PHP DOMDocument：如何使用CUSTOM字段名称解析xml / rss标签？ [英] PHP DOMDocument : How to parse xml/rss Tags with CUSTOM field names?

问题描述

我要解析以下RSS，例如：

I have the below RSS to parse, something like:

<?xml version="1.0" encoding="utf-8"?>
<rss xmlns:x-wr="http://www.w3.org/2002/12/cal/prod/Apple_Comp_628d9d8459c556fa#" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xsd="http://www.w3.org/2001/XMLSchema" xmlns:x-example="http://www.example.com/rss/x-example" xmlns:x-microsoft="http://schemas.microsoft.com/x-microsoft" xmlns:xCal="urn:ietf:params:xml:ns:xcal" version="2.0">
    <channel>
        <item>
            <title>About Apples</title>
            <author>David K. Lowie</title>
            <x-trumba:customfield name="description">This is the description about apples</xCal:customfield>
            <x-trumba:customfield name="category">Fruits,Food,Apple</xCal:customfield>
        </item>
        <item>
            <title>About Oranges</title>
            <author>Marry L. Jones</title>
            <x-trumba:customfield name="description">This is the description about oranges</xCal:customfield>
            <x-trumba:customfield name="category">Fruits,Food,Orange</xCal:customfield>
        </item>
    </channel>
</rss>

在PHP中，我只知道如何读取前两个节点，例如：

In PHP, I only know how to read first two nodes, something like:

$rss = new DOMDocument();
$rss->load( "http://www.example.com/books.rss" );

foreach( $rss->getElementsByTagName("item") as $node ) {
    echo $node->getElementsByTagName("title")->item(0)->nodeValue,
    echo $node->getElementsByTagName("author")->item(0)->nodeValue,
}

但是，这些是问题：

<x-trumba:customfield name="description">This is the description about apples</xCal:customfield>
<x-trumba:customfield name="category">Fruits,Food,Apple</xCal:customfield>

请帮助：

• 如何解析最后一个节点，例如 < x-trumba：customfield name = description> ？

• How to parse the last nodes like <x-trumba:customfield name="description"> ?

（我无法更改RSS源，因为它不受我的控制。）

请帮助。

推荐答案

您的XML无效，前缀 x-trumba为未定义，并且元素的结束标记使用'xCal'前缀，指的是 urn：ietf：params：xml：ns：xcal 。

You XML is invalid, the 'x-trumba' prefix is not defined, and the closing tags of the elements use the 'xCal' prefix, refering to urn:ietf:params:xml:ns:xcal.

因此，用'xCal'替换开头标签的前缀并为'author'固定结尾标签使XML有效。

So replacing the prefix of the opening tags with 'xCal' and fixing the closing tags for 'author' makes the XML valid.

然后可以注册xCalendar命名空间并使用Xpath来获取自定义字段内容：

Then it is possible to register the xCalendar namespace and use Xpath to fetch the custom field contents:

$rss = new DOMDocument();
$rss->load( "http://www.example.com/books.rss" );
$xpath = new DOMXpath($rss);
$xpath->registerNamespace('x', 'urn:ietf:params:xml:ns:xcal');

foreach( $xpath->evaluate("//item") as $item ) {
    echo $xpath->evaluate('string(title)', $item), "\n";
    echo $xpath->evaluate('string(x:customfield[@name="description"])', $item), "\n";
}

输出：

About Apples
This is the description about apples
About Oranges
This is the description about oranges

Xpath表达式使用条件（ [@ name = description] ）过滤 customfield 元素节点。

The Xpath expression use a condition ([@name="description"]) to filter the customfield element nodes.

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