如何使Web服务调用core_comment_get_comments？

Question

我已经有来自注释表的样本注释。我想使用moodle Web服务显示评论数据，但是错误参数总是会出现。

这是评论表中评论的示例 enter image description here 使用的穆迪版本为3.7

<?php

   //===========================================================
   // Web services's Token for connecting to moodle
   $token = 'xxxxxx';
   $domainname = 'http://localhost/moodle';
   $functionname = 'core_comment_get_comments';

   //===========================================================
   $contextlevel1 = new stdClass();
   $contextlevel1 = 'Context_user';
   $contextlevel = array($contextlevel1);

   $instanceid1 = new stdClass();
   $instanceid1 = 2;
   $instanceid = array($instanceid1);

   $component1 = new stdClass();
   $component1 = 'blog';
   $component = array($component1);

   $itemid1 = new stdClass();
   $itemid1 = 1;
   $itemid = array($itemid1);


   $params = array('contextlevel' => $contextlevel,'instanceid'=>$instanceid,'component'=>$component,'itemid'=>$itemid);

   $restformat = 'xml';
   /// REST CALL
   header('Content-Type: text/plain');
   $serverurl = $domainname . '/webservice/rest/server.php'. '?wstoken=' . $token . '&wsfunction='.$functionname;
   require_once('./curl.php');
   $curl = new curl;
   //if rest format == 'xml', then we do not add the param for backward compatibility with Moodle < 2.2
   $restformat = ($restformat == 'json')?'&moodlewsrestformat=' . $restformat:'';
   $resp = $curl->post($serverurl . $restformat, $params);
   print_r($resp);

   //$json_data = json_encode($resp,JSON_PRETTY_PRINT);
   file_put_contents('courses.json', $resp);

     echo '</br>';


   echo '</br>';
   echo "Operation done successfully\n";
?>

我期望的结果是评论表中的“测试博客测试”评论