DOMNodeList::item

(PHP 5, PHP 7, PHP 8)

DOMNodeList::item — Retrieves a node specified by index

Descrizione

public DOMNodeList::item(int $index): DOMElement|DOMNode|DOMNameSpaceNode|null

Retrieves a node specified by index within the DOMNodeList object.

Suggerimento

If you need to know the number of nodes in the collection, use the length property of the DOMNodeList object.

Elenco dei parametri

index: Index of the node into the collection.

Valori restituiti

The node at the indexth position in the DOMNodeList, or null if that is not a valid index.

Esempi

Example #1 Traversing all the entries of the table

<?php

$doc = new DOMDocument;
$doc->load('book.xml');

$items = $doc->getElementsByTagName('entry');

for ($i = 0; $i < $items->length; $i++) {
    echo $items->item($i)->nodeValue . "\n";
}

?>

Example #2 Accessing item with array syntax

<?php

for ($i = 0; $i < $items->length; $i++) {
    echo $items[$i]->nodeValue . "\n";
}

?>

Example #3 Traversing items with foreach

<?php

foreach ($items as $item) {
    echo $item->nodeValue . "\n";
}

?>

Il precedente esempio visualizzerà:

Title
Author
Language
ISBN
The Grapes of Wrath
John Steinbeck
en
0140186409
The Pearl
John Steinbeck
en
014017737X
Samarcande
Amine Maalouf
fr
2253051209

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User Contributed Notes 9 notes

down

vinyanov at poczta dot onet dot pl ¶

16 years ago

SimpleXML has its own SPL iterator. See http://www.php.net/~helly/php/ext/spl/classSimpleXMLIterator.html . But I guess that there are none for DOM nodes. By the way, two out of three implementations I found over the Net were not recursive, so I wrote my own. Here is the snippet:

<?php

class DOMNodeListIterator implements RecursiveIterator
{
    private
        $nodes,
        $offset;

    function __construct(DOMNodeList $nodes)
    {
        return $this -> nodes = $nodes;
    }
    
    function rewind()
    {
        return $this -> offset = 0;
    }
    
    function current()
    {
        return $this -> nodes -> item($this -> offset);
    }

    function key()
    {
        return $this -> current() -> nodeName;
    }
    
    function next()
    {
        return $this -> offset++;
    }
    
    function valid()
    {
        return $this -> offset < $this -> nodes -> length;
    }
    
    function hasChildren()
    {
        return isset($this -> current() -> childNodes -> length) && $this -> current() -> childNodes -> length > 0;
    }
    
    function getChildren()
    {
        return new self($this -> current() -> childNodes);
    }
}

?>

Remember to use RecursiveIteratorIterator::SELF_FIRST flag when you create your iterator iterator.

<?php

$iterator = new DOMNodeListIterator($document -> childNodes);
$iterator = new RecursiveIteratorIterator($iterator, RecursiveIteratorIterator::SELF_FIRST);

?>

Should work, has just few minutes though. :)

down

Geoffrey Thubron ¶

17 years ago

@ tfg_allardyce at gmail dot com

You could loop through the list backwards, that way, you are only ever taking off the last item from the list, and hence wont have disrupted the order.

down

Anonymous ¶

12 years ago

calling domnodelist->item($i) with an index $i greater than domnodelist->length - 1 , will return the entire document, will not produce an error, and will not circle back to the start of the list.

down

Nagy Attila ¶

13 years ago

DOMNodeList::item does not return in constant time!

If you need to iterate over large nodelist then you'd better use standard navigation.

Instead of:

<?php
foreach ($nodelist as $node) {
    // do something
}
?>

you could do:

<?php
$node = $parentnode->firstChild;

do {
    // do something
} while ($node = $node->nextSibling);
?>

down

jeffpuckett2 at gmail dot com ¶

8 years ago

DOMNodelist::item can return a DOMElement object, which extends DOMNode class. But it can also return a DOMText object.

<?php
$xml = '
<root>
  <node/>
  <node>
    <sub>more</sub>
  </node>
  <node>
    <sub>another</sub>
  </node>
  <node>value</node>
</root>
';

$doc = new DOMDocument();
$doc->loadXML($xml);

$items = $doc->documentElement->childNodes;
for ($i = 0; $i < $items->length; $i++)
  echo get_class($items->item($i)).PHP_EOL;
?>

Results in this output:

DOMText
DOMElement
DOMText
DOMElement
DOMText
DOMElement
DOMText
DOMElement
DOMText

down

Hayley Watson ¶

17 years ago

Keep in mind that DOMNodelists are "live" - changes to the document or node that the DOMNodelist was derived from will be reflected in the DOMNodelist. In other words, a list of a parent node's children will change if you change the parent's children!

down

olivier dot berger at it-sudparis dot eu ¶

16 years ago

It seems that with zend.ze1_compatibility_mode on, the only way to iterate over the items list is with :
for ($i = 0; $i < $nodeList->length; ++$i) {
    $nodeName = $nodeList->item($i)->nodeName;
    $nodeValue = $nodeList->item($i)->nodeValue;
}

As other attemps failed :

for ($i = 0; $i < $nodeList->length; ++$i) {
    $node = &$nodeList->item($i);
    $nodeName = $node->nodeName;
    $nodeValue = $node->nodeValue;
}

or :
foreach ($nodeList as $node) {
    echo $node->nodeName;
    echo $node->nodeValue;
}

down

james dot dunmore at gmai dot com ¶

17 years ago

tfg_allardyce at gmail dot com

I have had exactly this problem.

To rectify I've had to do this:
<?php
$old_element = $doc->getElementsByTagName('Element1')->item(0);
$new_element = $doc->createElement('NewElement1');

$old_element_childNodes = $old_element->childNodes;
$length = $old_element_childNodes->length;

for($i = 0; $i < $length; $i++)
{        
    $oldChildren_array[] = $old_element_childNodes->item($i);
}

foreach($oldChildren_array as $old_c)
{
    $new_element->appendChild($old_c);
}
?>

Rather than this:
(which I will bug report)
<?php
$old_element = $doc->getElementsByTagName('Element1')->item(0):
$new_element = $doc->createElement('NewElement1');

foreach($old_element->childNode as $node)
{
     $new_element->appendChild($node);
}

?>

Using the latter, randomally removes the children!

down

-1

oliver dot christen at camptocamp dot com ¶

17 years ago

NodeList are something annoying because you can't output the content with a simple print_r, so I did a little function that add all the node to a new empty DOMDocument and output it as a string.
Have fun.

<?php

public function domNodeList_to_string($DomNodeList) {
    $output = '';
    $doc = new DOMDocument;
    while ( $node = $DomNodeList->item($i) ) {
        // import node
        $domNode = $doc->importNode($node, true);
        // append node
        $doc->appendChild($domNode);
        $i++;
    }
    $output = $doc->saveXML();
    $output = print_r($output, 1);
    // I added this because xml output and ajax do not like each others
    $output = htmlspecialchars($output);
    return $output;
}

?>

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