(PHP 5, PHP 7, PHP 8)
DOMNode::insertBefore — Adds a new child before a reference node
This function inserts a new node right before the reference node. If you plan to do further modifications on the appended child you must use the returned node.
When using an existing node it will be moved.
nodeThe new node.
child
The reference node. If not supplied, node is
appended to the children.
The inserted node or false on error.
DOM_NO_MODIFICATION_ALLOWED_ERRRaised if this node is readonly or if the previous parent of the node being inserted is readonly.
DOM_HIERARCHY_REQUEST_ERR
Raised if this node is of a type that does not allow children of the
type of the node node, or if the node to
append is one of this node's ancestors or this node itself.
DOM_WRONG_DOCUMENT_ERR
Raised if node was created from a different
document than the one that created this node.
DOM_NOT_FOUND_ERR
Raised if child is not a child of this node.
1st argument) a node to insert 2nd argument) a reference node - this is the node that the new node will be inserted beforeThe trick to using this method is that the OBJECT on which you actually CALL the insertBefore() method is actually the PARENT node of the reference node! INCORRECT:$DOMNode_refNode->insertBefore($DOMNode_newNode, $DOMNode_refNode); CORRECT:$DOMNode_refNode->parentNode->insertBefore($DOMNode_newNode, $DOMNode_refNode);Note that supplying the same node for $newnode and $refnode leads to an E_WARNING ("Couldn't add newnode as the previous sibling of refnode"). For example imagine one wanted to make $newnode the first child of its parent by doing:<?php$firstSibling = $newnode->parentNode->firstChild;// Bad:$newnode->parentNode->insertBefore( $newnode, $firstSibling );?>This would generate a warning if it already was the first child of its parent, since $newnode and $firstSibling are identical. Easy to work around though:<?php$firstSibling = $newnode->parentNode->firstChild;// Better:if( $newnode !== $firstSibling ) { $newnode->parentNode->insertBefore( $newnode, $firstSibling );}?>example to insert <newnode/> between <chid1/> and <child2/><?xml version="1.0" encoding="ISO-8859-1" ?> <root> <parent> <child nr="1"/> <child nr="2"/> </parent> </root> <?php $xml_src = 'test.xml'; // XPath-Querys $parent_path = "//parent"; $next_path = "//parent/child[@nr='2']"; // Create a new DOM document $dom = new DomDocument(); $dom->load($xml_src); // Find the parent node $xpath = new DomXPath($dom); // Find parent node $parent = $xpath->query($parent_path); // new node will be inserted before this node $next = $xpath->query($next_path); // Create the new element $element = $dom->createElement('newnode'); // Insert the new element $parent->item(0)->insertBefore($element, $next->item(0)); echo $dom->saveXML(); ?>Sorry, my previous posting worked only for the top node. Here the corrected version, which will work for any node:XML----<?xml version="1.0"?><contacts> <person>Adam</person> <person>Eva</person> <person>Thomas</person></contacts>PHP---<?php// load XML, create XPath object$xml = new DomDocument();$xml->preserveWhitespace = false;$xml->load('contacts.xml');$xpath = new DOMXPath($xml);// get node eva, which we will append to$eva = $xpath->query('/contacts/person[.="Eva"]')->item(0);// create node john$john = $xml->createElement('person', 'John');// insert john after eva// "in eva's parent node (=contacts) insert// john before eva's next node"// this also works if eva would be the last node$eva->parentNode->insertBefore($john, $eva->nextSibling);// show resultheader('Content-Type: text/plain');print $xml->saveXML();?>Result------<?xml version="1.0"?><contacts> <person>Adam</person> <person>Eva</person><person>John</person> <person>Thomas</person></contacts>