Remove parent element, keep all inner children in

2019-02-12 16:34发布

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问题:

I'm manipulating a short HTML snippet with XPath; when I output the changed snippet back with $doc->saveHTML(), DOCTYPE gets added, and HTML / BODY tags wrap the output. I want to remove those, but keep all the children inside by only using the DOMDocument functions. For example:

$doc = new DOMDocument();
$doc->loadHTML('<p><strong>Title...</strong></p>
<a href="http://www....."><img src="http://" alt=""></a>
<p>...to be one of those crowning achievements...</p>');
// manipulation goes here
echo htmlentities( $doc->saveHTML() );

This produces:

<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN" ...>
<html><body>
<p><strong>Title...</strong></p>
<a href="http://www....."><img src="http://" alt=""></a>
<p>...to be one of those crowning achievements...</p>
</body></html>

I've attempted some of the simple tricks, such as:

# removes doctype
$doc->removeChild($doc->firstChild);

# <body> replaces <html>
$doc->replaceChild($doc->firstChild->firstChild, $doc->firstChild);

So far that only removes DOCTYPE and replaces HTML with BODY. However, what remains is body > variable number of elements at this point.

How do I remove the <body> tag but keep all of its children, given that they will be structured variably, in a neat - clean way with PHP's DOM manipulation?

回答1:

UPDATE

Here's a version that doesn't extend DOMDocument, though I think extending is the proper approach, since you're trying to achieve functionality that isn't built-in to the DOM API.

Note: I'm interpreting "clean" and "without workarounds" as keeping all manipulation to the DOM API. As soon as you hit string manipulation, that's workaround territory.

What I'm doing, just as in the original answer, is leveraging DOMDocumentFragment to manipulate multiple nodes all sitting at the root level. There is no string manipulation going on, which to me qualifies as not being a workaround.

$doc = new DOMDocument();
$doc->loadHTML('<p><strong>Title...</strong></p><a href="http://www....."><img src="http://" alt=""></a><p>...to be one of those crowning achievements...</p>');

// Remove doctype node
$doc->doctype->parentNode->removeChild($doc->doctype);

// Remove html element, preserving child nodes
$html = $doc->getElementsByTagName("html")->item(0);
$fragment = $doc->createDocumentFragment();
while ($html->childNodes->length > 0) {
    $fragment->appendChild($html->childNodes->item(0));
}
$html->parentNode->replaceChild($fragment, $html);

// Remove body element, preserving child nodes
$body = $doc->getElementsByTagName("body")->item(0);
$fragment = $doc->createDocumentFragment();
while ($body->childNodes->length > 0) {
    $fragment->appendChild($body->childNodes->item(0));
}
$body->parentNode->replaceChild($fragment, $body);

// Output results
echo htmlentities($doc->saveHTML());

ORIGINAL ANSWER

This solution is rather lengthy, but it's because it goes about it by extending the DOM in order to keep your end code as short as possible.

sliceOutNode is where the magic happens. Let me know if you have any questions:

<?php

class DOMDocumentExtended extends DOMDocument
{
    public function __construct( $version = "1.0", $encoding = "UTF-8" )
    {
        parent::__construct( $version, $encoding );

        $this->registerNodeClass( "DOMElement", "DOMElementExtended" );
    }

    // This method will need to be removed once PHP supports LIBXML_NOXMLDECL
    public function saveXML( DOMNode $node = NULL, $options = 0 )
    {
        $xml = parent::saveXML( $node, $options );

        if( $options & LIBXML_NOXMLDECL )
        {
            $xml = $this->stripXMLDeclaration( $xml );
        }

        return $xml;
    }

    public function stripXMLDeclaration( $xml )
    {
        return preg_replace( "|<\?xml(.+?)\?>[\n\r]?|i", "", $xml );
    }
}

class DOMElementExtended extends DOMElement
{
    public function sliceOutNode()
    {
        $nodeList = new DOMNodeListExtended( $this->childNodes );
        $this->replaceNodeWithNode( $nodeList->toFragment( $this->ownerDocument ) );
    }

    public function replaceNodeWithNode( DOMNode $node )
    {
        return $this->parentNode->replaceChild( $node, $this );
    }
}

class DOMNodeListExtended extends ArrayObject
{
    public function __construct( $mixedNodeList )
    {
        parent::__construct( array() );

        $this->setNodeList( $mixedNodeList );
    }

    private function setNodeList( $mixedNodeList )
    {
        if( $mixedNodeList instanceof DOMNodeList )
        {
            $this->exchangeArray( array() );

            foreach( $mixedNodeList as $node )
            {
                $this->append( $node );
            }
        }
        elseif( is_array( $mixedNodeList ) )
        {
            $this->exchangeArray( $mixedNodeList );
        }
        else
        {
            throw new DOMException( "DOMNodeListExtended only supports a DOMNodeList or array as its constructor parameter." );
        }
    }

    public function toFragment( DOMDocument $contextDocument )
    {
        $fragment = $contextDocument->createDocumentFragment();

        foreach( $this as $node )
        {
            $fragment->appendChild( $contextDocument->importNode( $node, true ) );
        }

        return $fragment;
    }

    // Built-in methods of the original DOMNodeList

    public function item( $index )
    {
        return $this->offsetGet( $index );
    }

    public function __get( $name )
    {
        switch( $name )
        {
            case "length":
                return $this->count();
            break;
        }

        return false;
    }
}

// Load HTML/XML using our fancy DOMDocumentExtended class
$doc = new DOMDocumentExtended();
$doc->loadHTML('<p><strong>Title...</strong></p><a href="http://www....."><img src="http://" alt=""></a><p>...to be one of those crowning achievements...</p>');

// Remove doctype node
$doc->doctype->parentNode->removeChild( $doc->doctype );

// Slice out html node
$html = $doc->getElementsByTagName("html")->item(0);
$html->sliceOutNode();

// Slice out body node
$body = $doc->getElementsByTagName("body")->item(0);
$body->sliceOutNode();

// Pick your poison: XML or HTML output
echo htmlentities( $doc->saveXML( NULL, LIBXML_NOXMLDECL ) );
echo htmlentities( $doc->saveHTML() );


回答2:

saveHTML can output a subset of document, meaning we can ask it to output every child node one by one, by traversing body.

$doc = new DOMDocument();
$doc->loadHTML('<p><strong>Title...</strong></p>
<a href="http://google.com"><img src="http://google.com/img.jpeg" alt=""></a>
<p>...to be one of those crowning achievements...</p>');
// manipulation goes here

// Let's traverse the body and output every child node
$bodyNode = $doc->getElementsByTagName('body')->item(0);
foreach ($bodyNode->childNodes as $childNode) {
  echo $doc->saveHTML($childNode);
}

This might not be a most elegant solution, but it works. Alternatively, we can wrap all children nodes inside some container element (say a div) and output only that container (but container tag will be included in the output).



回答3:

Here how I've done it:

-- Quick helper function that gives you HTML contents for specific DOM element

function nodeContent($n, $outer=false) {
   $d = new DOMDocument('1.0');
   $b = $d->importNode($n->cloneNode(true),true);
   $d->appendChild($b); $h = $d->saveHTML();
   // remove outter tags
   if (!$outer) $h = substr($h,strpos($h,'>')+1,-(strlen($n->nodeName)+4));
   return $h;
}

-- Find body node in your doc and get its contents

$query = $xpath->query("//body")->item(0);
if($query)
{
    echo nodeContent($query);
}

UPDATE 1:

Some extra info: Since PHP/5.3.6, DOMDocument->saveHTML() accepts an optional DOMNode parameter similarly to DOMDocument->saveXML(). You can do 

$xpath = new DOMXPath($doc);
$query = $xpath->query("//body")->item(0);
echo $doc->saveHTML($query);

for others, the helper function will help



回答4:

You have 2 ways to accomplish this:

$content = substr($content, strpos($content, '<html><body>') + 12); // Remove Everything Before & Including The Opening HTML & Body Tags.
$content = substr($content, 0, -14); // Remove Everything After & Including The Closing HTML & Body Tags.

Or even better is this way:

$dom->normalizeDocument();
$content = $dom->saveHTML();


标签： php xpath domdocument
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