array_key_exists($oldslot, $this->attemptsmodified)) { 1401 unset($this->attemptsmodified[$oldslot]); 1402 } 1403 $this->attemptsmodified[$newslot] = $qa; 1404 1405 if (array_key_exists($oldslot, $this->metadataadded)) { 1406 $this->metadataadded[$newslot] = $this->metadataadded[$oldslot]; 1407 unset($this->metadataadded[$oldslot]); 1408 } 1409 if (array_key_exists($oldslot, $this->metadatamodified)) { 1410 $this->metadatamodified[$newslot] = $this->metadatamodified[$oldslot]; 1411 unset($this->metadatamodified[$oldslot]); 1412 } 1413 } 1414 1415 public function notify_step_added(question_attempt_step $step, question_attempt $qa, $seq) { 1416 if (array_key_exists($qa->get_slot(), $this->attemptsadded)) { 1417 return; 1418 } 1419 1420 if (($key = $this->is_step_added($step)) !== false) { 1421 return; 1422 } 1423 1424 if (($key = $this->is_step_modified($step)) !== false) { 1425 throw new coding_exception('Cannot add a step that has already been modified.'); 1426 } 1427 1428 if (($key = $this->is_step_deleted($step)) !== false) { 1429 unset($this->stepsdeleted[$step->get_id()]); 1430 $this->stepsmodified[] = array($step, $qa->get_database_id(), $seq); 1431 return; 1432 } 1433 1434 $stepid = $step->get_id(); 1435 if ($stepid) { 1436 if (array_key_exists($stepid, $this->stepsdeleted)) { 1437 unset($this->stepsdeleted[$stepid]); 1438 } 1439 $this->stepsmodified[] = array($step, $qa->get_database_id(), $seq); 1440 1441 } else { 1442 $this->stepsadded[] = array($step, $qa->get_database_id(), $seq); 1443 } 1444 } 1445 1446 public function notify_step_modified(question_attempt_step $step, question_attempt $qa, $seq) { 1447 if (array_key_exists($qa->get_slot(), $this->attemptsadded)) { 1448 return; 1449 } 1450 1451 if (($key = $this->is_step_added($step)) !== false) { 1452 return; 1453 } 1454 1455 if (($key = $this->is_step_deleted($step)) !== false) { 1456 throw new coding_exception('Cannot modify a step after it has been deleted.'); 1457 } 1458 1459 $stepid = $step->get_id(); 1460 if (empty($stepid)) { 1461 throw new coding_exception('Cannot modify a step that has never been stored in the database.'); 1462 } 1463 1464 $this->stepsmodified[] = array($step, $qa->get_database_id(), $seq); 1465 } 1466 1467 public function notify_step_deleted(question_attempt_step $step, question_attempt $qa) { 1468 if (array_key_exists($qa->get_slot(), $this->attemptsadded)) { 1469 return; 1470 } 1471 1472 if (($key = $this->is_step_added($step)) !== false) { 1473 unset($this->stepsadded[$key]); 1474 return; 1475 } 1476 1477 if (($key = $this->is_step_modified($step)) !== false) { 1478 unset($this->stepsmodified[$key]); 1479 } 1480 1481 $stepid = $step->get_id(); 1482 if (empty($stepid)) { 1483 return; // Was never in the database. 1484 } 1485 1486 $this->stepsdeleted[$stepid] = $step; 1487 } 1488 1489 public function notify_metadata_added(question_attempt $qa, $name) { 1490 if (array_key_exists($qa->get_slot(), $this->attemptsadded)) { 1491 return; 1492 } 1493 1494 if ($this->is_step_added($qa->get_step(0)) !== false) { 1495 return; 1496 } 1497 1498 if (isset($this->metadataadded[$qa->get_slot()][$name])) { 1499 return; 1500 } 1501 1502 $this->metadataadded[$qa->get_slot()][$name] = $qa; 1503 } 1504 1505 public function notify_metadata_modified(question_attempt $qa, $name) { 1506 if (array_key_exists($qa->get_slot(), $this->attemptsadded)) { 1507 return; 1508 } 1509 1510 if ($this->is_step_added($qa->get_step(0)) !== false) { 1511 return; 1512 } 1513 1514 if (isset($this->metadataadded[$qa->get_slot()][$name])) { 1515 return; 1516 } 1517 1518 if (isset($this->metadatamodified[$qa->get_slot()][$name])) { 1519 return; 1520 } 1521 1522 $this->metadatamodified[$qa->get_slot()][$name] = $qa; 1523 } 1524 1525 /** 1526 * Determine if a step is new. If so get its array key. 1527 * 1528 * @param question_attempt_step $step a step 1529 * @return int|false if the step is in the list of steps to be added, return 1530 * the key, otherwise return false. 1531 */ 1532 protected function is_step_added(question_attempt_step $step) { 1533 foreach ($this->stepsadded as $key => $data) { 1534 list($addedstep) = $data; 1535 if ($addedstep === $step) { 1536 return $key; 1537 } 1538 } 1539 return false; 1540 } 1541 1542 /** 1543 * Determine if a step is modified. If so get its array key. 1544 * 1545 * @param question_attempt_step $step a step 1546 * @return int|false if the step is in the list of steps to be modified, return 1547 * the key, otherwise return false. 1548 */ 1549 protected function is_step_modified(question_attempt_step $step) { 1550 foreach ($this->stepsmodified as $key => $data) { 1551 list($modifiedstep) = $data; 1552 if ($modifiedstep === $step) { 1553 return $key; 1554 } 1555 } 1556 return false; 1557 } 1558 1559 /** 1560 * @param question_attempt_step $step a step 1561 * @return bool whether the step is in the list of steps to be deleted. 1562 */ 1563 protected function is_step_deleted(question_attempt_step $step) { 1564 foreach ($this->stepsdeleted as $deletedstep) { 1565 if ($deletedstep === $step) { 1566 return true; 1567 } 1568 } 1569 return false; 1570 } 1571 1572 /** 1573 * Write all the changes we have recorded to the database. 1574 * @param question_engine_data_mapper $dm the mapper to use to update the database. 1575 */ 1576 public function save(question_engine_data_mapper $dm) { 1577 $dm->delete_steps(array_keys($this->stepsdeleted), $this->quba->get_owning_context()); 1578 1579 // Initially an array of array of question_attempt_step_objects. 1580 // Built as a nested array for efficiency, then flattened. 1581 $stepdata = array(); 1582 1583 foreach ($this->stepsmodified as $stepinfo) { 1584 list($step, $questionattemptid, $seq) = $stepinfo; 1585 $stepdata[] = $dm->update_question_attempt_step( 1586 $step, $questionattemptid, $seq, $this->quba->get_owning_context()); 1587 } 1588 1589 foreach ($this->stepsadded as $stepinfo) { 1590 list($step, $questionattemptid, $seq) = $stepinfo; 1591 $stepdata[] = $dm->insert_question_attempt_step( 1592 $step, $questionattemptid, $seq, $this->quba->get_owning_context()); 1593 } 1594 1595 foreach ($this->attemptsmodified as $qa) { 1596 $dm->update_question_attempt($qa); 1597 } 1598 1599 foreach ($this->attemptsadded as $qa) { 1600 $stepdata[] = $dm->insert_question_attempt( 1601 $qa, $this->quba->get_owning_context()); 1602 } 1603 1604 foreach ($this->metadataadded as $info) { 1605 $qa = reset($info); 1606 $stepdata[] = $dm->insert_question_attempt_metadata($qa, array_keys($info)); 1607 } 1608 1609 foreach ($this->metadatamodified as $info) { 1610 $qa = reset($info); 1611 $stepdata[] = $dm->update_question_attempt_metadata($qa, array_keys($info)); 1612 } 1613 1614 if ($this->modified) { 1615 $dm->update_questions_usage_by_activity($this->quba); 1616 } 1617 1618 $dm->insert_all_step_data($dm->combine_step_data($stepdata)); 1619 1620 $this->stepsdeleted = array(); 1621 $this->stepsmodified = array(); 1622 $this->stepsadded = array(); 1623 $this->attemptsdeleted = array(); 1624 $this->attemptsadded = array(); 1625 $this->attemptsmodified = array(); 1626 $this->modified = false; 1627 } 1628 } 1629 1630 1631 /** 1632 * The interface implemented by {@link question_file_saver} and {@link question_file_loader}. 1633 * 1634 * @copyright 2012 The Open University 1635 * @license http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later 1636 */ 1637 interface question_response_files { 1638 /** 1639 * Get the files that were submitted. 1640 * @return array of stored_files objects. 1641 */ 1642 public function get_files(); 1643 } 1644 1645 1646 /** 1647 * This class represents the promise to save some files from a particular draft 1648 * file area into a particular file area. It is used beause the necessary 1649 * information about what to save is to hand in the 1650 * {@link question_attempt::process_response_files()} method, but we don't know 1651 * if this question attempt will actually be saved in the database until later, 1652 * when the {@link question_engine_unit_of_work} is saved, if it is. 1653 * 1654 * @copyright 2011 The Open University 1655 * @license http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later 1656 */ 1657 class question_file_saver implements question_response_files { 1658 /** @var int the id of the draft file area to save files from. */ 1659 protected $draftitemid; 1660 /** @var string the owning component name. */ 1661 protected $component; 1662 /** @var string the file area name. */ 1663 protected $filearea; 1664 1665 /** 1666 * @var string the value to store in the question_attempt_step_data to 1667 * represent these files. 1668 */ 1669 protected $value = null; 1670 1671 /** 1672 * Constructor. 1673 * 1674 * @param int $draftitemid the draft area to save the files from. 1675 * @param string $component the component for the file area to save into. 1676 * @param string $filearea the name of the file area to save into. 1677 * @param string $text optional content containing file links. 1678 */ 1679 public function __construct($draftitemid, $component, $filearea, $text = null) { 1680 $this->draftitemid = $draftitemid; 1681 $this->component = $component; 1682 $this->filearea = $filearea; 1683 $this->value = $this->compute_value($draftitemid, $text); 1684 } 1685 1686 /** 1687 * Compute the value that should be stored in the question_attempt_step_data table. 1688 * 1689 * Contains a hash that (almost) uniquely encodes all the files. 1690 * 1691 * @param int $draftitemid the draft file area itemid. 1692 * @param string $text optional content containing file links. 1693 * @return string the value. 1694 */ 1695 protected function compute_value($draftitemid, $text) { 1696 global $USER; 1697 1698 $fs = get_file_storage(); 1699 $usercontext = context_user::instance($USER->id); 1700 1701 $files = $fs->get_area_files($usercontext->id, 'user', 'draft', 1702 $draftitemid, 'sortorder, filepath, filename', false); 1703 1704 $string = ''; 1705 foreach ($files as $file) { 1706 $string .= $file->get_filepath() . $file->get_filename() . '|' . 1707 $file->get_contenthash() . '|'; 1708 } 1709 $hash = md5($string); 1710 1711 if (is_null($text)) { 1712 if ($string) { 1713 return $hash; 1714 } else { 1715 return ''; 1716 } 1717 } 1718 1719 // We add the file hash so a simple string comparison will say if the 1720 // files have been changed. First strip off any existing file hash. 1721 if ($text !== '') { 1722 $text = preg_replace('/\s*<!-- File hash: \w+ -->\s*$/', '', $text); 1723 $text = file_rewrite_urls_to_pluginfile($text, $draftitemid); 1724 if ($string) { 1725 $text .= '<!-- File hash: ' . $hash . ' -->'; 1726 } 1727 } 1728 return $text; 1729 } 1730 1731 public function __toString() { 1732 return $this->value; 1733 } 1734 1735 /** 1736 * Actually save the files. 1737 * 1738 * @param integer $itemid the item id for the file area to save into. 1739 * @param context $context the context where the files should be saved. 1740 */ 1741 public function save_files($itemid, $context) { 1742 file_save_draft_area_files($this->draftitemid, $context->id, 1743 $this->component, $this->filearea, $itemid); 1744 } 1745 1746 /** 1747 * Get the files that were submitted. 1748 * @return array of stored_files objects. 1749 */ 1750 public function get_files() { 1751 global $USER; 1752 1753 $fs = get_file_storage(); 1754 $usercontext = context_user::instance($USER->id); 1755 1756 return $fs->get_area_files($usercontext->id, 'user', 'draft', 1757 $this->draftitemid, 'sortorder, filepath, filename', false); 1758 } 1759 } 1760 1761 1762 /** 1763 * This class is the mirror image of {@link question_file_saver}. It allows 1764 * files to be accessed again later (e.g. when re-grading) using that same 1765 * API as when doing the original grading. 1766 * 1767 * @copyright 2012 The Open University 1768 * @license http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later 1769 */ 1770 class question_file_loader implements question_response_files { 1771 /** @var question_attempt_step the step that these files belong to. */ 1772 protected $step; 1773 1774 /** @var string the field name for these files - which is used to construct the file area name. */ 1775 protected $name; 1776 1777 /** 1778 * @var string the value to stored in the question_attempt_step_data to 1779 * represent these files. 1780 */ 1781 protected $value; 1782 1783 /** @var int the context id that the files belong to. */ 1784 protected $contextid; 1785 1786 /** 1787 * Constuctor. 1788 * @param question_attempt_step $step the step that these files belong to. 1789 * @param string $name string the field name for these files - which is used to construct the file area name. 1790 * @param string $value the value to stored in the question_attempt_step_data to 1791 * represent these files. 1792 * @param int $contextid the context id that the files belong to. 1793 */ 1794 public function __construct(question_attempt_step $step, $name, $value, $contextid) { 1795 $this->step = $step; 1796 $this->name = $name; 1797 $this->value = $value; 1798 $this->contextid = $contextid; 1799 } 1800 1801 public function __toString() { 1802 return $this->value; 1803 } 1804 1805 /** 1806 * Get the files that were submitted. 1807 * @return array of stored_files objects. 1808 */ 1809 public function get_files() { 1810 return $this->step->get_qt_files($this->name, $this->contextid); 1811 } 1812 1813 /** 1814 * Copy these files into a draft area, and return the corresponding 1815 * {@link question_file_saver} that can save them again. 1816 * 1817 * This is used by {@link question_attempt::start_based_on()}, which is used 1818 * (for example) by the quizzes 'Each attempt builds on last' feature. 1819 * 1820 * @return question_file_saver that can re-save these files again. 1821 */ 1822 public function get_question_file_saver() { 1823 1824 // There are three possibilities here for what $value will look like: 1825 // 1) some HTML content followed by an MD5 hash in a HTML comment; 1826 // 2) a plain MD5 hash; 1827 // 3) or some real content, without any hash. 1828 // The problem is that 3) is ambiguous in the case where a student writes 1829 // a response that looks exactly like an MD5 hash. For attempts made now, 1830 // we avoid case 3) by always going for case 1) or 2) (except when the 1831 // response is blank. However, there may be case 3) data in the database 1832 // so we need to handle it as best we can. 1833 if (preg_match('/\s*<!-- File hash: [0-9a-zA-Z]{32} -->\s*$/', $this->value)) { 1834 $value = preg_replace('/\s*<!-- File hash: [0-9a-zA-Z]{32} -->\s*$/', '', $this->value); 1835 1836 } else if (preg_match('/^[0-9a-zA-Z]{32}$/', $this->value)) { 1837 $value = null; 1838 1839 } else { 1840 $value = $this->value; 1841 } 1842 1843 list($draftid, $text) = $this->step->prepare_response_files_draft_itemid_with_text( 1844 $this->name, $this->contextid, $value); 1845 return new question_file_saver($draftid, 'question', 'response_' . $this->name, $text); 1846 } 1847 } 1848 1849 1850 /** 1851 * This class represents a restriction on the set of question_usage ids to include 1852 * in a larger database query. Depending of the how you are going to restrict the 1853 * list of usages, construct an appropriate subclass. 1854 * 1855 * If $qubaids is an instance of this class, example usage might be 1856 * 1857 * SELECT qa.id, qa.maxmark 1858 * FROM $qubaids->from_question_attempts('qa') 1859 * WHERE $qubaids->where() AND qa.slot = 1 1860 * 1861 * @copyright 2010 The Open University 1862 * @license http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later 1863 */ 1864 abstract class qubaid_condition { 1865 1866 /** 1867 * Get the SQL fragment to go in a FROM clause. 1868 * 1869 * The SQL that needs to go in the FROM clause when trying 1870 * to select records from the 'question_attempts' table based on this 1871 * qubaid_condition. 1872 * 1873 * @param string $alias 1874 * @return string SQL fragment. 1875 */ 1876 public abstract function from_question_attempts($alias); 1877 1878 /** @return string the SQL that needs to go in the where clause. */ 1879 public abstract function where(); 1880 1881 /** 1882 * @return array the params needed by a query that uses 1883 * {@link from_question_attempts()} and {@link where()}. 1884 */ 1885 public abstract function from_where_params(); 1886 1887 /** 1888 * @return string SQL that can use used in a WHERE qubaid IN (...) query. 1889 * This method returns the "IN (...)" part. 1890 */ 1891 public abstract function usage_id_in(); 1892 1893 /** 1894 * @return array the params needed by a query that uses {@link usage_id_in()}. 1895 */ 1896 public abstract function usage_id_in_params(); 1897 1898 /** 1899 * @return string 40-character hash code that uniquely identifies the combination of properties and class name of this qubaid 1900 * condition. 1901 */ 1902 public function get_hash_code() { 1903 return sha1(serialize($this)); 1904 } 1905 } 1906 1907 1908 /** 1909 * This class represents a restriction on the set of question_usage ids to include 1910 * in a larger database query based on an explicit list of ids. 1911 * 1912 * @copyright 2010 The Open University 1913 * @license http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later 1914 */ 1915 class qubaid_list extends qubaid_condition { 1916 /** @var array of ids. */ 1917 protected $qubaids; 1918 protected $columntotest = null; 1919 protected $params; 1920 1921 /** 1922 * Constructor. 1923 * @param array $qubaids of question usage ids. 1924 */ 1925 public function __construct(array $qubaids) { 1926 $this->qubaids = $qubaids; 1927 } 1928 1929 public function from_question_attempts($alias) { 1930 $this->columntotest = $alias . '.questionusageid'; 1931 return '{question_attempts} ' . $alias; 1932 } 1933 1934 public function where() { 1935 if (is_null($this->columntotest)) { 1936 throw new coding_exception('Must call from_question_attempts before where().'); 1937 } 1938 if (empty($this->qubaids)) { 1939 $this->params = array(); 1940 return '1 = 0'; 1941 } 1942 1943 return $this->columntotest . ' ' . $this->usage_id_in(); 1944 } 1945 1946 public function from_where_params() { 1947 return $this->params; 1948 } 1949 1950 public function usage_id_in() { 1951 global $DB; 1952 1953 if (empty($this->qubaids)) { 1954 $this->params = array(); 1955 return '= 0'; 1956 } 1957 list($where, $this->params) = $DB->get_in_or_equal( 1958 $this->qubaids, SQL_PARAMS_NAMED, 'qubaid'); 1959 return $where; 1960 } 1961 1962 public function usage_id_in_params() { 1963 return $this->params; 1964 } 1965 } 1966 1967 1968 /** 1969 * This class represents a restriction on the set of question_usage ids to include 1970 * in a larger database query based on JOINing to some other tables. 1971 * 1972 * The general form of the query is something like 1973 * 1974 * SELECT qa.id, qa.maxmark 1975 * FROM $from 1976 * JOIN {question_attempts} qa ON qa.questionusageid = $usageidcolumn 1977 * WHERE $where AND qa.slot = 1 1978 * 1979 * where $from, $usageidcolumn and $where are the arguments to the constructor. 1980 * 1981 * @copyright 2010 The Open University 1982 * @license http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later 1983 */ 1984 class qubaid_join extends qubaid_condition { 1985 public $from; 1986 public $usageidcolumn; 1987 public $where; 1988 public $params; 1989 1990 /** 1991 * Constructor. The meaning of the arguments is explained in the class comment. 1992 * @param string $from SQL fragemnt to go in the FROM clause. 1993 * @param string $usageidcolumn the column in $from that should be 1994 * made equal to the usageid column in the JOIN clause. 1995 * @param string $where SQL fragment to go in the where clause. 1996 * @param array $params required by the SQL. You must use named parameters. 1997 */ 1998 public function __construct($from, $usageidcolumn, $where = '', $params = array()) { 1999 $this->from = $from; 2000 $this->usageidcolumn = $usageidcolumn; 2001 $this->params = $params; 2002 if (empty($where)) { 2003 $where = '1 = 1'; 2004 } 2005 $this->where = $where; 2006 } 2007 2008 public function from_question_attempts($alias) { 2009 return "{$this->from} 2010 JOIN {question_attempts} {$alias} ON " . 2011 "{$alias}.questionusageid = $this->usageidcolumn"; 2012 } 2013 2014 public function where() { 2015 return $this->where; 2016 } 2017 2018 public function from_where_params() { 2019 return $this->params; 2020 } 2021 2022 public function usage_id_in() { 2023 return "IN (SELECT {$this->usageidcolumn} FROM {$this->from} WHERE {$this->where})"; 2024 } 2025 2026 public function usage_id_in_params() { 2027 return $this->params; 2028 } 2029 }
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