检查PHP中是否存在xml节点

问题描述

我有这个simplexml结果对象:

I have this simplexml result object:

 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.即使它为空，结果也是一个错误.在php手册上，我找到了为自己的需要修改的以下php代码:

I need to check if the node "problem_cause" exists. Even if it is empty, the result is an error.On the php manual, I found this php code that I modified for my needs:

 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;

我不知道该用什么代替xpath查询"THE_PATH"来检查该节点是否存在.还是将simplexml对象转换为dom更好?

I have no idea what to put in place of the xpath query 'THE_PATH' to check if the node exists.Or is it better to convert the simplexml object to dom?

推荐答案

听起来像一个简单的 isset()解决了这个问题.

Sounds like a simple isset() solves this problem.

<?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+-，没有任何错误/警告消息.

prints +- without any error/warning message.

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