DOMDocument::saveXML

(PHP 5, PHP 7, PHP 8)

DOMDocument::saveXML — Dumps the internal XML tree back into a string

说明

public DOMDocument::saveXML(?DOMNode $node = null, int $options = 0): string|false

Creates an XML document from the DOM representation. This function is usually called after building a new dom document from scratch as in the example below.

参数

node: Use this parameter to output only a specific node without XML declaration rather than the entire document.
options: Additional Options. The LIBXML_NOEMPTYTAG and LIBXML_NOXMLDECL options are supported. Prior to PHP 8.3.0, only the LIBXML_NOEMPTYTAG option is supported.

返回值

Returns the XML, or false if an error occurred.

错误／异常

DOM_WRONG_DOCUMENT_ERR: Raised if node is from another document.

更新日志

版本	说明
8.3.0	LIBXML_NOXMLDECL is now supported.

示例

示例 #1 Saving a DOM tree into a string

<?php

$doc = new DOMDocument('1.0');
// we want a nice output
$doc->formatOutput = true;

$root = $doc->createElement('book');
$root = $doc->appendChild($root);

$title = $doc->createElement('title');
$title = $root->appendChild($title);

$text = $doc->createTextNode('This is the title');
$text = $title->appendChild($text);

echo "Saving all the document:\n";
echo $doc->saveXML() . "\n";

echo "Saving only the title part:\n";
echo $doc->saveXML($title);

?>

以上示例会输出：

Saving all the document:
<?xml version="1.0"?>
<book>
  <title>This is the title</title>
</book>

Saving only the title part:
<title>This is the title</title>

参见

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

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＋添加备注

用户贡献的备注 16 notes

down

liumenglei0211 at 163 dot com ¶

5 years ago

How to display two tags when the node content is empty.

<?php
$dom     = new \DOMDocument('1.0');
$document = $dom->createElement('document');
$document = $dom->appendChild($document);
$head = $dom->createElement('title','this is title');
$content = $dom->createElement('content','');
$document->appendChild($head);
$document->appendChild($content);
echo $dom->saveXML();
?>

In XML, they are considered exactly the same thing, and any parser should recognize both forms.However, you can write it this way if you still need it

<?php
echo $dom->saveXML($dom->documentElement, LIBXML_NOEMPTYTAG);
?>

Example 1：

<?xml version="1.0"?>
<document>
    <title>this is title</title>
    <content/>
</document>

Example 2：
<document>
    <title>this is test</title>
    <content></content>
</document>

down

devin at SPAMISBAD dot tritarget dot com ¶

18 years ago

It took some searching to figure this one out. I didn't see much in the way of explaining this glitch in the manual thus far. (For PHP5 I believe)

formatOutput = true; appears to fail when the origin of the DOM came from a file via load(). EX:

<?php
    $dom = new DOMDocument();
    $dom->load ("test.xml");
    $dom->formatOutput = true;

    $new_tag = $dom->createElement ('testNode');
    $new_tag->appendChild (
        $dom->createElement ('test', 'this is a test'));
    $dom->documentElement->appendChild ($new_tag);

    printf ("<pre>%s</pre>", htmlentities ($dom->saveXML()));
?>

Will not indent the output and will display the modified nodes all in one long line. Makes for editing a config.xml a bit difficult when saving to a file.

By adding the preserveWhiteSpace = false; BEFORE the load() the formatOutput works as expected. EX:

<?php
    $dom = new DOMDocument();
    $dom->preserveWhiteSpace = false;
    $dom->load ("test.xml");
    $dom->formatOutput = true;

    $new_tag = $dom->createElement ('testNode');
    $new_tag->appendChild (
        $dom->createElement ('test', 'this is a test'));
    $dom->documentElement->appendChild ($new_tag);

    printf ("<pre>%s</pre>", htmlentities ($dom->saveXML()));
?>

CAUTION: If your loaded xml file (test.xml) has an empty root node that is not shortened or has no children this will NOT work.

Example:

DOES NOT WORK:
<?xml version="1.0"?>
<root>
</root>

WORKS:
<?xml version="1.0"?>
<root/>

WORKS:
<?xml version="1.0"?>
<root>
  <!-- comment -->
</root>

WORKS:
<?xml version="1.0"?>
<root>
  <child/>
</root>

down

vikramvmalhotra at hotmail dot com ¶

15 years ago

if you are storing multi-byte characters in XML, then saving the XML using saveXML() will create problems. It will spit out the characters converted in encoded format.



<?php

$str = domdoc->saveXML(); // gives "&x#1245;" some encoded data

?>



Instead do the following



<?php

$str = domdoc->saveXML(domdoc->documentElement); // gives "保存しました" correct multi-byte data

?>

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padys at tlen dot pl ¶

20 years ago

When you save whole document:
DOMDocument->saveXML() produces string in encoding defined in property DOMDocument->encoding.

When you save only one node:
DOMDocument->saveXML(DOMNode) produces always string in UTF-8.

down

mswiercz at mwerk dot com ¶

20 years ago

Quick tip to minimize memory when generating documents with DOM.

Rather than using
   $xmlStr = DOMDocument->saveXML();
   echo $xmlStr;

to dump a large DOM to the output buffer, use a PHP output stream, as in

   DOMDocument->save('php://output');

A lot of memory will be saved when generating large DOMs.

down

qjerry.com at gmail.com ¶

15 years ago

The simpliest (and probably the fastest) way to strip an XML declaration (<?xml version="1.0" ... ?>) out of output document, is to output child nodes of DOMDocument separately:

<?php

$document = new DOMDocument();
$document->load('/some/file.xml');

// this will also output doctype and comments at top level
foreach($document->childNodes as $node)
    $result .= $document->saveXML($node)."\n";

echo $result;

?>

This might be userful when dealing with browser compatibility issues, for example, well known problem with valid XHTML in IE6.

down

JITR ¶

17 years ago

Comment to `devin at SPAMISBAD dot tritarget dot com''s post:

Thanks for pointing out the pitfalls of `formatOutput' vs. `load*()'. This has certainly saved me from some possible surprises.

I think the seemingly strange behaviour can be explained. Warning: The following stuff is mostly based on deductions and experiments. Much less on studying the sources and specs (I'm not sure some of these would provide answer anyway, at least not easily).

As you point out, `preserveWhiteSpace' must be set before loading the DOM from the source string (I'm working with `loadXML()' but I believe the situation should be the same with `load()' you used). This looks logical, as this property seems to control the parsing and DOM creation process during which text nodes containing the whitespace are either included or dropped. This can be proven by dumping the DOM structure and comparing the results based on the value of `preserveWhiteSpace'. With `preserveWhiteSpace' set to `FALSE', no text nodes containing whitespace will be present in the returned DOM. When this property is `TRUE', these nodes will be present.

Note: When speaking about the whitespace in the previous paragraph, we're most certainly speaking about so called `whitespace in element content' or `element content whitespace', if I'm not mistaken. See also my comment in the notes of `DOMText->isWhitespaceInElementContent()' method.

As for the mysterious effect on the output of `saveXLM()', I think the explanation lies in the presence or absence of the above mentioned whitespace text nodes. This was also proven by experiments: After adding such a node into a DOM which contained none (the DOM was created using `loadXML()' with `preserveWhiteSpace' set to `FALSE'), the output formatting got affected in a such a way, the formatting got lost for the rest of the document after the added node. I think the presence of whitespace text nodes forces such rendering, that the content of these nodes is used to separate adjoining nodes thus disabling default formatting. Only when there are no such text nodes present, the ouput formatting takes effect (provided the `formatOutput' is set to `TRUE', of course).

Well, the thing I don't really understand is how you did get an output of a signle line with `formatOutput' set to `TRUE'. This has happened to me when no whitespace text nodes were present (ie. when loading the XML with `preserveWhiteSpace' set to `FALSE') *and* with `formatOutput' set to *`FALSE'* (with the opposite value of `formatOutput', the formatting should do it's work and you should not end up with just one line). But I haven't seen your source. Perhaps you had whitespace nodes containing no new-lines in your DOM?

As for the CAUTION about root element, I didn't see any problems with empty root element neither in shortened nor full form. What did you have in mind, when you said it `WORKS' or `DOES NOT WORK'?

down

xianrenb at gmail dot com ¶

12 years ago

If you want to save xhtml (in a string), you may try the following method:
<?php
    $doc = new DOMDocument('1.0');

    // ...

    $xhtml = (string) $doc->saveXML($doc->doctype);
    $xhtml .= "\n";
    $xhtml .= (string) $doc->saveXML($doc->documentElement);
?>

down

Alexander Fedulin ¶

10 years ago

As @fbernodi said earlier, there is a problem with saveXML of DOMNode when you have a number of defined namespaces. The simple solution for this:

<code>
   // $node is some node of some other document
   $temp_document = new DOMDocument('1.0', 'utf-8');
   $temp_document->appendChild($temp_document->importNode($node, true));
   echo $temp_document->saveXML();
</code>

down

fbernoldi at gmail dot com ¶

11 years ago

Hello,

I had an unexpected behavior in some parsing code, because of this saveXML method that is saving the tags without namespace specification. If you try to load into a DOMDocument a string saved from a DOMNode that has a referenced namespace but it the original document it was not defined in that element, you get a not well formed xml. In the example you can see the issue and a possible solution, the other solution may be add to the ChildElement node the namespace reference (<testNS:ChildElement testNS="http://example.org">), but in my scenario it was not needed.

<?php

//Test XML
$test_xml = 
"<?xml version=\"1.0\"?>
<testNS:RootNode xmlns:testNS=\"http://example.org\">
    <testNS:ChildElement>
        <testNS:AnotherChildElement>I'm a Another Child node.</testNS:AnotherChildElement>
    </testNS:ChildElement>
</testNS:RootNode>";

//We define our Test DOMDocument
$domDoc = new DOMDocument("1.0");
$domDoc->loadXML($test_xml);

//We use xpath to search ChildElement:
$domXPath = new DOMXPath($domDoc);
$domXPath->registerNamespace("testNS", "http://example.org");
$DOMNodeList_ChildElement = $domXPath->query("//testNS:RootNode/testNS:ChildElement");
$ChildElement = $DOMNodeList_ChildElement->item(0);

echo "Not usefull xml to load in another document:\n\n";
echo $domDoc->saveXML($ChildElement);

/* Output here:
 * 
 * Not usefull xml to load in another document:
 * 
 *  <testNS:ChildElement>
 *        <testNS:AnotherChildElement>I'm a Another Child node.</testNS:AnotherChildElement>
 *    </testNS:ChildElement>
 * 
 */

/**
 * Function to help us clone the element to another document.
 * @param DOMElement $node The node to clone.
 * @param DOMDocument $doc The document where we are going to reference the elements.
 * @return DOMElement The new cloned element without namespace.
 */
function cloneNode($node, $doc) {
    //Create new element with the original localName (w/o namespace)
    $nd = $doc->createElement($node->localName);

    //Clone attributes
    foreach($node->attributes as $value)
        $nd->setAttribute($value->localName, $value->value);

    //No more childs then we finish.
    if (!$node->childNodes)
        return $nd;
    //We have childs, add them
    foreach($node->childNodes as $child) {
        if ($child->nodeName=="#text") //Only needed to clone text nodes, i.e. text comments, spaces, tabs. etc.
            $nd->appendChild($doc->createTextNode($child->nodeValue));
        else
            $nd->appendChild(cloneNode($child, $doc)); //recursion to clone all children.
    }
    return $nd;
}

//New Document to reference the new node without namespaces
$domDoc2 = new DOMDocument("1.0");

//We clone this node taking out the namespace
$new_node = cloneNode($ChildElement, $domDoc2);

echo "\n\nWe can load this into a DOMDocument without problems:\n\n";
echo $domDoc2->saveXML($new_node);

/*
 * We can load this into a DOMDocument without problems:
 * 
 *    <ChildElement>
 *        <AnotherChildElement>I'm a Another Child node.</AnotherChildElement>
 *    </ChildElement>
 */

?>

down

Kriogen ¶

16 years ago

Create before test.xml with:
<?xml version="1.0" encoding="utf-8"?>
<Photos> 
</Photos>

and past after in your php-file:

<?php
$simp = simplexml_load_file('test.xml'); 
$node = $simp->addChild('home');
$node->addChild('mychild', 'insert text');
$s = simplexml_import_dom($simp);
$s->saveXML('test.xml');
?>

This code creating a child-nod in the root.
Owner http://www.mensfashion.ru

down

samstah at gmail dot com ¶

14 years ago

We discovered using DOMDocument::saveHTML() that it converts to HTML 4.01 compatible markup; rather than XHTML. The simple answer is to use saveXML() instead, although this adds the XML declaration to the top. 

To qjerry.com at gmail.com, thanks for the pointer below - but I think that the simplest way seems to be using:
<?php $domDocument->saveXML($domDocument->documentElement); ?>

Of course, if you're dealing with XHTML, this will strip any <!DOCTYPE> declarations in the document too.

down

shinsh at shinmugen dot net ¶

16 years ago

Be careful, this function has been changed in 5.2.6 version. Adding a required parameter which is not that required wasn't the most intelligent idea ever, especially for a function which is often used.

To fix your programs if you have an error, fill the first parameter like this:

$dom->saveXML($dom->documentElement);

Why didn't the devs simply implement this as optional parameter, fixing the default parameter as documentElement?

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Sander ¶

17 years ago

Note that for large DOM trees (tens of thousands of elements nested at least a few levels deep), setting formatOutput to true drives up memory usage to rather insane levels when you call saveXML(). (Tested with PHP 5.2.1) Pretty output is not worth that cost.

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Anonymous ¶

18 years ago

I used the function posted by "joe" but the following works to me for get the innerXML

<?php

$itemLeido = $XMLRespuesta->getElementsByTagName("articulos"); 

foreach($itemLeido as $node) {

    echo($node->ownerDocument->saveXML($node));

}

?>

down

nevyn at NOSPAM dot email dot PLEASE dot it ¶

17 years ago

A little function to get the full xml contents of a Xml node.

function innerXml($node)
{
    $out = $node->ownerDocument->saveXML($node);
    $re = "{^<(\\w*)(?:\\s*\\w+=(?:\"[^\"]*\"|\'[^\']*\'))*\\s*>(.*)</\\1>$}";
    preg_match($re, $out, $mat);
    return $mat[2];
}