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[DomCrawler] Documented xml namespace autodiscovery #2979

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[DomCrawler] Documented xml namespace autodiscovery #2979

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eccd3da
[DomCrawler] Documented xml namespace autodiscovery.
jakzal Sep 13, 2013
174904c
[DomCrawler] Documented changing of default namespace prefix.
jakzal Sep 18, 2013
f7a16c2
[DomCrawler] Documented explicit namespace registration.
jakzal Sep 22, 2013
0924b1a
[DomCrawler] Added a note about removing the default namespace.
jakzal Dec 16, 2013
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58 changes: 58 additions & 0 deletions components/dom_crawler.rst
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Expand Up @@ -95,6 +95,64 @@ To remove a node the anonymous function must return false.
All filter methods return a new :class:`Symfony\\Component\\DomCrawler\\Crawler`
instance with filtered content.

Both :method:`Symfony\\Component\\DomCrawler\\Crawler::filterXPath` and
:method:`Symfony\\Component\\DomCrawler\\Crawler::filter` methods work with
XML namespaces, which can be either automatically discovered or registered
explicitly.

.. versionadded:: 2.4
Auto discovery and explicit registration of namespaces was introduced
in Symfony 2.4.

Consider an XML below:

<?xml version="1.0" encoding="UTF-8"?>
<entry
xmlns="http://www.w3.org/2005/Atom"
xmlns:media="http://search.yahoo.com/mrss/"
xmlns:yt="http://gdata.youtube.com/schemas/2007">
<id>tag:youtube.com,2008:video:kgZRZmEc9j4</id>
<yt:accessControl action="comment" permission="allowed"/>
<yt:accessControl action="videoRespond" permission="moderated"/>
<media:group>
<media:title type="plain">Chordates - CrashCourse Biology #24</media:title>
<yt:aspectRatio>widescreen</yt:aspectRatio>
</media:group>
</entry>

It can be filtered with ``DomCrawler`` without a need to register namespace
aliases both with :method:`Symfony\\Component\\DomCrawler\\Crawler::filterXPath`::

$crawler = $crawler->filterXPath('//default:entry/media:group//yt:aspectRatio');

and :method:`Symfony\\Component\\DomCrawler\\Crawler::filter`::

use Symfony\Component\CssSelector\CssSelector;

CssSelector::disableHtmlExtension();
$crawler = $crawler->filter('default|entry media|group yt|aspectRatio');

.. note::

The default namespace is registered with a prefix "default". It can be
changed with the
:method:`Symfony\\Component\\DomCrawler\\Crawler::setDefaultNamespacePrefix`.

The default namespace is removed when loading the content if it's the only
namespace in the document. It's done to simplify the xpath queries.

Namespaces can be explicitly registered with the
:method:`Symfony\\Component\\DomCrawler\\Crawler::registerNamespace`::

$crawler->registerNamespace('m', 'http://search.yahoo.com/mrss/');
$crawler = $crawler->filterXPath('//m:group//yt:aspectRatio');

.. caution::

To query an XML with a CSS selector, the HTML extension needs to be disabled with
:method:`Symfony\\Component\\CssSelector\\CssSelector::disableHtmlExtension`
to avoid converting the selector to lowercase.

Node Traversing
~~~~~~~~~~~~~~~

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