另一个XPath问题。我有一个API要查询，它包含多个嵌套的名称空间。
<feed xmlns:opensearch="http://a9.com/-/spec/opensearch/1.1/" xmlns:media="http://search.yahoo.com/mrss/" xmlns="http://www.w3.org/2005/Atom" xmlns:pamedia="http://paimages.co.uk/pamedia.htm">
<title>
Image / video search results
</title>
<subtitle>
Images / video found containing the search string provided
</subtitle>
<pamedia:found>
2228
</pamedia:found>
<pamedia:perpage>
100
</pamedia:perpage>
<pamedia:page>
1
</pamedia:page>
<opensearch:totalResults>
2228
</opensearch:totalResults>
<opensearch:itemsPerpage>
100
</opensearch:itemsPerpage>
<opensearch:startIndex>
1
</opensearch:startIndex>
<id>
http://images.pressassociation.com/cgi/search_api/?state=search&q=miley
</id>
<link rel="self" href="http://images.pressassociation.com/cgi/search_api/?state=search&q=miley"></link>
<link rel="next" href="http://images.pressassociation.com/cgi/search_api/?state=search&q=miley&offset=2"></link>
<link rel="last" href="http://images.pressassociation.com/cgi/search_api/?state=search&q=miley&offset=23"></link>
<updated>
2013-11-21T09:13:21Z
</updated>
<link rel="self" href="http://images.pressassociation.com/cgi/search_api/?state=search&q=miley">
<updated>
2013-11-21T09:13:21Z
</updated>
<name>
Press Association Images
</name>
<email>
redacted
</email>
</link>
<entry>
<pamedia:media-type>
image/jpeg
</pamedia:media-type>
<pamedia:event_date>
2013-11-14
</pamedia:event_date>
<pamedia:urn>
18209006
</pamedia:urn>
<pamedia:domain>
2
</pamedia:domain>
<pamedia:domain_prefix>
PA
</pamedia:domain_prefix>
<link type="application/vnd.iptc.g2.newsitem+xml" href="http://images.pressassociation.com/meta/2.18209006.xml"></link>
<link rel="related" href="http://images.pressassociation.com/meta/2.18209006.html" type="text/html"></link>
<link rel="related" href="http://images.pressassociation.com/empicsthumbnail/vol183/block3642/18209006.jpg" type="image/jpeg"></link>
<media:thumbnail width="127" medium="image" height="190" url="http://images.pressassociation.com/empicsthumbnail/vol183/block3642/18209006.jpg" type="image/jpeg"></media:thumbnail>
<media:content expression="sample" medium="image" width="511" height="767" url="http://images.pressassociation.com/image/preview/2.18209006.jpg" type="image/jpeg"></media:content>
<media:copyright>
Associated Press
</media:copyright>
<media:content expression="full" medium="photo" width="6041" height="4024" url="http://images.pressassociation.com/image/2.18209006.jpg" type="image/jpeg"></media:content>
<updated>
2013-11-15T10:56:44Z
</updated>
<summary type="html">
Fans wait for singer Miley Cyrus before the Bambi 2013 media awards in Berlin, Germany, Thursday, Nov. 14, 2013. (AP Photo/Gero Breloer)
</summary>
<rights type="html">
UK picture buyers only BRO110
</rights>
<id>
http://images.pressassociation.com/meta/2.18209006.xml
</id>
<title type="html">
2013 Bambi Media Awards - Berlin
</title>
<category term="E"></category>
<author>
<name>
Gero Breloer/AP
</name>
</author>
</entry>
<entry>
<pamedia:media-type>
image/jpeg
</pamedia:media-type>
<pamedia:event_date>
2013-11-14
</pamedia:event_date>
<pamedia:urn>
18207923
</pamedia:urn>
<pamedia:domain>
2
</pamedia:domain>
<pamedia:domain_prefix>
PA
</pamedia:domain_prefix>
<link type="application/vnd.iptc.g2.newsitem+xml" href="http://images.pressassociation.com/meta/2.18207923.xml"></link>
<link rel="related" href="http://images.pressassociation.com/meta/2.18207923.html" type="text/html"></link>
<link rel="related" href="http://images.pressassociation.com/empicsthumbnail/vol183/block3642/18207923.jpg" type="image/jpeg"></link>
<media:thumbnail width="127" medium="image" height="198" url="http://images.pressassociation.com/empicsthumbnail/vol183/block3642/18207923.jpg" type="image/jpeg"></media:thumbnail>
<media:content expression="sample" medium="image" width="511" height="796" url="http://images.pressassociation.com/image/preview/2.18207923.jpg" type="image/jpeg"></media:content>
<media:copyright>
Associated Press
</media:copyright>
<media:content expression="full" medium="photo" width="2801" height="1796" url="http://images.pressassociation.com/image/2.18207923.jpg" type="image/jpeg"></media:content>
<updated>
2013-11-15T10:56:44Z
</updated>
<summary type="html">
Singer Miley Cyrus arrives for the Bambi 2013 media awards in Berlin, Germany, Thursday, Nov. 14, 2013. (AP Photo/Gero Breloer)
</summary>
<rights type="html">
UK picture buyers only BRO105
</rights>
<id>
http://images.pressassociation.com/meta/2.18207923.xml
</id>
<title type="html">
2013 Bambi Media Awards - Berlin
</title>
<category term="E"></category>
<author>
<name>
Gero Breloer/AP
</name>
</author>
</entry>
为了获得media:namespace节点和其他条目节点，我使用以下查询："/namespace:feed/namespace:entry|namespace:entry/media:*'"但是，这样做会将媒体节点作为单独的数组项返回：
rray
(
[0] => SimpleXMLElement Object
(
[link] => Array
(
[0] => SimpleXMLElement Object
(
[@attributes] => Array
(
[href] => http://images.pressassociation.com/meta/2.18209006.xml
[type] => application/vnd.iptc.g2.newsitem+xml
)
)
[1] => SimpleXMLElement Object
(
[@attributes] => Array
(
[href] => http://images.pressassociation.com/meta/2.18209006.html
[rel] => related
[type] => text/html
)
)
[2] => SimpleXMLElement Object
(
[@attributes] => Array
(
[href] => http://images.pressassociation.com/empicsthumbnail/vol183/block3642/18209006.jpg
[rel] => related
[type] => image/jpeg
)
)
)
[updated] => 2013-11-15T10:56:44Z
[summary] => Fans wait for singer Miley Cyrus before the Bambi 2013 media awards in Berlin, Germany, Thursday, Nov. 14, 2013. (AP Photo/Gero Breloer)
[rights] => UK picture buyers only BRO110
[id] => http://images.pressassociation.com/meta/2.18209006.xml
[title] => 2013 Bambi Media Awards - Berlin
[category] => SimpleXMLElement Object
(
[@attributes] => Array
(
[term] => E
)
)
[author] => SimpleXMLElement Object
(
[name] => Gero Breloer/AP
)
)
[1] => SimpleXMLElement Object
(
[@attributes] => Array
(
[url] => http://images.pressassociation.com/empicsthumbnail/vol183/block3642/18209006.jpg
[medium] => image
[type] => image/jpeg
[width] => 127
[height] => 190
)
)
[2] => SimpleXMLElement Object
(
[@attributes] => Array
(
[url] => http://images.pressassociation.com/image/preview/2.18209006.jpg
[medium] => image
[type] => image/jpeg
[expression] => sample
[width] => 511
[height] => 767
)
)
[3] => SimpleXMLElement Object
(
)
[4] => SimpleXMLElement Object
(
[@attributes] => Array
(
[url] => http://images.pressassociation.com/image/2.18209006.jpg
[medium] => photo
[type] => image/jpeg
[expression] => full
[width] => 6041
[height] => 4024
)
)
然而，我要求[1][2][3]&[4] 嵌套在条目节点[0]中以提取值。如果有人能帮助解决这个问题，我将不胜感激。如果可能的话，我希望能够通过一个XPath调用返回所有内容。
要获得入口节点，只需使用表达式的第一部分：
/atom:feed/atom:entry
要获取所有具有媒体子节点的入口节点，可以使用以下表达式：
/atom:feed/atom:entry[.//media:*]
在获得入口节点后，您希望使用另一个表达式，并在query（）/evalate（）的第二个参数中提供上下文。
.//media:*
请注意，您必须在SimpleXml/DOMXpath实例上注册并使用自己的命名空间前缀。
我建议使用DOMXpath:：evaluate（），而不是SimpleXmlElement:：xpath（）。与xpath（）不同，evaluate可以直接返回标量值。像string(.//media:copyright)这样的表达式只适用于evaluate（），而不适用于xpath（）或DOMXpath:：query（）。
下面是一个使用DOM+Xpath查询带有MediaRss:的Atom提要的小示例
$dom = new DOMDocument();
$dom->load('feed.xml');
$xpath = new DOMXpath($dom);
$xpath->registerNamespace('atom', 'http://www.w3.org/2005/Atom');
$xpath->registerNamespace('media', 'http://search.yahoo.com/mrss/');
foreach ($xpath->evaluate('/atom:feed/atom:entry[.//media:thumbnail]', NULL, FALSE) as $entry) {
$href = $xpath->evaluate('string(atom:link[@rel = "related" and @type="text/html"]/@href)', $entry, FALSE);
$src = $xpath->evaluate('string(.//media:thumbnail/@url)', $entry, FALSE);
printf('<a href="%s"><img src="%s"/></a>', $href, $src);
}