Php 通过XMLDOM工作？

我是XMLDOM新手，我正在尝试检索标记中的值。 问题是我不知道如何在dom中工作到那个级别。 我尝试过这样做：

itemXML.getElementById("gender").getElementsByTagName("item").nodeValue;

但是如果返回“undefined”，我将如何指定要检索其值的标记

以下是我的xml文档的内容：

  <dataFields>
    <items id="gender">
          <item>Male</item>
      <item>Female</item>
    </items>
<items id="age">
    <item>0-3 years</item>
    <item>3-6 years</item>
    <item>7-16 years</item> 
    <item>17-25 years</item>
    <item>26-40 years</item>
    <item>41-65 years</item> 
    <item>65+ years</item>
</items>

没有名称空间前缀的XML中的id属性只是普通属性，只有在html中它才是标识符。因此，在xml文档中，属性名必须是xml:id才能由getElementById找到。getElementsByTagName方法返回元素节点列表，而不仅仅是一个。您必须使用foreach或item方法来访问列表中的元素

但这里有一个更简单的方法。DOMXpath:evaluate允许您使用xpath表达式从DOM获取节点和值

以下是一些演示源：

$xml = <<<'XML'
<dataFields>
  <items id="gender" xml:id="xml_gender">
    <item>Male</item>
    <item>Female</item>
  </items> 
  <items id="age">
    <item>0-3 years</item>
    <item>3-6 years</item>
    <item>7-16 years</item> 
    <item>17-25 years</item>
    <item>26-40 years</item>
    <item>41-65 years</item> 
    <item>65+ years</item>
  </items>
</dataFields>
XML;

$dom = new DOMDocument();
$dom->loadXml($xml);

// difference between id and xml:id
var_dump(
  $dom->getElementById('gender'),
  get_class($dom->getElementById('xml_gender'))
);
/* Output:
NULL
string(10) "DOMElement"
*/

// getElementsByTagName returns a node list
var_dump(
  get_class($dom->getElementById('xml_gender')->getElementsByTagName('item'))
);
/* Output:
NULL
string(11) "DOMNodeList"
*/

// you can iterate node lists
foreach ($dom->getElementById('xml_gender')->getElementsByTagName('item') as $item) {
  var_dump($item->nodeValue);
}
/* Output:
string(4) "Male"
string(6) "Female"
*/

// it is easier with xpath
$xpath = new DOMXpath($dom);
foreach ($xpath->evaluate('//items[@id = "gender"]/item') as $item) {
  var_dump($item->nodeValue);
}
/* Output:
string(4) "Male"
string(6) "Female"
*/

// DOMXpath::evaluate() can be used to fetch values directly, too.
var_dump(
  $xpath->evaluate('string(//items[@id = "gender"]/item[2])')
);
/* Output:
string(6) "Female"
*/

---

嗯，这比我想做的要好一百万倍。我刚刚实现了它，它完全满足了我的需要，但比我将要使用的代码少了100行。非常感谢！

$xpath = new DOMXPath($itemXML);

$genderItems = $xpath->query('/dataFields/items[@id="gender"]/item');

foreach ($genderItems as $genderItem) {

    echo $genderItem->nodeValue . "\n"; // "Male", "Female"

}

$xml = <<<'XML'
<dataFields>
  <items id="gender" xml:id="xml_gender">
    <item>Male</item>
    <item>Female</item>
  </items> 
  <items id="age">
    <item>0-3 years</item>
    <item>3-6 years</item>
    <item>7-16 years</item> 
    <item>17-25 years</item>
    <item>26-40 years</item>
    <item>41-65 years</item> 
    <item>65+ years</item>
  </items>
</dataFields>
XML;

$dom = new DOMDocument();
$dom->loadXml($xml);

// difference between id and xml:id
var_dump(
  $dom->getElementById('gender'),
  get_class($dom->getElementById('xml_gender'))
);
/* Output:
NULL
string(10) "DOMElement"
*/

// getElementsByTagName returns a node list
var_dump(
  get_class($dom->getElementById('xml_gender')->getElementsByTagName('item'))
);
/* Output:
NULL
string(11) "DOMNodeList"
*/

// you can iterate node lists
foreach ($dom->getElementById('xml_gender')->getElementsByTagName('item') as $item) {
  var_dump($item->nodeValue);
}
/* Output:
string(4) "Male"
string(6) "Female"
*/

// it is easier with xpath
$xpath = new DOMXpath($dom);
foreach ($xpath->evaluate('//items[@id = "gender"]/item') as $item) {
  var_dump($item->nodeValue);
}
/* Output:
string(4) "Male"
string(6) "Female"
*/

// DOMXpath::evaluate() can be used to fetch values directly, too.
var_dump(
  $xpath->evaluate('string(//items[@id = "gender"]/item[2])')
);
/* Output:
string(6) "Female"
*/