lib/ajax/ajaxlib.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 /**
  19  * Library functions to facilitate the use of ajax JavaScript in Moodle.
  20  *
  21  * @package   core
  22  * @copyright 2009 Tim Hunt
  23  * @license   http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
  24  */
  25
  26 /**
  27  * You need to call this function if you wish to use the set_user_preference method in javascript_static.php, to white-list the
  28  * preference you want to update from JavaScript, and to specify the type of cleaning you expect to be done on values.
  29  *
  30  * @package  core
  31  * @category preference
  32  * @param    string          $name      the name of the user_perference we should allow to be updated by remote calls.
  33  * @param    integer         $paramtype one of the PARAM_{TYPE} constants, user to clean submitted values before set_user_preference is called.
  34  * @return   null
  35  */
  36 function user_preference_allow_ajax_update($name, $paramtype) {
  37     global $USER, $PAGE;
  38
  39     // Record in the session that this user_preference is allowed to updated remotely.
  40     $USER->ajax_updatable_user_prefs[$name] = $paramtype;
  41 }
  42
  43 /**
  44  * Starts capturing output whilst processing an AJAX request.
  45  *
  46  * This should be used in combination with ajax_check_captured_output to
  47  * report any captured output to the user.
  48  *
  49  * @return Boolean Returns true on success or false on failure.
  50  */
  51 function ajax_capture_output() {
  52     // Start capturing output in case of broken plugins.
  53     return ob_start();
  54 }
  55
  56 /**
  57  * Check captured output for content. If the site has a debug level of
  58  * debugdeveloper set, and the content is non-empty, then throw a coding
  59  * exception which can be captured by the Y.IO request and displayed to the
  60  * user.
  61  *
  62  * @return Any output that was captured.
  63  */
  64 function ajax_check_captured_output() {
  65     global $CFG;
  66
  67     // Retrieve the output - there should be none.
  68     $output = ob_get_contents();
  69     ob_end_clean();
  70
  71     if (!empty($output)) {
  72         $message = 'Unexpected output whilst processing AJAX request. ' .
  73                 'This could be caused by trailing whitespace. Output received: ' .
  74                 var_export($output, true);
  75         if ($CFG->debugdeveloper && !empty($output)) {
  76             // Only throw an error if the site is in debugdeveloper.
  77             throw new coding_exception($message);
  78         }
  79         error_log('Potential coding error: ' . $message);
  80     }
  81     return $output;
  82 }