cohort/externallib.php

   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  * External cohort API
  19  *
  20  * @package    core_cohort
  21  * @category   external
  22  * @copyright  MediaTouch 2000 srl
  23  * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
  24  */
  25
  26 require_once("$CFG->libdir/externallib.php");
  27
  28 class core_cohort_external extends external_api {
  29
  30     /**
  31      * Returns description of method parameters
  32      *
  33      * @return external_function_parameters
  34      * @since Moodle 2.5
  35      */
  36     public static function create_cohorts_parameters() {
  37         return new external_function_parameters(
  38             array(
  39                 'cohorts' => new external_multiple_structure(
  40                     new external_single_structure(
  41                         array(
  42                             'categorytype' => new external_single_structure(
  43                                 array(
  44                                     'type' => new external_value(PARAM_TEXT, 'the name of the field: id (numeric value
  45                                         of course category id) or idnumber (alphanumeric value of idnumber course category)
  46                                         or system (value ignored)'),
  47                                     'value' => new external_value(PARAM_RAW, 'the value of the categorytype')
  48                                 )
  49                             ),
  50                             'name' => new external_value(PARAM_RAW, 'cohort name'),
  51                             'idnumber' => new external_value(PARAM_RAW, 'cohort idnumber'),
  52                             'description' => new external_value(PARAM_RAW, 'cohort description', VALUE_OPTIONAL),
  53                             'descriptionformat' => new external_format_value('description', VALUE_DEFAULT),
  54                             'visible' => new external_value(PARAM_BOOL, 'cohort visible', VALUE_OPTIONAL, true),
  55                         )
  56                     )
  57                 )
  58             )
  59         );
  60     }
  61
  62     /**
  63      * Create one or more cohorts
  64      *
  65      * @param array $cohorts An array of cohorts to create.
  66      * @return array An array of arrays
  67      * @since Moodle 2.5
  68      */
  69     public static function create_cohorts($cohorts) {
  70         global $CFG, $DB;
  71         require_once("$CFG->dirroot/cohort/lib.php");
  72
  73         $params = self::validate_parameters(self::create_cohorts_parameters(), array('cohorts' => $cohorts));
  74
  75         $transaction = $DB->start_delegated_transaction();
  76
  77         $syscontext = context_system::instance();
  78         $cohortids = array();
  79
  80         foreach ($params['cohorts'] as $cohort) {
  81             $cohort = (object)$cohort;
  82
  83             // Category type (context id).
  84             $categorytype = $cohort->categorytype;
  85             if (!in_array($categorytype['type'], array('idnumber', 'id', 'system'))) {
  86                 throw new invalid_parameter_exception('category type must be id, idnumber or system:' . $categorytype['type']);
  87             }
  88             if ($categorytype['type'] === 'system') {
  89                 $cohort->contextid = $syscontext->id;
  90             } else if ($catid = $DB->get_field('course_categories', 'id', array($categorytype['type'] => $categorytype['value']))) {
  91                 $catcontext = context_coursecat::instance($catid);
  92                 $cohort->contextid = $catcontext->id;
  93             } else {
  94                 throw new invalid_parameter_exception('category not exists: category '
  95                     .$categorytype['type'].' = '.$categorytype['value']);
  96             }
  97             // Make sure that the idnumber doesn't already exist.
  98             if ($DB->record_exists('cohort', array('idnumber' => $cohort->idnumber))) {
  99                 throw new invalid_parameter_exception('record already exists: idnumber='.$cohort->idnumber);
 100             }
 101             $context = context::instance_by_id($cohort->contextid, MUST_EXIST);
 102             if ($context->contextlevel != CONTEXT_COURSECAT and $context->contextlevel != CONTEXT_SYSTEM) {
 103                 throw new invalid_parameter_exception('Invalid context');
 104             }
 105             self::validate_context($context);
 106             require_capability('moodle/cohort:manage', $context);
 107
 108             // Validate format.
 109             $cohort->descriptionformat = external_validate_format($cohort->descriptionformat);
 110             $cohort->id = cohort_add_cohort($cohort);
 111
 112             list($cohort->description, $cohort->descriptionformat) =
 113                 external_format_text($cohort->description, $cohort->descriptionformat,
 114                         $context->id, 'cohort', 'description', $cohort->id);
 115             $cohortids[] = (array)$cohort;
 116         }
 117         $transaction->allow_commit();
 118
 119         return $cohortids;
 120     }
 121
 122     /**
 123      * Returns description of method result value
 124      *
 125      * @return external_description
 126      * @since Moodle 2.5
 127      */
 128     public static function create_cohorts_returns() {
 129         return new external_multiple_structure(
 130             new external_single_structure(
 131                 array(
 132                     'id' => new external_value(PARAM_INT, 'cohort id'),
 133                     'name' => new external_value(PARAM_RAW, 'cohort name'),
 134                     'idnumber' => new external_value(PARAM_RAW, 'cohort idnumber'),
 135                     'description' => new external_value(PARAM_RAW, 'cohort description'),
 136                     'descriptionformat' => new external_format_value('description'),
 137                     'visible' => new external_value(PARAM_BOOL, 'cohort visible'),
 138                 )
 139             )
 140         );
 141     }
 142
 143     /**
 144      * Returns description of method parameters
 145      *
 146      * @return external_function_parameters
 147      * @since Moodle 2.5
 148      */
 149     public static function delete_cohorts_parameters() {
 150         return new external_function_parameters(
 151             array(
 152                 'cohortids' => new external_multiple_structure(new external_value(PARAM_INT, 'cohort ID')),
 153             )
 154         );
 155     }
 156
 157     /**
 158      * Delete cohorts
 159      *
 160      * @param array $cohortids
 161      * @return null
 162      * @since Moodle 2.5
 163      */
 164     public static function delete_cohorts($cohortids) {
 165         global $CFG, $DB;
 166         require_once("$CFG->dirroot/cohort/lib.php");
 167
 168         $params = self::validate_parameters(self::delete_cohorts_parameters(), array('cohortids' => $cohortids));
 169
 170         $transaction = $DB->start_delegated_transaction();
 171
 172         foreach ($params['cohortids'] as $cohortid) {
 173             // Validate params.
 174             $cohortid = validate_param($cohortid, PARAM_INT);
 175             $cohort = $DB->get_record('cohort', array('id' => $cohortid), '*', MUST_EXIST);
 176
 177             // Now security checks.
 178             $context = context::instance_by_id($cohort->contextid, MUST_EXIST);
 179             if ($context->contextlevel != CONTEXT_COURSECAT and $context->contextlevel != CONTEXT_SYSTEM) {
 180                 throw new invalid_parameter_exception('Invalid context');
 181             }
 182             self::validate_context($context);
 183             require_capability('moodle/cohort:manage', $context);
 184             cohort_delete_cohort($cohort);
 185         }
 186         $transaction->allow_commit();
 187
 188         return null;
 189     }
 190
 191     /**
 192      * Returns description of method result value
 193      *
 194      * @return null
 195      * @since Moodle 2.5
 196      */
 197     public static function delete_cohorts_returns() {
 198         return null;
 199     }
 200
 201     /**
 202      * Returns description of method parameters
 203      *
 204      * @return external_function_parameters
 205      * @since Moodle 2.5
 206      */
 207     public static function get_cohorts_parameters() {
 208         return new external_function_parameters(
 209             array(
 210                 'cohortids' => new external_multiple_structure(new external_value(PARAM_INT, 'Cohort ID')
 211                     , 'List of cohort id. A cohort id is an integer.', VALUE_DEFAULT, array()),
 212             )
 213         );
 214     }
 215
 216     /**
 217      * Get cohorts definition specified by ids
 218      *
 219      * @param array $cohortids array of cohort ids
 220      * @return array of cohort objects (id, courseid, name)
 221      * @since Moodle 2.5
 222      */
 223     public static function get_cohorts($cohortids = array()) {
 224         global $DB;
 225
 226         $params = self::validate_parameters(self::get_cohorts_parameters(), array('cohortids' => $cohortids));
 227
 228         if (empty($cohortids)) {
 229             $cohorts = $DB->get_records('cohort');
 230         } else {
 231             $cohorts = $DB->get_records_list('cohort', 'id', $params['cohortids']);
 232         }
 233
 234         $cohortsinfo = array();
 235         foreach ($cohorts as $cohort) {
 236             // Now security checks.
 237             $context = context::instance_by_id($cohort->contextid, MUST_EXIST);
 238             if ($context->contextlevel != CONTEXT_COURSECAT and $context->contextlevel != CONTEXT_SYSTEM) {
 239                 throw new invalid_parameter_exception('Invalid context');
 240             }
 241             self::validate_context($context);
 242             if (!has_any_capability(array('moodle/cohort:manage', 'moodle/cohort:view'), $context)) {
 243                 throw new required_capability_exception($context, 'moodle/cohort:view', 'nopermissions', '');
 244             }
 245
 246             list($cohort->description, $cohort->descriptionformat) =
 247                 external_format_text($cohort->description, $cohort->descriptionformat,
 248                         $context->id, 'cohort', 'description', $cohort->id);
 249
 250             $cohortsinfo[] = (array) $cohort;
 251         }
 252         return $cohortsinfo;
 253     }
 254
 255
 256     /**
 257      * Returns description of method result value
 258      *
 259      * @return external_description
 260      * @since Moodle 2.5
 261      */
 262     public static function get_cohorts_returns() {
 263         return new external_multiple_structure(
 264             new external_single_structure(
 265                 array(
 266                     'id' => new external_value(PARAM_INT, 'ID of the cohort'),
 267                     'name' => new external_value(PARAM_RAW, 'cohort name'),
 268                     'idnumber' => new external_value(PARAM_RAW, 'cohort idnumber'),
 269                     'description' => new external_value(PARAM_RAW, 'cohort description'),
 270                     'descriptionformat' => new external_format_value('description'),
 271                     'visible' => new external_value(PARAM_BOOL, 'cohort visible'),
 272                 )
 273             )
 274         );
 275     }
 276
 277     /**
 278      * Returns description of method parameters
 279      *
 280      * @return external_function_parameters
 281      * @since Moodle 2.5
 282      */
 283     public static function update_cohorts_parameters() {
 284         return new external_function_parameters(
 285             array(
 286                 'cohorts' => new external_multiple_structure(
 287                     new external_single_structure(
 288                         array(
 289                             'id' => new external_value(PARAM_INT, 'ID of the cohort'),
 290                             'categorytype' => new external_single_structure(
 291                                 array(
 292                                     'type' => new external_value(PARAM_TEXT, 'the name of the field: id (numeric value
 293                                         of course category id) or idnumber (alphanumeric value of idnumber course category)
 294                                         or system (value ignored)'),
 295                                     'value' => new external_value(PARAM_RAW, 'the value of the categorytype')
 296                                 )
 297                             ),
 298                             'name' => new external_value(PARAM_RAW, 'cohort name'),
 299                             'idnumber' => new external_value(PARAM_RAW, 'cohort idnumber'),
 300                             'description' => new external_value(PARAM_RAW, 'cohort description', VALUE_OPTIONAL),
 301                             'descriptionformat' => new external_format_value('description', VALUE_DEFAULT),
 302                             'visible' => new external_value(PARAM_BOOL, 'cohort visible', VALUE_OPTIONAL),
 303                         )
 304                     )
 305                 )
 306             )
 307         );
 308     }
 309
 310     /**
 311      * Update cohorts
 312      *
 313      * @param array $cohorts
 314      * @return null
 315      * @since Moodle 2.5
 316      */
 317     public static function update_cohorts($cohorts) {
 318         global $CFG, $DB;
 319         require_once("$CFG->dirroot/cohort/lib.php");
 320
 321         $params = self::validate_parameters(self::update_cohorts_parameters(), array('cohorts' => $cohorts));
 322
 323         $transaction = $DB->start_delegated_transaction();
 324         $syscontext = context_system::instance();
 325
 326         foreach ($params['cohorts'] as $cohort) {
 327             $cohort = (object) $cohort;
 328
 329             if (trim($cohort->name) == '') {
 330                 throw new invalid_parameter_exception('Invalid cohort name');
 331             }
 332
 333             $oldcohort = $DB->get_record('cohort', array('id' => $cohort->id), '*', MUST_EXIST);
 334             $oldcontext = context::instance_by_id($oldcohort->contextid, MUST_EXIST);
 335             require_capability('moodle/cohort:manage', $oldcontext);
 336
 337             // Category type (context id).
 338             $categorytype = $cohort->categorytype;
 339             if (!in_array($categorytype['type'], array('idnumber', 'id', 'system'))) {
 340                 throw new invalid_parameter_exception('category type must be id, idnumber or system:' . $categorytype['type']);
 341             }
 342             if ($categorytype['type'] === 'system') {
 343                 $cohort->contextid = $syscontext->id;
 344             } else if ($catid = $DB->get_field('course_categories', 'id', array($categorytype['type'] => $categorytype['value']))) {
 345                 $cohort->contextid = $DB->get_field('context', 'id', array('instanceid' => $catid,
 346                     'contextlevel' => CONTEXT_COURSECAT));
 347             } else {
 348                 throw new invalid_parameter_exception('category not exists: category='.$categorytype['value']);
 349             }
 350
 351             if ($cohort->contextid != $oldcohort->contextid) {
 352                 $context = context::instance_by_id($cohort->contextid, MUST_EXIST);
 353                 if ($context->contextlevel != CONTEXT_COURSECAT and $context->contextlevel != CONTEXT_SYSTEM) {
 354                     throw new invalid_parameter_exception('Invalid context');
 355                 }
 356
 357                 self::validate_context($context);
 358                 require_capability('moodle/cohort:manage', $context);
 359             }
 360
 361             if (!empty($cohort->description)) {
 362                 $cohort->descriptionformat = external_validate_format($cohort->descriptionformat);
 363             }
 364
 365             cohort_update_cohort($cohort);
 366         }
 367
 368         $transaction->allow_commit();
 369
 370         return null;
 371     }
 372
 373     /**
 374      * Returns description of method result value
 375      *
 376      * @return null
 377      * @since Moodle 2.5
 378      */
 379     public static function update_cohorts_returns() {
 380         return null;
 381     }
 382
 383     /**
 384      * Returns description of method parameters
 385      *
 386      * @return external_function_parameters
 387      * @since Moodle 2.5
 388      */
 389     public static function add_cohort_members_parameters() {
 390         return new external_function_parameters (
 391             array(
 392                 'members' => new external_multiple_structure (
 393                     new external_single_structure (
 394                         array (
 395                             'cohorttype' => new external_single_structure (
 396                                 array(
 397                                     'type' => new external_value(PARAM_ALPHANUMEXT, 'The name of the field: id
 398                                         (numeric value of cohortid) or idnumber (alphanumeric value of idnumber) '),
 399                                     'value' => new external_value(PARAM_RAW, 'The value of the cohort')
 400                                 )
 401                             ),
 402                             'usertype' => new external_single_structure (
 403                                 array(
 404                                     'type' => new external_value(PARAM_ALPHANUMEXT, 'The name of the field: id
 405                                         (numeric value of id) or username (alphanumeric value of username) '),
 406                                     'value' => new external_value(PARAM_RAW, 'The value of the cohort')
 407                                 )
 408                             )
 409                         )
 410                     )
 411                 )
 412             )
 413         );
 414     }
 415
 416     /**
 417      * Add cohort members
 418      *
 419      * @param array $members of arrays with keys userid, cohortid
 420      * @since Moodle 2.5
 421      */
 422     public static function add_cohort_members($members) {
 423         global $CFG, $DB;
 424         require_once($CFG->dirroot."/cohort/lib.php");
 425
 426         $params = self::validate_parameters(self::add_cohort_members_parameters(), array('members' => $members));
 427
 428         $transaction = $DB->start_delegated_transaction();
 429         $warnings = array();
 430         foreach ($params['members'] as $member) {
 431             // Cohort parameters.
 432             $cohorttype = $member['cohorttype'];
 433             $cohortparam = array($cohorttype['type'] => $cohorttype['value']);
 434             // User parameters.
 435             $usertype = $member['usertype'];
 436             $userparam = array($usertype['type'] => $usertype['value']);
 437             try {
 438                 // Check parameters.
 439                 if ($cohorttype['type'] != 'id' && $cohorttype['type'] != 'idnumber') {
 440                     $warning = array();
 441                     $warning['warningcode'] = '1';
 442                     $warning['message'] = 'invalid parameter: cohortype='.$cohorttype['type'];
 443                     $warnings[] = $warning;
 444                     continue;
 445                 }
 446                 if ($usertype['type'] != 'id' && $usertype['type'] != 'username') {
 447                     $warning = array();
 448                     $warning['warningcode'] = '1';
 449                     $warning['message'] = 'invalid parameter: usertype='.$usertype['type'];
 450                     $warnings[] = $warning;
 451                     continue;
 452                 }
 453                 // Extract parameters.
 454                 if (!$cohortid = $DB->get_field('cohort', 'id', $cohortparam)) {
 455                     $warning = array();
 456                     $warning['warningcode'] = '2';
 457                     $warning['message'] = 'cohort '.$cohorttype['type'].'='.$cohorttype['value'].' not exists';
 458                     $warnings[] = $warning;
 459                     continue;
 460                 }
 461                 if (!$userid = $DB->get_field('user', 'id', array_merge($userparam, array('deleted' => 0,
 462                     'mnethostid' => $CFG->mnet_localhost_id)))) {
 463                     $warning = array();
 464                     $warning['warningcode'] = '2';
 465                     $warning['message'] = 'user '.$usertype['type'].'='.$usertype['value'].' not exists';
 466                     $warnings[] = $warning;
 467                     continue;
 468                 }
 469                 if ($DB->record_exists('cohort_members', array('cohortid' => $cohortid, 'userid' => $userid))) {
 470                     $warning = array();
 471                     $warning['warningcode'] = '3';
 472                     $warning['message'] = 'record already exists: cohort('.$cohorttype['type'].'='.$cohorttype['value'].' '.
 473                         $usertype['type'].'='.$usertype['value'].')';
 474                     $warnings[] = $warning;
 475                     continue;
 476                 }
 477                 $cohort = $DB->get_record('cohort', array('id'=>$cohortid), '*', MUST_EXIST);
 478                 $context = context::instance_by_id($cohort->contextid, MUST_EXIST);
 479                 if ($context->contextlevel != CONTEXT_COURSECAT and $context->contextlevel != CONTEXT_SYSTEM) {
 480                     $warning = array();
 481                     $warning['warningcode'] = '1';
 482                     $warning['message'] = 'Invalid context: '.$context->contextlevel;
 483                     $warnings[] = $warning;
 484                     continue;
 485                 }
 486                 self::validate_context($context);
 487             } catch (Exception $e) {
 488                 throw new moodle_exception('Error', 'cohort', '', $e->getMessage());
 489             }
 490             if (!has_any_capability(array('moodle/cohort:manage', 'moodle/cohort:assign'), $context)) {
 491                 throw new required_capability_exception($context, 'moodle/cohort:assign', 'nopermissions', '');
 492             }
 493             cohort_add_member($cohortid, $userid);
 494         }
 495         $transaction->allow_commit();
 496         // Return.
 497         $result = array();
 498         $result['warnings'] = $warnings;
 499         return $result;
 500     }
 501
 502     /**
 503      * Returns description of method result value
 504      *
 505      * @return null
 506      * @since Moodle 2.5
 507      */
 508     public static function add_cohort_members_returns() {
 509         return new external_single_structure(
 510             array(
 511                 'warnings' => new external_warnings()
 512             )
 513         );
 514     }
 515
 516     /**
 517      * Returns description of method parameters
 518      *
 519      * @return external_function_parameters
 520      * @since Moodle 2.5
 521      */
 522     public static function delete_cohort_members_parameters() {
 523         return new external_function_parameters(
 524             array(
 525                 'members' => new external_multiple_structure(
 526                     new external_single_structure(
 527                         array(
 528                             'cohortid' => new external_value(PARAM_INT, 'cohort record id'),
 529                             'userid' => new external_value(PARAM_INT, 'user id'),
 530                         )
 531                     )
 532                 )
 533             )
 534         );
 535     }
 536
 537     /**
 538      * Delete cohort members
 539      *
 540      * @param array $members of arrays with keys userid, cohortid
 541      * @since Moodle 2.5
 542      */
 543     public static function delete_cohort_members($members) {
 544         global $CFG, $DB;
 545         require_once("$CFG->dirroot/cohort/lib.php");
 546
 547         // Validate parameters.
 548         $params = self::validate_parameters(self::delete_cohort_members_parameters(), array('members' => $members));
 549
 550         $transaction = $DB->start_delegated_transaction();
 551
 552         foreach ($params['members'] as $member) {
 553             $cohortid = $member['cohortid'];
 554             $userid = $member['userid'];
 555
 556             $cohort = $DB->get_record('cohort', array('id' => $cohortid), '*', MUST_EXIST);
 557             $user = $DB->get_record('user', array('id' => $userid, 'deleted' => 0, 'mnethostid' => $CFG->mnet_localhost_id),
 558                 '*', MUST_EXIST);
 559
 560             // Now security checks.
 561             $context = context::instance_by_id($cohort->contextid, MUST_EXIST);
 562             if ($context->contextlevel != CONTEXT_COURSECAT and $context->contextlevel != CONTEXT_SYSTEM) {
 563                 throw new invalid_parameter_exception('Invalid context');
 564             }
 565             self::validate_context($context);
 566             if (!has_any_capability(array('moodle/cohort:manage', 'moodle/cohort:assign'), $context)) {
 567                 throw new required_capability_exception($context, 'moodle/cohort:assign', 'nopermissions', '');
 568             }
 569
 570             cohort_remove_member($cohort->id, $user->id);
 571         }
 572         $transaction->allow_commit();
 573     }
 574
 575     /**
 576      * Returns description of method result value
 577      *
 578      * @return null
 579      * @since Moodle 2.5
 580      */
 581     public static function delete_cohort_members_returns() {
 582         return null;
 583     }
 584
 585     /**
 586      * Returns description of method parameters
 587      *
 588      * @return external_function_parameters
 589      * @since Moodle 2.5
 590      */
 591     public static function get_cohort_members_parameters() {
 592         return new external_function_parameters(
 593             array(
 594                 'cohortids' => new external_multiple_structure(new external_value(PARAM_INT, 'Cohort ID')),
 595             )
 596         );
 597     }
 598
 599     /**
 600      * Return all members for a cohort
 601      *
 602      * @param array $cohortids array of cohort ids
 603      * @return array with cohort id keys containing arrays of user ids
 604      * @since Moodle 2.5
 605      */
 606     public static function get_cohort_members($cohortids) {
 607         global $DB;
 608         $params = self::validate_parameters(self::get_cohort_members_parameters(), array('cohortids' => $cohortids));
 609
 610         $members = array();
 611
 612         foreach ($params['cohortids'] as $cohortid) {
 613             // Validate params.
 614             $cohort = $DB->get_record('cohort', array('id' => $cohortid), '*', MUST_EXIST);
 615             // Now security checks.
 616             $context = context::instance_by_id($cohort->contextid, MUST_EXIST);
 617             if ($context->contextlevel != CONTEXT_COURSECAT and $context->contextlevel != CONTEXT_SYSTEM) {
 618                 throw new invalid_parameter_exception('Invalid context');
 619             }
 620             self::validate_context($context);
 621             if (!has_any_capability(array('moodle/cohort:manage', 'moodle/cohort:view'), $context)) {
 622                 throw new required_capability_exception($context, 'moodle/cohort:view', 'nopermissions', '');
 623             }
 624
 625             $cohortmembers = $DB->get_records_sql("SELECT u.id FROM {user} u, {cohort_members} cm
 626                 WHERE u.id = cm.userid AND cm.cohortid = ?
 627                 ORDER BY lastname ASC, firstname ASC", array($cohort->id));
 628             $members[] = array('cohortid' => $cohortid, 'userids' => array_keys($cohortmembers));
 629         }
 630         return $members;
 631     }
 632
 633     /**
 634      * Returns description of method result value
 635      *
 636      * @return external_description
 637      * @since Moodle 2.5
 638      */
 639     public static function get_cohort_members_returns() {
 640         return new external_multiple_structure(
 641             new external_single_structure(
 642                 array(
 643                     'cohortid' => new external_value(PARAM_INT, 'cohort record id'),
 644                     'userids' => new external_multiple_structure(new external_value(PARAM_INT, 'user id')),
 645                 )
 646             )
 647         );
 648     }
 649 }