DOMDocument::load()

(PHP 5, PHP 7)

Load XML from a file

说明

publicDOMDocument::load(string $filename[,int $options= 0]): mixed

Loads an XML document from a file.

Warning
Unix style paths with forward slashes can cause significant performance degradation on Windows systems; be sure to call realpath() in such a case.

参数

$filename: The path to the XML document.
$options: BitwiseORof the libxml option constants.

返回值

成功时返回TRUE，或者在失败时返回FALSE。 If called statically, returns a DOMDocument或者在失败时返回FALSE.

错误／异常

If an empty string is passed as the$filenameor an empty file is named, a warning will be generated. This warning is not generated by libxml and cannot be handled using libxml's error handling functions.

此方法可以被静态调用,但会抛出一个E_STRICT错误。

范例

Example #1 Creating a Document

<?php
$doc = new DOMDocument();
$doc->load('book.xml');
echo $doc->saveXML();
?>

参见

DOMDocument::loadXML() Load XML from a string
DOMDocument::save() Dumps the internal XML tree back into a file
DOMDocument::saveXML() Dumps the internal XML tree back into a string

I had a problem with loading documents over HTTP. I would get errors looking like this:
Warning: DOMDocument::load(http://external/document.xml): failed to open stream: HTTP request failed! HTTP/1.1 500 Internal Server Error
The document would load fine in browsers and using wget. The problem is that DOMDocument::load() on my systems (both OS X and Linux) didn't send any User-Agent header which for some weird reason made Microsoft-IIS/6.0 respond with the 500 error.
The solution is found on http://php.net/manual/en/function.libxml-set-streams-context.php : 
<?php
$opts = array(
  'http' => array(
    'user_agent' => 'PHP libxml agent',
  )
);
$context = stream_context_create($opts);
libxml_set_streams_context($context);
// request a file through HTTP
$doc = DOMDocument::load('http://www.example.com/file.xml');
?>

in the default example:
<?php
$doc = new DOMDocument();
$doc->load('book.xml');
echo $doc->saveXML();
?>
you must enter the absolute path for book.xml due for get a false result in load function.

NOTE, will not load successfully if there is a comment at the beginning of the file before the <?xml version="1.0" ?> declaration!

Note that this method uses the local file system before doing anything remote. The 'disadvantage' would be that if you would do the following:
<?php
$xml = new DOMDocument;
$xml->load("xmlsource/news.php");
?>
This would not make the method read the actual output of the news.php file --presumably valid xml data--, but the file contents --obviously this would be php code. So this will return an error saying news.php is missing the xml declaration and maybe the xml start-tag
What would work is the following:
<?php
$xml = new DOMDocument;
$xml->load("http://my.beautiful-website.com/xmlsource/news.php");
?>
This will force a http request to be used to get this file instead of just locally reading it and the file just returning code

BadGuy´s note may be confusing since what he depicts is no special property of the relevant method. PHP works always in and on a local file system which means that if you want to use resources from other systems or - what is, indeed, BadGuy´s problem - need resources that have been dealt with by other programs or processes, you have to state and manage that explicitly in your code. PHP is just a quite normal program in that.
BadGuy´s solution is using the "http wrapper" to get output from another process (see "wrappers" in the PHP manual). Doing this, the appropriate syntax for http calls has to be respected.

i've found the partial solution for xml:id warning,is explained at this address: https://fosswiki.liip.ch/display/BLOG/GetElementById+Pitfalls
there explains that:
The ID does have to be a valid NCName, which for example means, that the first letter can't be a number.
and in my xml:id i had a number. :D

XHTML and entities: The solution proposed below by zachatwork at gmail dot com didn't work for me. I checked on a number of servers (both LAMPP and WAMPP) - on each of them, calling loadXML() with the LIBXML_DTDLOAD option triggered an external request for the DTD. And that's bad news.
If allow_url_fopen is turned off, the request for the DTD fails with a warning. If it is turned on, the request fails because these w3c URLs return a 503 Service Unavailable.
HTML entities still generate a warning in either case. 
The best solution, as far as I can tell, is simply to ignore the warnings and suppress them using '@'. I can't recommend parsing XHTML with loadHTML() instead of loadXML() - yes, you get rid of the entity problem, but loadHTML() changes the source while parsing it (tries to 'fix' it even though there is nothing to fix).

Function will not work if using XML DOM PECL module

If you are loading xml with the intention of validating it against an internal dtd and you have experienced issues with the validation it could be related to missing LIBXML constants.
I found this post by "aidan at php dot net" in root level dom docs and thought it might be more useful here:
As of PHP 5.1, libxml options may be set using constants rather than the use of proprietary DomDocument properties.
DomDocument->resolveExternals is equivilant to setting
LIBXML_DTDLOAD
LIBXML_DTDATTR
DomDocument->validateOnParse is equivilant to setting
LIBXML_DTDLOAD
LIBXML_DTDVALID
PHP 5.1 users are encouraged to use the new constants.
Example:
<?php
$dom = new DOMDocument;
// Resolve externals
$dom->load($file, LIBXML_DTDLOAD|LIBXML_DTDATTR);
// OR 
// Validate against DTD
$dom->load($file, LIBXML_DTDLOAD|LIBXML_DTDVALID);
$dom->validate();
?>

In reply to BadGuy [at] BadGuy [dot] nl
When the news.php file is located on the same server, like you said in the first example then http://my.beautiful-website.com/xmlsource/news.php wouldn't work, but you should use http://localhost/xmlsource/news.php or http://127.0.0.1/xmlsource/news.php

You can easily avoid the warning about &nbsp; references by using the LIBXML_DTDLOAD option. 
<?php
$html = <<<EOF
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
 <head>
 </head>
 <body>
  <p>&nbsp;</p>
 </body>
</html>
EOF;
// This one works perfectly.
$dom = new DOMDocument();
$dom->loadXML($html, LIBXML_DTDLOAD);
print $dom->saveXML();
// This one produces a warning.
$dom = new DOMDocument();
$dom->loadXML($html);
print $dom->saveXML();
?>
See also: http://www.php.net/manual/en/libxml.constants.php
Note that libxml will detect that your DTD is locally available via /etc/xml/catalog. So there is no worry about this causing your DOM loads to make external network requests.

Suppose you wanted to dynamically load an array from an .XSD file. This method is your guy. just remember to use the actual xs: portion in xpaths and such.
All the other "load" methods will error out.
<?php
$attributes = array();
$xsdstring = "/htdocs/api/xsd/common.xsd";
$XSDDOC = new DOMDocument();
$XSDDOC->preserveWhiteSpace = false;
if ($XSDDOC->load($xsdstring))
{
  $xsdpath = new DOMXPath($XSDDOC);
  $attributeNodes = 
       $xsdpath->
       query('//xs:simpleType[@name="attributeType"]')
       ->item(0);
  foreach ($attributeNodes->childNodes as $attr) 
  {
    $attributes[ $attr->getAttribute('value') ] = $attr->getAttribute('name');
  }
  unset($xsdpath);
}
print_r($attributes);
?>

load() will handle non-ASCII characters depending on the details of the XML declaration, but in a somewhat surprising way. One would assume that the declarations '<?xml version="1.0" encoding="UTF-8"?>' and '<?xml version="1.0"?>' are treated in the same way because UTF-8 is the default encoding anyway. But not so.
* If there is an XML declaration defining the encoding *explicitly*, the non-ASCII characters remain unchanged.
* If the XML declaration does not define the encoding explicitly, or if the XML declaration is missing, non-ASCII characters are converted into numeric entities.
So the document
  <?xml version="1.0"?>
  <root><nonascii>ä</nonascii></root>
will be converted to
  <?xml version="1.0"?>
  <root><nonascii>&#xE4;</nonascii></root>
The same happens if there is no XML declaration at all. On the other hand, the document
  <?xml version="1.0" encoding="UTF-8"?>
  <root><nonascii>ä</nonascii></root>
will remain as it is.
This behaviour applies to loadXML() as well.

adding an id for a child, when i use abstract mode i get the following warning:
[quote]Warning: DOMDocument::load() [domdocument.load]: xml:id : attribute value xx is not an NCName in /fake/path/to/xmlfile[/quote]