/**
  * Returns an array of user profile fields to be included in export
  *
  * @param int $courseid
  * @param bool $includecustomfields
  * @return array An array of stdClass instances with customid, shortname, datatype, default and fullname fields
  */
 public static function get_user_profile_fields($courseid, $includecustomfields = false)
 {
     global $CFG, $DB;
     // Gets the fields that have to be hidden
     $hiddenfields = array_map('trim', explode(',', $CFG->hiddenuserfields));
     $context = context_course::instance($courseid);
     $canseehiddenfields = has_capability('moodle/course:viewhiddenuserfields', $context);
     if ($canseehiddenfields) {
         $hiddenfields = array();
     }
     $fields = array();
     require_once $CFG->dirroot . '/user/lib.php';
     // Loads user_get_default_fields()
     require_once $CFG->dirroot . '/user/profile/lib.php';
     // Loads constants, such as PROFILE_VISIBLE_ALL
     $userdefaultfields = user_get_default_fields();
     // Sets the list of profile fields
     $userprofilefields = array_map('trim', explode(',', $CFG->grade_export_userprofilefields));
     if (!empty($userprofilefields)) {
         foreach ($userprofilefields as $field) {
             $field = trim($field);
             if (in_array($field, $hiddenfields) || !in_array($field, $userdefaultfields)) {
                 continue;
             }
             $obj = new stdClass();
             $obj->customid = 0;
             $obj->shortname = $field;
             $obj->fullname = get_string($field);
             $fields[] = $obj;
         }
     }
     // Sets the list of custom profile fields
     $customprofilefields = array_map('trim', explode(',', $CFG->grade_export_customprofilefields));
     if ($includecustomfields && !empty($customprofilefields)) {
         list($wherefields, $whereparams) = $DB->get_in_or_equal($customprofilefields);
         $customfields = $DB->get_records_sql("SELECT f.*\n                                                    FROM {user_info_field} f\n                                                    JOIN {user_info_category} c ON f.categoryid=c.id\n                                                    WHERE f.shortname {$wherefields}\n                                                    ORDER BY c.sortorder ASC, f.sortorder ASC", $whereparams);
         if (!is_array($customfields)) {
             continue;
         }
         foreach ($customfields as $field) {
             // Make sure we can display this custom field
             if (!in_array($field->shortname, $customprofilefields)) {
                 continue;
             } else {
                 if (in_array($field->shortname, $hiddenfields)) {
                     continue;
                 } else {
                     if ($field->visible != PROFILE_VISIBLE_ALL && !$canseehiddenfields) {
                         continue;
                     }
                 }
             }
             $obj = new stdClass();
             $obj->customid = $field->id;
             $obj->shortname = $field->shortname;
             $obj->fullname = format_string($field->name);
             $obj->datatype = $field->datatype;
             $obj->default = $field->defaultdata;
             $fields[] = $obj;
         }
     }
     return $fields;
 }

    /**
     * Retrieves the list of students to be graded for the assignment.
     *
     * @param int $assignid the assign instance id
     * @param int $groupid the current group id
     * @param string $filter search string to filter the results.
     * @param int $skip Number of records to skip
     * @param int $limit Maximum number of records to return
     * @param bool $onlyids Only return user ids.
     * @param bool $includeenrolments Return courses where the user is enrolled.
     * @return array of warnings and status result
     * @since Moodle 3.1
     * @throws moodle_exception
     */
    public static function list_participants($assignid, $groupid, $filter, $skip, $limit, $onlyids, $includeenrolments) {
        global $DB, $CFG;
        require_once($CFG->dirroot . "/mod/assign/locallib.php");
        require_once($CFG->dirroot . "/user/lib.php");

        $params = self::validate_parameters(self::list_participants_parameters(),
                                            array(
                                                'assignid' => $assignid,
                                                'groupid' => $groupid,
                                                'filter' => $filter,
                                                'skip' => $skip,
                                                'limit' => $limit,
                                                'onlyids' => $onlyids,
                                                'includeenrolments' => $includeenrolments
                                            ));
        $warnings = array();

        list($assign, $course, $cm, $context) = self::validate_assign($params['assignid']);

        require_capability('mod/assign:view', $context);

        $assign->require_view_grades();

        $participants = array();
        if (groups_group_visible($params['groupid'], $course, $cm)) {
            $participants = $assign->list_participants_with_filter_status_and_group($params['groupid']);
        }

        $userfields = user_get_default_fields();
        if (!$params['includeenrolments']) {
            // Remove enrolled courses from users fields to be returned.
            $key = array_search('enrolledcourses', $userfields);
            if ($key !== false) {
                unset($userfields[$key]);
            } else {
                throw new moodle_exception('invaliduserfield', 'error', '', 'enrolledcourses');
            }
        }

        $result = array();
        $index = 0;
        foreach ($participants as $record) {
            // Preserve the fullname set by the assignment.
            $fullname = $record->fullname;
            $searchable = $fullname;
            $match = false;
            if (empty($filter)) {
                $match = true;
            } else {
                $filter = core_text::strtolower($filter);
                $value = core_text::strtolower($searchable);
                if (is_string($value) && (core_text::strpos($value, $filter) !== false)) {
                    $match = true;
                }
            }
            if ($match) {
                $index++;
                if ($index <= $params['skip']) {
                    continue;
                }
                if (($params['limit'] > 0) && (($index - $params['skip']) > $params['limit'])) {
                    break;
                }
                // Now we do the expensive lookup of user details because we completed the filtering.
                if (!$assign->is_blind_marking() && !$params['onlyids']) {
                    $userdetails = user_get_user_details($record, $course, $userfields);
                } else {
                    $userdetails = array('id' => $record->id);
                }
                $userdetails['fullname'] = $fullname;
                $userdetails['submitted'] = $record->submitted;
                $userdetails['requiregrading'] = $record->requiregrading;
                if (!empty($record->groupid)) {
                    $userdetails['groupid'] = $record->groupid;
                }
                if (!empty($record->groupname)) {
                    $userdetails['groupname'] = $record->groupname;
                }

                $result[] = $userdetails;
            }
        }
        return $result;
    }

/**
 *
 * Give user record from mdl_user, build an array conntains
 * all user details
 *
 * Warning: description file urls are 'webservice/pluginfile.php' is use.
 *          it can be changed with $CFG->moodlewstextformatlinkstoimagesfile
 *
 * @param stdClass $user user record from mdl_user
 * @param stdClass $context context object
 * @param stdClass $course moodle course
 * @param array $userfields required fields
 * @return array|null
 */
function user_get_user_details($user, $course = null, array $userfields = array())
{
    global $USER, $DB, $CFG;
    require_once $CFG->dirroot . "/user/profile/lib.php";
    //custom field library
    require_once $CFG->dirroot . "/lib/filelib.php";
    // file handling on description and friends
    $defaultfields = user_get_default_fields();
    if (empty($userfields)) {
        $userfields = $defaultfields;
    }
    foreach ($userfields as $thefield) {
        if (!in_array($thefield, $defaultfields)) {
            throw new moodle_exception('invaliduserfield', 'error', '', $thefield);
        }
    }
    // Make sure id and fullname are included
    if (!in_array('id', $userfields)) {
        $userfields[] = 'id';
    }
    if (!in_array('fullname', $userfields)) {
        $userfields[] = 'fullname';
    }
    if (!empty($course)) {
        $context = context_course::instance($course->id);
        $usercontext = context_user::instance($user->id);
        $canviewdetailscap = has_capability('moodle/user:viewdetails', $context) || has_capability('moodle/user:viewdetails', $usercontext);
    } else {
        $context = context_user::instance($user->id);
        $usercontext = $context;
        $canviewdetailscap = has_capability('moodle/user:viewdetails', $usercontext);
    }
    $currentuser = $user->id == $USER->id;
    $isadmin = is_siteadmin($USER);
    $showuseridentityfields = get_extra_user_fields($context);
    if (!empty($course)) {
        $canviewhiddenuserfields = has_capability('moodle/course:viewhiddenuserfields', $context);
    } else {
        $canviewhiddenuserfields = has_capability('moodle/user:viewhiddendetails', $context);
    }
    $canviewfullnames = has_capability('moodle/site:viewfullnames', $context);
    if (!empty($course)) {
        $canviewuseremail = has_capability('moodle/course:useremail', $context);
    } else {
        $canviewuseremail = false;
    }
    $cannotviewdescription = !empty($CFG->profilesforenrolledusersonly) && !$currentuser && !$DB->record_exists('role_assignments', array('userid' => $user->id));
    if (!empty($course)) {
        $canaccessallgroups = has_capability('moodle/site:accessallgroups', $context);
    } else {
        $canaccessallgroups = false;
    }
    if (!$currentuser && !$canviewdetailscap && !has_coursecontact_role($user->id)) {
        // skip this user details
        return null;
    }
    $userdetails = array();
    $userdetails['id'] = $user->id;
    if (($isadmin or $currentuser) and in_array('username', $userfields)) {
        $userdetails['username'] = $user->username;
    }
    if ($isadmin or $canviewfullnames) {
        if (in_array('firstname', $userfields)) {
            $userdetails['firstname'] = $user->firstname;
        }
        if (in_array('lastname', $userfields)) {
            $userdetails['lastname'] = $user->lastname;
        }
    }
    $userdetails['fullname'] = fullname($user);
    if (in_array('customfields', $userfields)) {
        $fields = $DB->get_recordset_sql("SELECT f.*\n                                            FROM {user_info_field} f\n                                            JOIN {user_info_category} c\n                                                 ON f.categoryid=c.id\n                                        ORDER BY c.sortorder ASC, f.sortorder ASC");
        $userdetails['customfields'] = array();
        foreach ($fields as $field) {
            require_once $CFG->dirroot . '/user/profile/field/' . $field->datatype . '/field.class.php';
            $newfield = 'profile_field_' . $field->datatype;
            $formfield = new $newfield($field->id, $user->id);
            if ($formfield->is_visible() and !$formfield->is_empty()) {
                $userdetails['customfields'][] = array('name' => $formfield->field->name, 'value' => $formfield->data, 'type' => $field->datatype, 'shortname' => $formfield->field->shortname);
            }
        }
        $fields->close();
        // unset customfields if it's empty
        if (empty($userdetails['customfields'])) {
            unset($userdetails['customfields']);
        }
//.........这里部分代码省略.........

/**
 *
 * Give user record from mdl_user, build an array contains all user details.
 *
 * Warning: description file urls are 'webservice/pluginfile.php' is use.
 *          it can be changed with $CFG->moodlewstextformatlinkstoimagesfile
 *
 * @throws moodle_exception
 * @param stdClass $user user record from mdl_user
 * @param stdClass $course moodle course
 * @param array $userfields required fields
 * @return array|null
 */
function user_get_user_details($user, $course = null, array $userfields = array()) {
    global $USER, $DB, $CFG, $PAGE;
    require_once($CFG->dirroot . "/user/profile/lib.php"); // Custom field library.
    require_once($CFG->dirroot . "/lib/filelib.php");      // File handling on description and friends.

    $defaultfields = user_get_default_fields();

    if (empty($userfields)) {
        $userfields = $defaultfields;
    }

    foreach ($userfields as $thefield) {
        if (!in_array($thefield, $defaultfields)) {
            throw new moodle_exception('invaliduserfield', 'error', '', $thefield);
        }
    }

    // Make sure id and fullname are included.
    if (!in_array('id', $userfields)) {
        $userfields[] = 'id';
    }

    if (!in_array('fullname', $userfields)) {
        $userfields[] = 'fullname';
    }

    if (!empty($course)) {
        $context = context_course::instance($course->id);
        $usercontext = context_user::instance($user->id);
        $canviewdetailscap = (has_capability('moodle/user:viewdetails', $context) || has_capability('moodle/user:viewdetails', $usercontext));
    } else {
        $context = context_user::instance($user->id);
        $usercontext = $context;
        $canviewdetailscap = has_capability('moodle/user:viewdetails', $usercontext);
    }

    $currentuser = ($user->id == $USER->id);
    $isadmin = is_siteadmin($USER);

    $showuseridentityfields = get_extra_user_fields($context);

    if (!empty($course)) {
        $canviewhiddenuserfields = has_capability('moodle/course:viewhiddenuserfields', $context);
    } else {
        $canviewhiddenuserfields = has_capability('moodle/user:viewhiddendetails', $context);
    }
    $canviewfullnames = has_capability('moodle/site:viewfullnames', $context);
    if (!empty($course)) {
        $canviewuseremail = has_capability('moodle/course:useremail', $context);
    } else {
        $canviewuseremail = false;
    }
    $cannotviewdescription   = !empty($CFG->profilesforenrolledusersonly) && !$currentuser && !$DB->record_exists('role_assignments', array('userid' => $user->id));
    if (!empty($course)) {
        $canaccessallgroups = has_capability('moodle/site:accessallgroups', $context);
    } else {
        $canaccessallgroups = false;
    }

    if (!$currentuser && !$canviewdetailscap && !has_coursecontact_role($user->id)) {
        // Skip this user details.
        return null;
    }

    $userdetails = array();
    $userdetails['id'] = $user->id;

    if (in_array('username', $userfields)) {
        if ($currentuser or has_capability('moodle/user:viewalldetails', $context)) {
            $userdetails['username'] = $user->username;
        }
    }
    if ($isadmin or $canviewfullnames) {
        if (in_array('firstname', $userfields)) {
            $userdetails['firstname'] = $user->firstname;
        }
        if (in_array('lastname', $userfields)) {
            $userdetails['lastname'] = $user->lastname;
        }
    }
    $userdetails['fullname'] = fullname($user);

    if (in_array('customfields', $userfields)) {
        $fields = $DB->get_recordset_sql("SELECT f.*
                                            FROM {user_info_field} f
                                            JOIN {user_info_category} c
                                                 ON f.categoryid=c.id
//.........这里部分代码省略.........