Predefined Constants

The constants below are defined by this extension, and will only be available when the extension has either been compiled into PHP or dynamically loaded at runtime.

LIBXML_BIGLINES (int): Allows line numbers greater than 65535 to be reported correctly.
Note:
Only available as of PHP 7.0.0 with Libxml >= 2.9.0
LIBXML_COMPACT (int): Activate small nodes allocation optimization. This may speed up your application without needing to change the code.
Note:
Only available in Libxml >= 2.6.21
LIBXML_DTDATTR (int): Default DTD attributes
Caution
Enabling loading of DTD attributes will enable fetching of external entities. The LIBXML_NO_XXE constant can be used to prevent this (only available in Libxml >= 2.13.0, as of PHP 8.4.0).
LIBXML_DTDLOAD (int): Load the external subset
Caution
Enabling loading of external subsets will enable fetching of external entities. The LIBXML_NO_XXE constant can be used to prevent this (only available in Libxml >= 2.13.0, as of PHP 8.4.0).
LIBXML_DTDVALID (int): Validate with the DTD
Caution
Enabling validating the DTD may facilitate XML External Entity (XXE) attacks. The LIBXML_NO_XXE constant can be used to prevent this (only available in Libxml >= 2.13.0, as of PHP 8.4.0).
LIBXML_HTML_NOIMPLIED (int): Sets HTML_PARSE_NOIMPLIED flag, which turns off the automatic adding of implied html/body... elements.
Note:
Only available in Libxml >= 2.7.7 (as of PHP >= 5.4.0)
LIBXML_HTML_NODEFDTD (int): Sets HTML_PARSE_NODEFDTD flag, which prevents a default doctype being added when one is not found.
Note:
Only available in Libxml >= 2.7.8 (as of PHP >= 5.4.0)
LIBXML_LOADED_VERSION (string): Version of libxml's core parser module.
LIBXML_NOBLANKS (int): Remove blank nodes
LIBXML_NOCDATA (int): Merge CDATA as text nodes
LIBXML_NOEMPTYTAG (int): Expand empty tags (e.g. <br/> to <br></br>)
Note:
This option is currently just available in the DOMDocument::save and DOMDocument::saveXML functions.
LIBXML_NOENT (int): Substitute entities
Caution
Enabling entity substitution may facilitate XML External Entity (XXE) attacks.
LIBXML_NOERROR (int): Suppress error reports
LIBXML_NONET (int): Disable network access when loading documents
LIBXML_NOWARNING (int): Suppress warning reports
LIBXML_NOXMLDECL (int): Drop the XML declaration when saving a document
Note:
Only available in Libxml >= 2.6.21
LIBXML_NO_XXE (int): Disables XML External Entities (XXE) when performing entity substitution
Note:
Only available in Libxml >= 2.13.0, as of PHP 8.4.0
LIBXML_NSCLEAN (int): Remove redundant namespace declarations
LIBXML_PARSEHUGE (int): Sets XML_PARSE_HUGE flag, which relaxes any hardcoded limit from the parser. This affects limits like maximum depth of a document or the entity recursion, as well as limits of the size of text nodes.
Note:
Only available in Libxml >= 2.7.0 (as of PHP >= 5.3.2 and PHP >= 5.2.12)
LIBXML_PEDANTIC (int): Sets XML_PARSE_PEDANTIC flag, which enables pedantic error reporting.
Note:
Available as of PHP >= 5.4.0
LIBXML_RECOVER (int): Enables recovery mode when parsing a document.
Note:
Only available as of PHP 8.4.0
LIBXML_XINCLUDE (int): Implement XInclude substitution
LIBXML_ERR_ERROR (int): A recoverable error
LIBXML_ERR_FATAL (int): A fatal error
LIBXML_ERR_NONE (int): No errors
LIBXML_ERR_WARNING (int): A simple warning
LIBXML_VERSION (int): libxml version like 20605 or 20617
LIBXML_DOTTED_VERSION (string): libxml version like 2.6.5 or 2.6.17
LIBXML_SCHEMA_CREATE (int): Create default/fixed value nodes during XSD schema validation
Note:
Only available in Libxml >= 2.6.14 (as of PHP >= 5.5.2)

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User Contributed Notes 5 notes

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@oneseventeen ¶

13 years ago

When inserting XML DOM Elements inside existing XML DOM Elements that I loaded from an XML file using the following code, none of my new elements were formatted correctly, they just showed up on one line:

<?php 
$dom = DOMDocument::load('file.xml'); 
$dom->formatOutput = true;
//$dom->add some new elements with child nodes somewhere inside the loaded XML using insertBefore();
$dom->saveXML();
//output: everything looks normal but the new nodes are all on one line.
?>

I found I could pass LIBXML_NOBLANKS to the load method and it would reformat the whole document, including my added stuff:
<?php 
$dom = DOMDocument::load('file.xml', LIBXML_NOBLANKS); 
$dom->formatOutput = true;
//$dom->add some new elements with child nodes somewhere inside the loaded XML using insertBefore();
$dom->saveXML();
//output: everything looks newly formatted, including new nodes
?>

Hope this helps, took me hours of trial and error to figure this out!

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siraic at gmail dot com ¶

3 years ago

The name of the constant LIBXML_NOENT is very misleading. Adding this flag actually causes the parser to load and insert the external entities. Omitting it leaves the tags untouched, which is probably what you want.

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vetalstar at mail dot ru ¶

6 years ago

LIBXML_DOTTED_VERSION option doesn't work.
libxml version: 2.9.4

<?php

echo LIBXML_DOTTED_VERSION;
$xml = new SimpleXMLElement('<fasa_request id="1234567"/>', LIBXML_NOXMLDECL);

?>

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Ismael Miguel ¶

1 year ago

If you want to save without the XML declaration, and LIBXML_NOXMLDECL doesn't work for you, you can just do this:

<?php
$doc = new \DOMDocument('1.0', 'UTF-8');
$doc->loadXML($xml, LIBXML_*);

echo $doc->saveXML($doc->firstElementChild);
?>

This will output the XML without the XML declaration and without using the flag.
You also don't need to do fiddly replacements and pray that it works.

down

zachatwork at gmail dot com ¶

14 years ago

Note: The LIBXML_NOXMLDECL constant is defined in this library but is not supported by DOMDocument (yet).

See also: http://bugs.php.net/bug.php?id=47137

<?php

print "PHP_VERSION:      ".PHP_VERSION."\n";
print "LIBXML_VERSION:   ".LIBXML_VERSION."\n";
print "LIBXML_NOXMLDECL: ".LIBXML_NOXMLDECL."\n";

$dom = new DomDocument();
$dom->loadXML("<foo />");

# This should work but doesn't.

print "DOMDocument doesn't honor LIBXML_NOXMLDECL:\n";
print $dom->saveXML(null,LIBXML_NOXMLDECL);

# This works, and will still work after the above is fixed.

print "Forwards compatible workaround:\n";
$lines = explode("\n", $dom->saveXML(null, LIBXML_NOXMLDECL), 2);
if(!preg_match('/^\<\?xml/', $lines[0]))
    print $lines[0];
print $lines[1];

?>

PHP_VERSION:      5.3.1-0.dotdeb.1
LIBXML_VERSION:   20632
LIBXML_NOXMLDECL: 2
DOMDocument doesn't honor LIBXML_NOXMLDECL:
<?xml version="1.0"?>
<foo/>
Forwards compatible workaround:
<foo/>

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