PHP Library For Parsing Xml With a Colons in Tag Names

PHP library for parsing XML with a colons in tag names?

Say you have some xml like this.

<xhtml:div>
  <xhtml:em>italic</xhtml:em>
  <date>2010-02-01 06:00</date>
</xhtml:div>

You can access 'em' like this: $xml->children('xhtml', true)->div->em;

however, if you want the date field, this: $xml->children('xhtml', true)->div->date; wont work, because you are stuck in the xhtml namespace.

you must execute 'children' again to get back to the default namespace:

$xml->children('xhtml', true)->div->children()->date;

PHP Parse XML with colon in tag name using children

First of all, you're using an undefined variable in your foreach loop. You've defined $clipinfo but you're trying to use $clipartinfo in your code.

Second, you're accessing the attributes incorrectly:

<media:thumbnail url="http://openclipart.org/image/foo.png"/>

You're trying to access the URL attribute. This needs to be done with attributes() method.

Change:

$thumb=$clipartinfo->children('media', true)->thumbnail['url'];

to:

$thumb = $clipinfo->children('media', true)->thumbnail->attributes()->url;

Hope this helps!

Simple XML - Dealing With Colons In Nodes

The solution is explained in this nice article. You need the children() method for accessing XML elements which contain a namespace. This code snippet is quoted from the article:

$feed = simplexml_load_file('http://www.sitepoint.com/recent.rdf'); 
foreach ($feed->item as $item) { 
    $ns_dc = $item->children('http://purl.org/dc/elements/1.1/'); 
    echo $ns_dc->date; 
}

Read colon tags values XML PHP

You should use the children() on the $item element to get it's child-elements:

$str =<<< END
<item>
<title> TITLE </title>
<itunes:author> AUTHOR </itunes:author>
<description> TEST </description>
<itunes:subtitle> TEST </itunes:subtitle>
<itunes:summary> TEST </itunes:summary>
<itunes:image href="yoyoyoyo.jpg"/>
<pubDate> YESTERDAY </pubDate>
<itunes:block>no</itunes:block>
<itunes:explicit>no</itunes:explicit>
<itunes:duration>99:99:99</itunes:duration>
<itunes:keywords>key, words</itunes:keywords>
</item>
END;

$result = @simplexml_load_string($str);

$items = $result->xpath("//item");

foreach ($items as $item) {
    echo $item->title . "\n";
    echo $item->pubDate . "\n";
    echo $item->children()->{'itunes:duration'} . "\n";
}

Output:

TITLE
YESTERDAY
99:99:99

Reference - How do I handle Namespaces (Tags and Attributes with a Colon in their Name) in SimpleXML?

What are XML namespaces?

A colon (:) in a tag or attribute name means that the element or attribute is in an XML namespace. Namespaces are a way of combining different XML formats / standards in one document, and keeping track of which names come from which format. The colon, and the part before it, aren't really part of the tag / attribute name, they just indicate which namespace it's in.

An XML namespace has a namespace identifier, which is identified by a URI (a URL or URN). The URI doesn't point at anything, it's just a way for someone to "own" the namespace. For instance, the SOAP standard uses the namespace http://www.w3.org/2003/05/soap-envelope and an OpenDocument file uses (among others) urn:oasis:names:tc:opendocument:xmlns:meta:1.0. The example in the question uses the namespaces http://example.com and https://namespaces.example.org/two.

Within a document, or a section of a document, a namespace is given a local prefix, which is the part you see before the colon. For instance, in different documents, the SOAP namespace might be given the local prefix soap:, SOAP:, SOAP-ENV:, env:, or just ns1:. These names are linked back to the identifier of the namespace using a special xmlns attribute, e.g. xmlns:soap="http://www.w3.org/2003/05/soap-envelope". The choice of prefix in a particular document is completely arbitrary, and could change each time it was generated without changing the meaning.

Finally, there is a default namespace in each document, or section of a document, which is the namespace used for elements with no prefix. It is defined by an xmlns attribute with no :, e.g. xmlns="http://www.w3.org/2003/05/soap-envelope". In the example above, <list> is in the default namespace, which is defined as http://example.com.

Somewhat peculiarly, un-prefixed attributes are never in the default namespace, but in a kind of "void namespace", which the standard doesn't clearly define. See: XML Namespaces and Unprefixed Attributes

SimpleXML gives me an empty object; what's wrong?

If you use print_r, var_dump, or similar "dump structure" functions on a SimpleXML object with namespaces in, some of the contents will not display. It is still there, and can be accessed as described below.

How do you access namespaces in SimpleXML?

SimpleXML provides two main methods for using namespaces:

• The ->children() method allows you to access child elements in a particular namespace. It effectively switches your object to look at that namespace, until you call it again to switch back, or to another namespace.
• The ->attributes() method works in a similar way, but allows you to access attributes in a particular namespace.

For instance, the example above might become:

define('XMLNS_EG1', 'http://example.com');
define('XMLNS_EG2', 'https://namespaces.example.org/two');
define('XMLNS_SEQ', 'urn:example:sequences');

foreach ( $sx->children(XMLNS_EG1)->list->children(XMLNS_EG2)->item as $item ) {
    echo 'Position: ' . $item->attributes(XMLNS_SEQ)->position . "\n";
    echo 'Item: ' . (string)$item . "\n";
}

You can also select the initial namespace when you first parse the XML, using the $namespace_or_prefix parameter, which is the fourth parameter to simplexml_load_string, simplexml_load_file, or new SimpleXMLElement.

For instance, if we created the object this way, we wouldn't need the ->children(XMLNS_EG1) call to access the list element:

$sx = simplexml_load_string($xml, null, 0, XMLNS_EG1);

(Note that if the root element uses a default namespace rather than a prefix, SimpleXML will select it automatically; but since you can't predict which namespace will be the default in future, it's best to always include the $namespace_or_prefix parameter or initial ->children() call.)

Short-hand (not recommended)

As a short-hand, you can also pass the methods the local alias of the namespace, by giving the second parameter as true. Remember that this prefix could change at any time, for instance, a generator might assign prefixes ns1, ns2, etc, and assign them in a different order if the code changes slightly. Relying on the full namespace URIs is always the best approach.

Using this short-hand, the code would become:

foreach ( $sx->list->children('ns2', true)->item as $item ) {
    echo 'Position: ' . $item->attributes('seq', true)->position . "\n";
    echo 'Item: ' . (string)$item . "\n";
}

(This short-hand was added in PHP 5.2, and you may see really old examples using a more long-winded version using $sx->getNamespaces to get a list of prefix-identifier pairs. This is the worst of both worlds, as you're still hard-coding the prefix rather than the identifier.)

XML Parser for colon-separated tags?

The my before the colon is a namespace prefix, and there should be an attribute xmlns:my on either the same element or one of its enclosing elements somewhere higher up which associates a namespace URI with the prefix. All the standard Java XML technologies support namespaces (SAX, DOM and StAX provided with the JRE as well as third party libraries like JDOM and XOM), the thing you need to remember is that you generally refer to elements in any API using the namespace URI and local name (the bit after the colon), not the prefix specifically.

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