检查PHP中是否存在xml节点

Question

我有这个simplexml结果对象:

 object(SimpleXMLElement)#207 (2) {
  ["@attributes"]=>
  array(1) {
   ["version"]=>
   string(1) "1"
  }
  ["weather"]=>
  object(SimpleXMLElement)#206 (2) {
   ["@attributes"]=>
   array(1) {
   ["section"]=>
   string(1) "0"
  }
  ["problem_cause"]=>
  object(SimpleXMLElement)#94 (1) {
   ["@attributes"]=>
   array(1) {
   ["data"]=>
   string(0) ""
   }
  }
  }
 }

我需要检查节点"problem_cause"是否存在.即使它是空的,结果也是错误的.在php手册上,我找到了我为我的需求修改的PHP代码:

 function xml_child_exists($xml, $childpath)
 {
    $result = $xml->xpath($childpath);
    if (count($result)) {
        return true;
    } else {
        return false;
    }
 }

 if(xml_child_exists($xml, 'THE_PATH')) //error
 {
  return false;
 }
 return $xml;

我不知道用什么代替xpath查询'THE_PATH'来检查节点是否存在.或者将simplexml对象转换为dom更好吗？

Answer 1

听起来像一个简单的isset()解决了这个问题.

<?php
$s = new SimpleXMLElement('<foo version="1">
  <weather section="0" />
  <problem_cause data="" />
</foo>');
// var_dump($s) produces the same output as in the question, except for the object id numbers.
echo isset($s->problem_cause)  ? '+' : '-';

$s = new SimpleXMLElement('<foo version="1">
  <weather section="0" />
</foo>');
echo isset($s->problem_cause)  ? '+' : '-';

打印时+-没有任何错误/警告消息.