CODEWITHSUNDEEP
phpxmldom
rr.
rr.

Reputation: 6634

PHP DOMElement::getElementsByTagName - Anyway to get just the immediate matching children?

is there a way to retrieve only the immediate children found by a call to DOMElement::getElementsByTagName? For example, I have an XML document that has a category element. That category element has sub category elements (which have the same structure), like:

<category>
    <id>1</id>
    <name>Top Level Category Name</name>
    <subCategory>
        <id>2</id>
        <name>Sub Category Name</name>
    </subCategory>
    ...
</category>

If I have a DOMElement representing the top level category, 

$topLevelCategoryElement->getElementsByTagName('id');

will return a list with the nodes for all 'id' elements, where I want just the one from the top level. Any way to do this outside of using XPath?

Upvotes: 10

Views: 8281

Answers (4)

MerlinTheMagic
MerlinTheMagic

Reputation: 605

You can compare elements using ===. This will avoid instantiating a Xpath object.

$dom = new DOMDocument();
$dom->loadXML($xmlString);

$return          = array();

//find your top level element
$topLevelElement = $dom->getElementsByTagName('category');
//find all `id` child elements recursively
$idElements      = $topLevelElement->getElementsByTagName('id');

if ($idElements->length > 0) {
    foreach ($idElements as $idElement) {
        if ($idElement->parentNode === $topLevelElement) {
            $return[]   = $idElement;
       }
    }
}

//$return now holds non nested child elements

Depending on the size of your XML document you might find Xpath performs better. However in terms of elegance this solution is cleaner.

Upvotes: -1

Kris
Kris

Reputation: 41827

Something like this should do

/**
 * Traverse an elements children and collect those nodes that
 * have the tagname specified in $tagName. Non-recursive
 *
 * @param DOMElement $element
 * @param string $tagName
 * @return array
 */
function getImmediateChildrenByTagName(DOMElement $element, $tagName)
{
    $result = array();
    foreach($element->childNodes as $child)
    {
        if($child instanceof DOMElement && $child->tagName == $tagName)
        {
            $result[] = $child;
        }
    }
    return $result;
}

edit: added instanceof DOMElement check

Upvotes: 13

Artefacto
Artefacto

Reputation: 97805

I'm afraid not. You'll have to iterate through the children or use XPath.

for ($n = $parent->firstChild; $n !== null; $n = $n->nextSibling) {
    if ($n instanceof DOMElement && $n->tagName == "xxx") {
        //...
    }
}

Example with XPath and your XML file:

$xml = ...;
$d = new DOMDocument();
$d->loadXML($xml);
$cat = $d->getElementsByTagName("subCategory")->item(0);
$xp = new DOMXpath($d);
$q = $xp->query("id", $cat); //note the second argument
echo $q->item(0)->textContent;

gives 2.

Upvotes: 18

Nick Bastin
Nick Bastin

Reputation: 31299

I don't use PHP, but if PHP actually implements the DOM API as specified the W3C, there is required to be a childNodes property on any Node object. You should be able to iterate over all of the direct children and test their tag name to see if they're the one you're looking for. Depending on what your tree looks like, this may be slower than getting all the elements by tag name and testing their tree position, or it may be significantly faster.

Upvotes: 2

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