使用PHP DOMDocument从带有冒号的命名空间的xml节点获取值

Question

I'm parsing xml document using DOMDocument class. First I've selected all nodes with name 'item' using $xml->getElementsByTagName('item') method. My sample xml file looks like this:

<item>
      <title>...</link>
      <description>...</description>
      <pubDate>...</pubDate>
      <ns:author>...</dc:creator>
</item>

However my problem is getting value from nested tag with namespace name with colon sign. I get values from nodes without namespaces in foreach using $node->getElementsByTagName('description')->item(0)->nodeValue and there is no errors.

I also found method getElementsByTagNameNs() to get nodes with it's namespaces. However when i try to get nodeValue like previous nodes without namespace I get "PHP Notice: Trying to get property of non-object". I think it is strange because getElementsByTagNameNs()->item(0) returns object DOMElement.

Do you know how to take value from node with namespace, in this case <ns:author></dc:creator> element?

Answer 1

As the document fragment you give isn't complete and even valid, I've had to make a few changes. You say you want the value of <ns:author>...</dc:creator> which is not a valid element as the open and close names are different in both name and namespace, you would expect something like <ns:author>...</ns:author>

As an example of how you can fetch the values from a namespace (using some corrected and some guessed alterations to the XML)...

$xml = <<<XML
<?xml version="1.0"?>
<items xmlns:ns="http://some.url">
    <item>
      <title>title</title>
      <description>Descr.</description>
      <pubDate>1/1/1970</pubDate>
      <ns:author>author1</ns:author>
    </item>
</items>
XML;

$dom = new DOMDocument( '1.0', 'utf-8' );
$dom->loadXML($xml);
$items = $dom->getElementsByTagName('item');
foreach ( $items as $item )  {
    $author = $item->getElementsByTagNameNS("http://some.url", "*")->item(0)->nodeValue;
    echo "Author = ".$author.PHP_EOL;
}

In getElementsByTagNameNS() you will need to put in the correct URL for this namespace, which should be in the source document.

This outputs...

Author = author1