mod/hotpot/report.php

   1 <?PHP  // $Id$
   2
   3 // This script uses installed report plugins to print quiz reports
   4
   5     require_once("../../config.php");
   6     require_once("lib.php");
   7
   8     $id = optional_param('id', 0, PARAM_INT); // Course Module ID, or
   9     $hp = optional_param('hp', 0, PARAM_INT); // hotpot ID
  10
  11     if ($id) {
  12         if (! $cm = get_coursemodule_from_id('hotpot', $id)) {
  13             error("Course Module ID was incorrect");
  14         }
  15         if (! $course = get_record("course", "id", $cm->course)) {
  16             error("Course is misconfigured");
  17         }
  18         if (! $hotpot = get_record("hotpot", "id", $cm->instance)) {
  19             error("Course module is incorrect");
  20         }
  21
  22     } else {
  23         if (! $hotpot = get_record("hotpot", "id", $hp)) {
  24             error("Course module is incorrect");
  25         }
  26         if (! $course = get_record("course", "id", $hotpot->course)) {
  27             error("Course is misconfigured");
  28         }
  29         if (! $cm = get_coursemodule_from_instance("hotpot", $hotpot->id, $course->id)) {
  30             error("Course Module ID was incorrect");
  31         }
  32     }
  33
  34     // get the roles context for this course
  35     $sitecontext = get_context_instance(CONTEXT_SYSTEM, SITEID);
  36     $modulecontext = get_context_instance(CONTEXT_MODULE, $cm->id);
  37
  38     // set homeurl of couse (for error messages)
  39     $course_homeurl = "$CFG->wwwroot/course/view.php?id=$course->id";
  40
  41     require_login($course);
  42
  43     // check user can access this hotpot activity
  44     if (!hotpot_is_visible($cm)) {
  45         print_error("activityiscurrentlyhidden");
  46     }
  47
  48     // get report mode
  49     if (has_capability('mod/hotpot:viewreport',$modulecontext)) {
  50         $mode = optional_param('mode', 'overview', PARAM_ALPHA);
  51     } else {
  52         // ordinary students have no choice
  53         $mode = 'overview';
  54     }
  55
  56     // assemble array of form data
  57     $formdata = array(
  58         'mode' => $mode,
  59         'reportusers'      => has_capability('mod/hotpot:viewreport',$modulecontext) ? optional_param('reportusers', get_user_preferences('hotpot_reportusers', 'allusers'), PARAM_ALPHANUM) : 'this',
  60         'reportattempts'   => optional_param('reportattempts', get_user_preferences('hotpot_reportattempts', 'all'), PARAM_ALPHA),
  61         'reportformat'     => optional_param('reportformat', 'htm', PARAM_ALPHA),
  62         'reportshowlegend' => optional_param('reportshowlegend', get_user_preferences('hotpot_reportshowlegend', '0'), PARAM_INT),
  63         'reportencoding'   => optional_param('reportencoding', get_user_preferences('hotpot_reportencoding', ''), PARAM_ALPHANUM),
  64         'reportwrapdata'   => optional_param('reportwrapdata', get_user_preferences('hotpot_reportwrapdata', '1'), PARAM_INT),
  65     );
  66
  67     foreach ($formdata as $name=>$value) {
  68         set_user_preference("hotpot_$name", $value);
  69     }
  70
  71 /// Start the report
  72
  73     add_to_log($course->id, "hotpot", "report", "report.php?id=$cm->id&mode=$mode", "$hotpot->id", "$cm->id");
  74
  75     // print page header. if required
  76     if ($formdata['reportformat']=='htm') {
  77         hotpot_print_report_heading($course, $cm, $hotpot, $mode);
  78         if (has_capability('mod/hotpot:viewreport',$modulecontext)) {
  79             hotpot_print_report_selector($course, $hotpot, $formdata);
  80         }
  81     }
  82
  83     // delete selected attempts, if any
  84     if (has_capability('mod/hotpot:deleteattempt',$modulecontext)) {
  85         $del = optional_param('del', '', PARAM_ALPHA);
  86         hotpot_delete_selected_attempts($hotpot, $del);
  87     }
  88
  89     // check for groups
  90     if (preg_match('/^group(\d*)$/', $formdata['reportusers'], $matches)) {
  91         $formdata['reportusers'] = 'group';
  92         $formdata['reportgroupid'] = 0;
  93         // validate groupid
  94         if ($groups = groups_get_all_groups($course->id)) {
  95             if (isset($groups[$matches[1]])) {
  96                 $formdata['reportgroupid'] = $matches[1];
  97             }
  98         }
  99     }
 100
 101     $user_ids = '';
 102     $users = array();
 103
 104     switch ($formdata['reportusers']) {
 105
 106         case 'allusers':
 107             // anyone who has ever attempted this hotpot
 108             if ($records = get_records_select('hotpot_attempts', "hotpot=$hotpot->id", '', 'id,userid')) {
 109                 foreach ($records as $record) {
 110                     $users[$record->userid] = 0; // "0" means user is NOT currently allowed to attempt this HotPot
 111                 }
 112                 unset($records);
 113             }
 114             break;
 115
 116         case 'group':
 117             // group members
 118             if ($members = groups_get_members($formdata['reportgroupid'])) {
 119                 foreach ($members as $memberid=>$unused) {
 120                     $users[$memberid] = 1; // "1" signifies currently recognized participant
 121                 }
 122             }
 123             break;
 124
 125         case 'allparticipants':
 126             // anyone currently allowed to attempt this HotPot
 127             if ($records = get_users_by_capability($modulecontext, 'mod/hotpot:attempt', 'u.id,u.id', 'u.id')) {
 128                 foreach ($records as $record) {
 129                     $users[$record->id] = 1; // "1" means user is allowed to do this HotPot
 130                 }
 131                 unset($records);
 132             }
 133             break;
 134
 135         case 'existingstudents':
 136             // anyone currently allowed to attempt this HotPot who is not a teacher
 137             $teachers = get_users_by_capability($modulecontext, 'mod/hotpot:viewreport', 'u.id,u.id', 'u.id');
 138             if ($records = get_users_by_capability($modulecontext, 'mod/hotpot:attempt', 'u.id,u.id', 'u.id')) {
 139                 foreach ($records as $record) {
 140                     if (empty($teachers[$record->id])) {
 141                         $users[$record->id] = 1;
 142                     }
 143                 }
 144             }
 145             break;
 146
 147         case 'this': // current user only
 148             $user_ids = $USER->id;
 149             break;
 150
 151         default: // specific user selected by teacher
 152             if (is_numeric($formdata['reportusers'])) {
 153                 $user_ids = $formdata['reportusers'];
 154             }
 155     }
 156     if (empty($user_ids) && count($users)) {
 157         ksort($users);
 158         $user_ids = join(',', array_keys($users));
 159     }
 160     if (empty($user_ids)) {
 161         print_heading(get_string('nousersyet'));
 162         exit;
 163     }
 164
 165     // database table and selection conditions
 166     $table = "{$CFG->prefix}hotpot_attempts a";
 167     $select = "a.hotpot=$hotpot->id AND a.userid IN ($user_ids)";
 168     if ($mode!='overview') {
 169         $select .= ' AND a.status<>'.HOTPOT_STATUS_INPROGRESS;
 170     }
 171
 172     // confine attempts if necessary
 173     switch ($formdata['reportattempts']) {
 174         case 'best':
 175             $function = 'MAX';
 176             $fieldnames = array('score', 'id', 'clickreportid');
 177             $defaultvalue = 0;
 178             break;
 179         case 'first':
 180             $function = 'MIN';
 181             $fieldnames = array('timefinish', 'id', 'clickreportid');
 182             $default_value = time();
 183             break;
 184         case 'last':
 185             $function = 'MAX';
 186             $fieldnames = array('timefinish', 'id', 'clickreportid');
 187             $defaultvalue = time();
 188             break;
 189         default: // 'all' and any others
 190             $function = '';
 191             $fieldnames = array();
 192             $defaultvalue = '';
 193             break;
 194     }
 195     if (empty($function) || empty($fieldnames)) {
 196         // do nothing (i.e. get ALL attempts)
 197     } else {
 198         $groupby = 'userid';
 199         $records = hotpot_get_records_groupby($function, $fieldnames, $table, $select, $groupby);
 200
 201         $select = '';
 202         if ($records) {
 203             $ids = array();
 204             foreach ($records as $record) {
 205                 $ids[] = $record->clickreportid;
 206             }
 207             if (count($ids)) {
 208                 $select = "a.clickreportid IN (".join(',', $ids).")";
 209             }
 210         }
 211     }
 212
 213     // pick out last attempt in each clickreport series
 214     if ($select) {
 215         $cr_attempts = hotpot_get_records_groupby('MAX', array('timefinish', 'id'), $table, $select, 'clickreportid');
 216     } else {
 217         $cr_attempts = array();
 218     }
 219
 220     $fields = 'a.*, u.firstname, u.lastname, u.picture';
 221     if ($mode=='click') {
 222         $fields .= ', u.idnumber';
 223     } else {
 224         // overview, simple and detailed reports
 225         // get last attempt record in clickreport series
 226         $ids = array();
 227         foreach ($cr_attempts as $cr_attempt) {
 228             $ids[] = $cr_attempt->id;
 229         }
 230         if (empty($ids)) {
 231             $select = "";
 232         } else {
 233             $ids = array_unique($ids);
 234             sort($ids);
 235             $select = "a.id IN (".join(',', $ids).")";
 236         }
 237     }
 238
 239     $attempts = array();
 240
 241     if ($select) {
 242         // add user information to SQL query
 243         $select .= ' AND a.userid = u.id';
 244         $table .= ", {$CFG->prefix}user u";
 245         $order = "u.lastname, a.attempt, a.timefinish";
 246         // get the attempts (at last!)
 247         $attempts = get_records_sql("SELECT $fields FROM $table WHERE $select ORDER BY $order");
 248     }
 249
 250     // stop now if no attempts were found
 251     if (empty($attempts)) {
 252         print_heading(get_string('noattemptstoshow','quiz'));
 253         exit;
 254     }
 255
 256     // get the questions
 257     if (!$questions = get_records_select('hotpot_questions', "hotpot='$hotpot->id'")) {
 258         $questions = array();
 259     }
 260
 261     // get grades
 262     $grades = hotpot_get_grades($hotpot, $user_ids);
 263
 264     // get list of attempts by user and set reference to last attempt in clickreport series
 265     $users = array();
 266     foreach ($attempts as $id=>$attempt) {
 267
 268         $userid = $attempt->userid;
 269
 270         if (!isset($users[$userid])) {
 271             $users[$userid]->grade = isset($grades[$userid]) ? $grades[$userid] : '&nbsp;';
 272             $users[$userid]->attempts = array();
 273         }
 274
 275         $users[$userid]->attempts[] = &$attempts[$id];
 276
 277         if ($mode=='click') {
 278             // shortcut to clickreportid (=the id of the FIRST attempt in this clickreport series)
 279             $clickreportid = $attempt->clickreportid;
 280             if (isset($cr_attempts[$clickreportid])) {
 281                 // store id and finish time of LAST attempt in this clickreport series
 282                 $attempts[$id]->cr_lastclick = $cr_attempts[$clickreportid]->id;
 283                 $attempts[$id]->cr_timefinish = $cr_attempts[$clickreportid]->timefinish;
 284             }
 285         }
 286     }
 287
 288     if ($mode!='overview') {
 289
 290         // initialise details of responses to questions in these attempts
 291         foreach ($attempts as $a=>$attempt) {
 292             $attempts[$a]->responses = array();
 293         }
 294         foreach ($questions as $q=>$question) {
 295             $questions[$q]->attempts = array();
 296         }
 297
 298         // get reponses to these attempts
 299         $attempt_ids = join(',',array_keys($attempts));
 300         if (!$responses = get_records_sql("SELECT * FROM {$CFG->prefix}hotpot_responses WHERE attempt IN ($attempt_ids)")) {
 301             $responses = array();
 302         }
 303
 304         // ids of questions used in these responses
 305         $questionids = array();
 306
 307         foreach ($responses as $response) {
 308             // shortcuts to the attempt and question ids
 309             $a = $response->attempt;
 310             $q = $response->question;
 311
 312             // check the attempt and question objects exist
 313             // (if they don't exist, something is very wrong!)
 314             if (isset($attempts[$a]) || isset($questions[$q])) {
 315
 316                 // add the response for this attempt
 317                 $attempts[$a]->responses[$q] = $response;
 318
 319                 // add a reference from the question to the attempt which includes this question
 320                 $questions[$q]->attempts[] = &$attempts[$a];
 321
 322                 // flag this id as being used
 323                 $questionids[$q] = true;
 324             }
 325         }
 326
 327         // remove unused questions
 328         $questionids = array_keys($questionids);
 329         foreach ($questions as $id=>$question) {
 330             if (!in_array($id, $questionids)) {
 331                 unset($questions[$id]);
 332             }
 333         }
 334     }
 335
 336 /// Open the selected hotpot report and display it
 337
 338     if (! is_readable("report/$mode/report.php")) {
 339         error("Report not known (".clean_text($mode).")", $course_homeurl);
 340     }
 341
 342     include("report/default.php");  // Parent class
 343     include("report/$mode/report.php");
 344
 345     $report = new hotpot_report();
 346
 347     if (! $report->display($hotpot, $cm, $course, $users, $attempts, $questions, $formdata)) {
 348         error("Error occurred during report processing!", $course_homeurl);
 349     }
 350
 351     if ($formdata['reportformat']=='htm') {
 352         print_footer($course);
 353     }
 354
 355 //////////////////////////////////////////////
 356 /// functions to delete attempts and responses
 357
 358 function hotpot_grade_heading($hotpot, $formdata) {
 359
 360     global $HOTPOT_GRADEMETHOD;
 361     $grademethod = $HOTPOT_GRADEMETHOD[$hotpot->grademethod];
 362
 363     if ($hotpot->grade!=100) {
 364         $grademethod = "$hotpot->grade x $grademethod/100";
 365     }
 366     if ($formdata['reportformat']=='htm') {
 367         $grademethod = '<font size="1">'.$grademethod.'</font>';
 368     }
 369     $nl = $formdata['reportformat']=='htm' ? '<br />' : "\n";
 370     return get_string('grade')."$nl($grademethod)";
 371 }
 372 function hotpot_delete_selected_attempts(&$hotpot, $del) {
 373
 374     $select = '';
 375     switch ($del) {
 376         case 'all' :
 377             $select = "hotpot='$hotpot->id'";
 378             break;
 379         case 'abandoned':
 380             $select = "hotpot='$hotpot->id' AND status=".HOTPOT_STATUS_ABANDONED;
 381             break;
 382         case 'selection':
 383             $ids = (array)data_submitted();
 384             unset($ids['del']);
 385             unset($ids['id']);
 386             if (!empty($ids)) {
 387                 $select = "hotpot='$hotpot->id' AND clickreportid IN (".implode(',', $ids).")";
 388             }
 389             break;
 390     }
 391
 392     // delete attempts using $select, if it is set
 393     if ($select) {
 394
 395         $table = 'hotpot_attempts';
 396         if ($attempts = get_records_select($table, $select)) {
 397
 398             hotpot_delete_and_notify($table, $select, get_string('attempts', 'quiz'));
 399
 400             $select = 'attempt IN ('.implode(',', array_keys($attempts)).')';
 401             hotpot_delete_and_notify('hotpot_details', $select, get_string('rawdetails', 'hotpot'));
 402             hotpot_delete_and_notify('hotpot_responses', $select, get_string('answer', 'quiz'));
 403
 404             // update grades for all users for this hotpot
 405             hotpot_update_grades($hotpot);
 406         }
 407     }
 408
 409 }
 410
 411 //////////////////////////////////////////////
 412 /// functions to print the report headings and
 413 /// report selector menus
 414
 415 function hotpot_print_report_heading(&$course, &$cm, &$hotpot, &$mode) {
 416     global $CFG;
 417     $strmodulenameplural = get_string("modulenameplural", "hotpot");
 418     $strmodulename  = get_string("modulename", "hotpot");
 419
 420     $title = format_string($course->shortname) . ": $hotpot->name";
 421     $heading = $course->fullname;
 422
 423     $modulecontext = get_context_instance(CONTEXT_MODULE, $cm->id);
 424     if (has_capability('mod/hotpot:viewreport',$modulecontext)) {
 425         if ($mode=='overview' || $mode=='simplestat' || $mode=='fullstat') {
 426             $module = "quiz";
 427         } else {
 428             $module = "hotpot";
 429         }
 430
 431         $navigation = build_navigation(get_string("report$mode", $module), $cm);
 432     } else {
 433         $navigation = build_navigation(get_string("report", "quiz"), $cm);
 434     }
 435
 436     $button = update_module_button($cm->id, $course->id, $strmodulename);
 437     print_header($title, $heading, $navigation, "", "", true, $button, navmenu($course, $cm));
 438     $course_context = get_context_instance(CONTEXT_COURSE, $course->id);
 439     if (has_capability('gradereport/grader:view', $course_context) && has_capability('moodle/grade:viewall', $course_context)) {
 440         echo '<div class="allcoursegrades"><a href="' . $CFG->wwwroot . '/grade/report/grader/index.php?id=' . $course->id . '">'
 441             . get_string('seeallcoursegrades', 'grades') . '</a></div>';
 442     }
 443     print_heading($hotpot->name);
 444 }
 445 function hotpot_print_report_selector(&$course, &$hotpot, &$formdata) {
 446
 447     global $CFG;
 448
 449     $reports = hotpot_get_report_names('overview,simplestat,fullstat');
 450
 451     print '<form method="post" action="'."$CFG->wwwroot/mod/hotpot/report.php?hp=$hotpot->id".'">';
 452     print '<table cellpadding="2" align="center">';
 453
 454     $menus = array();
 455
 456     $menus['mode'] = array();
 457     foreach ($reports as $name) {
 458         if ($name=='overview' || $name=='simplestat' || $name=='fullstat') {
 459             $module = "quiz";   // standard reports
 460         } else if ($name=='click' && empty($hotpot->clickreporting)) {
 461             $module =  "";      // clickreporting is disabled
 462         } else {
 463             $module = "hotpot"; // custom reports
 464         }
 465         if ($module) {
 466             $menus['mode'][$name] = get_string("report$name", $module);
 467         }
 468     }
 469
 470     $menus['reportusers'] = array(
 471         'allusers' => get_string('allusers', 'hotpot'),
 472         'allparticipants' => get_string('allparticipants')
 473     );
 474
 475     // groups
 476     if ($groups = groups_get_all_groups($course->id)) {
 477         foreach ($groups as $gid => $group) {
 478             $menus['reportusers']["group$gid"] = get_string('group').': '.format_string($group->name);
 479         }
 480     }
 481
 482     // get users who have ever atetmpted this HotPot
 483     $users = get_records_sql("
 484         SELECT
 485             u.id, u.firstname, u.lastname
 486         FROM
 487             {$CFG->prefix}user u,
 488             {$CFG->prefix}hotpot_attempts ha
 489         WHERE
 490             u.id = ha.userid AND ha.hotpot=$hotpot->id
 491         ORDER BY
 492             u.lastname
 493     ");
 494
 495     // get context
 496     $cm = get_coursemodule_from_instance('hotpot', $hotpot->id);
 497     $modulecontext = get_context_instance(CONTEXT_MODULE, $cm->id);
 498
 499     // get teachers enrolled students
 500     $teachers = get_users_by_capability($modulecontext, 'mod/hotpot:viewreport', 'u.id,u.firstname,u.lastname', 'u.lastname');
 501     $students = get_users_by_capability($modulecontext, 'mod/hotpot:attempt', 'u.id,u.firstname,u.lastname', 'u.lastname');
 502
 503     // current students
 504     if (!empty($students)) {
 505         $firsttime = true;
 506         foreach ($students as $user) {
 507             if (isset($users[$user->id])) {
 508                 if ($firsttime) {
 509                     $firsttime = false; // so we only do this once
 510                     $menus['reportusers']['existingstudents'] = get_string('existingstudents');
 511                     $menus['reportusers'][] = '------';
 512                 }
 513                 $menus['reportusers']["$user->id"] = fullname($user);
 514                 unset($users[$user->id]);
 515             }
 516         }
 517     }
 518     // others (former students, teachers, admins, course creators)
 519     if (!empty($users)) {
 520         $firsttime = true;
 521         foreach ($users as $user) {
 522             if ($firsttime) {
 523                 $firsttime = false; // so we only do this once
 524                 $menus['reportusers'][] = '======';
 525             }
 526             $menus['reportusers']["$user->id"] = fullname($user);
 527         }
 528     }
 529
 530     $menus['reportattempts'] = array(
 531         'all' => get_string('attemptsall', 'hotpot'),
 532         'best' => get_string('attemptsbest', 'hotpot'),
 533         'first' => get_string('attemptsfirst', 'hotpot'),
 534         'last' => get_string('attemptslast', 'hotpot')
 535     );
 536
 537     print '<tr><td>';
 538     helpbutton('reportcontent', get_string('reportcontent', 'hotpot'), 'hotpot');
 539     print '</td><th align="right" scope="col">'.get_string('reportcontent', 'hotpot').':</th><td colspan="7">';
 540     foreach ($menus as $name => $options) {
 541         $value = $formdata[$name];
 542         print choose_from_menu($options, $name, $value, "", "", 0, true);
 543     };
 544     print '<input type="submit" value="'.get_string('reportbutton', 'hotpot').'" /></td></tr>';
 545
 546     $menus = array();
 547
 548     $menus['reportformat'] = array();
 549     $menus['reportformat']['htm'] = get_string('reportformathtml', 'hotpot');
 550     if (file_exists("$CFG->libdir/excel") || file_exists("$CFG->libdir/excellib.class.php")) {
 551         $menus['reportformat']['xls'] = get_string('reportformatexcel', 'hotpot');
 552     }
 553     $menus['reportformat']['txt'] = get_string('reportformattext', 'hotpot');
 554
 555     if (trim($CFG->hotpot_excelencodings)) {
 556         $menus['reportencoding'] = array(get_string('none')=>'');
 557
 558         $encodings = explode(',', $CFG->hotpot_excelencodings);
 559         foreach ($encodings as $encoding) {
 560
 561             $encoding = trim($encoding);
 562             if ($encoding) {
 563                 $menus['reportencoding'][$encoding] = $encoding;
 564             }
 565         }
 566     }
 567     $menus['reportwrapdata'] = array(
 568         '1' => get_string('yes'),
 569         '0'  => get_string('no'),
 570     );
 571     $menus['reportshowlegend'] = array(
 572         '1' => get_string('yes'),
 573         '0'  => get_string('no'),
 574     );
 575
 576     print '<tr><td>';
 577     helpbutton('reportformat', get_string('reportformat', 'hotpot'), 'hotpot');
 578     print '</td>';
 579     foreach ($menus as $name => $options) {
 580         $value = $formdata[$name];
 581         print '<th align="right" scope="col">'.get_string($name, 'hotpot').':</th><td>'.choose_from_menu($options, $name, $value, "", "", 0, true).'</td>';
 582     }
 583     print '</tr>';
 584
 585     print '</table>';
 586
 587     print '<hr size="1" noshade="noshade" />';
 588     print '</form>'."\n";
 589 }
 590 function hotpot_get_report_names($names='') {
 591     // $names : optional list showing required order reports names
 592
 593     $reports = array();
 594
 595     // convert $names to an array, if necessary (usually is)
 596     if (!is_array($names)) {
 597         $names = explode(',', $names);
 598     }
 599
 600     $plugins = get_list_of_plugins('mod/hotpot/report');
 601     foreach($names as $name) {
 602         if (is_numeric($i = array_search($name, $plugins))) {
 603             $reports[] = $name;
 604             unset($plugins[$i]);
 605         }
 606     }
 607
 608     // append remaining plugins
 609     $reports = array_merge($reports, $plugins);
 610
 611     return $reports;
 612 }
 613 function hotpot_get_report_users($course, $formdata) {
 614     $users = array();
 615
 616     /// Check to see if groups are being used in this module
 617     $groupmode = groupmode($course, $cm); //TODO: there is no $cm defined!
 618     $currentgroup = setup_and_print_groups($course, $groupmode, "report.php?id=$cm->id&mode=simple");
 619
 620     $sort = "u.lastname ASC";
 621
 622     switch ($formdata['reportusers']) {
 623         case 'students':
 624             if ($currentgroup) {
 625                 $users = get_group_students($currentgroup, $sort);
 626             } else {
 627                 $users = get_course_students($course->id, $sort);
 628             }
 629             break;
 630         case 'all':
 631             if ($currentgroup) {
 632                 $users = get_group_users($currentgroup, $sort);
 633             } else {
 634                 $users = get_course_users($course->id, $sort);
 635             }
 636             break;
 637     }
 638
 639     return $users;
 640 }
 641 function hotpot_get_records_groupby($function, $fieldnames, $table, $select, $groupby) {
 642     // $function is an SQL aggregate function (MAX or MIN)
 643
 644     $fields = sql_concat_join("'_'", $fieldnames);
 645     $fields = "$groupby, $function($fields) AS joinedvalues";
 646
 647     if ($fields) {
 648         $records = get_records_sql("SELECT $fields FROM $table WHERE $select GROUP BY $groupby");
 649     }
 650
 651     if (empty($fields) || empty($records)) {
 652         $records = array();
 653     }
 654
 655     $fieldcount = count($fieldnames);
 656
 657     foreach ($records as $id=>$record) {
 658         if (empty($record->joinedvalues)) {
 659             unset($records[$id]);
 660         } else {
 661             $values = explode('_', $record->joinedvalues);
 662
 663             for ($i=0; $i<$fieldcount; $i++) {
 664                 $fieldname = $fieldnames[$i];
 665                 $records[$id]->$fieldname = $values[$i];
 666             }
 667         }
 668         unset($record->joinedvalues);
 669     }
 670
 671     return $records;
 672 }
 673 ?>