函数应返回有效的xml.返回';额外内容';错误


Function supposed to return valid xml. Returns 'Extra Content' error instead

我正在建立一个web API,我相信这可以更有效地完成,但这是v0.1。第一步是访问localhost/serverList/api/rest.php?action=allServers&format=xml。这开始下面的链条。我已经删除了代码中不相关的部分,所以这个问题的更短

serverList/api/rest.php

<?php
include 'inc/restFunctions.php';
//several lines of code removed. $functionName = allserversxml
if(in_array($action,$possibleActions)){
    if(in_array($format,$possibleFormats)){
        $functionName = $action.$format;
        $result = $functionName();
        header('Content-type: text/xml');
        $return->flush();
    }
}
?>

服务器列表/api/inc/restFunctions.php

<?php
function getArrayOfFieldNames($queryResults){
    $fieldList = array();
    while($finfo = $queryResults->fetch_field()){
        $fieldName = $finfo->name;
        array_push($fieldList, $fieldName);
    }
    return $fieldList;
}
function getXMLofQuery($queryResults,$xmlTitle){
    $fieldList = getArrayOfFieldNames($queryResults);
    $xml = new XMLWriter();
    $xml->openURI("php://output");
    $xml->startDocument();
    $xml->setIndent(true);
    $title = $xmlTitle;
    $titlePlural = $xmlTitle."s";
    $xml->startElement($titlePlural);
    $fieldIDName = $title."ID";
        while($row = $queryResults->fetch_assoc()){
            $xml->startElement($title);
                $xml->writeAttribute('id', $row[$fieldIDName]);
                foreach($fieldList as $field){
                        $xml->startElement($field);
                            $xml->writeRaw($row[$field]);
                        $xml->endElement();
                    }
            $xml->endElement();
        }
    $xml->endElement();
    return $xml;
}
function allserversxml(){
    global $link; //from config.php file
    $allServerResults = $link->query("SELECT * FROM servers");
    $xml = getXMLofQuery($allServerResults,"server");
    return $xml;
}
?>

问题是,当我转到URL时,我会得到错误error on line 2 at column 1: Extra content at the end of the document. Below is a rendering of the page up to the first error.

然而。。。下面没有渲染。什么东西?

编辑:根据ndm的建议,我能够通过页面的来源获得错误。

Call to a member function flush() on a non-object in C:'path'serverList'api'rest.php on line 29

所以我想我的问题是,当函数返回xml时,在页面上显示xml的最佳方式是什么?

根据错误消息和代码,假设"删除不相关的代码部分"不包括从发布的函数和逻辑流中删除代码,那么您想要调用flush()的变量应该是$result,而不是$return

...
$result = $functionName();
header('Content-type: text/xml');
$result->flush(); // like this