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PHP : Function Reference : DOM Functions : DOMDocument->getElementById()

DOMDocument->getElementById()

Searches for an element with a certain id ()

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DOMDocument {
  DOMElement getElementById(string elementId);
}

This function is similar to DOMDocument->getElementsByTagName() but searches for an element with a given id.

For this function to work, you will need either to set some ID attributes with DOMElement->setIdAttribute() or a DTD which defines an attribute to be of type ID. In the later case, you will need to validate your document with DOMDocument->validate() or DOMDocument->validateOnParse before using this function.

Parameters

elementId: The unique id value for an element.

Return Values

Returns the DOMElement or NULL if the element is not found.

Examples

Example 519. DOMDocument->getElementById() Example

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<?php


$doc = new DomDocument;

// We need to validate our document before refering to the id
$doc->validateOnParse = true;
$doc->Load('book.xml');


echo "The element whose id is books is: " . $doc->getElementById('books')->tagName . "\n";

?>

The above example will output:

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The element whose id is books is: chapter

See Also

DOMDocument->getElementsByTagName()

Related Examples ( Source code ) » dom domdocument getelementbyid

Examples ( Source code ) » Example of DOMDocument->normalize()

Examples ( Source code ) » DOMDocument->getElementsByTagName() Examples

Code Examples / Notes » dom domdocument getelementbyid

tangui dot le-pense

Validating a document from a DTD so as to use getElementById is sometimes impossible (for example when the head and body elements are not included yet in a XHtml document : the validation failed). Fortunately, xml:id is supported by this function :) That may be useful. http://www.w3.org/TR/xml-id/

simon

SAVE YOURSELF A MAJOR HEADACHE AND A LOT OF SEARCHING THROUGH DOCUMENTATION - Instead of using $object->setAttribute('id', 'id_name_here') USE THIS: $object->setAttribute('xml:id', 'id_name_here') Then, to get the node value: $domDocumentObject->getElementById('id_name_here'); The xml:id attribute should AUTOMATICALLY be defined!! Woohoo! That was easy......

bart

It seems getElementById works fine without setting validateOnParse to true. Which is nice since setting this to true caused some performance problems with my script.

jonbarnett

If your XML document does not have a DTD that defines the "id" attribute as an ID, then the easiest thing to do is to use XPath->query() to find an element that matches "//[@id='x']"

20-dec-2005 03:04

If you're trying to use getElementById with a xml file validated on a xsd file you must first use the schemaValidate function or getElementById will return null Example: $dom = new DomDocument(); $dom->load("users.xml"); $dom->schemaValidate("users.xsd"); $curruser = $dom->getElementById($user->name);

dagfinn

Here is an updated link to the getElementById() pitfalls page: http://wiki.flux-cms.org/display/BLOG/GetElementById+Pitfalls

chregu

http://wiki.bitflux.org/GetElementById_Pitfalls has an overview, of how to make getElementById work with aribtrary XML documents.

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DOMAttr->__construct()
DOMAttr->isId()
DOMCharacterData->appendData()
DOMCharacterData->deleteData()
DOMCharacterData->insertData()
DOMCharacterData->replaceData()
DOMCharacterData->substringData()
DOMComment->__construct()
DOMDocument->__construct()
DOMDocument->createAttribute()
DOMDocument->createAttributeNS()
DOMDocument->createCDATASection()
DOMDocument->createComment()
DOMDocument->createDocumentFragment()
DOMDocument->createElement()
DOMDocument->createElementNS()
DOMDocument->createEntityReference()
DOMDocument->createProcessingInstruction()
DOMDocument->createTextNode()
DOMDocument->getElementById()
DOMDocument->getElementsByTagName()
DOMDocument->getElementsByTagNameNS()
DOMDocument->importNode()
DOMDocument->load()
DOMDocument->loadHTML()
DOMDocument->loadHTMLFile()
DOMDocument->loadXML()
DOMDocument->normalizeDocument()
DOMDocument->registerNodeClass()
DOMDocument->relaxNGValidate()
DOMDocument->relaxNGValidateSource()
DOMDocument->save()
DOMDocument->saveHTML()
DOMDocument->saveHTMLFile()
DOMDocument->saveXML()
DOMDocument->schemaValidate()
DOMDocument->schemaValidateSource()
DOMDocument->validate()
DOMDocument->xinclude()
DOMDocumentFragment->appendXML()
DOMElement->__construct()
DOMElement->getAttribute()
DOMElement->getAttributeNode()
DOMElement->getAttributeNodeNS()
DOMElement->getAttributeNS()
DOMElement->getElementsByTagName()
DOMElement->getElementsByTagNameNS()
DOMElement->hasAttribute()
DOMElement->hasAttributeNS()
DOMElement->removeAttribute()
DOMElement->removeAttributeNode()
DOMElement->removeAttributeNS()
DOMElement->setAttribute()
DOMElement->setAttributeNode()
DOMElement->setAttributeNodeNS()
DOMElement->setAttributeNS()
DOMElement->setIdAttribute()
DOMElement->setIdAttributeNode()
DOMElement->setIdAttributeNS()
DOMEntityReference->__construct()
DOMImplementation->__construct()
DOMImplementation->createDocument()
DOMImplementation->createDocumentType()
DOMImplementation->hasFeature()
DOMNamedNodeMap->getNamedItem()
DOMNamedNodeMap->getNamedItemNS()
DOMNamedNodeMap->item()
DOMNode->appendChild()
DOMNode->cloneNode()
DOMNode->hasAttributes()
DOMNode->hasChildNodes()
DOMNode->insertBefore()
DOMNode->isDefaultNamespace()
DOMNode->isSameNode()
DOMNode->isSupported()
DOMNode->lookupNamespaceURI()
DOMNode->lookupPrefix()
DOMNode->normalize()
DOMNode->removeChild()
DOMNode->replaceChild()
DOMNodelist->item()
DOMProcessingInstruction->__construct()
DOMText->__construct()
DOMText->isWhitespaceInElementContent()
DOMText->splitText()
DOMXPath->__construct()
DOMXPath->evaluate()
DOMXPath->query()
DOMXPath->registerNamespace()
dom_import_simplexml

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