DOMNode::insertBefore

(PHP 5, PHP 7, PHP 8)

DOMNode::insertBefore — Adds a new child before a reference node

说明

public DOMNode::insertBefore(DOMNode $node, ?DOMNode $child = null): DOMNode|false

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.

参数

node: The new node.
child: The reference node. If not supplied, node is appended to the children.

返回值

The inserted node.

错误／异常

DOM_NO_MODIFICATION_ALLOWED_ERR: Raised 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: Raised if child is not a child of this node.

参见

DOMNode::appendChild() - Adds new child at the end of the children

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User Contributed Notes 5 notes

down

Jerry Ellis ¶

17 years ago


1st argument) a node to insert 
2nd argument) a reference node - this is the node that the new node will be inserted before

The 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);

down

jarry1250 at gmail dot com ¶

7 years ago


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 );
}
?>

down

jg at handcode dot de ¶

16 years ago


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(); 

?>

down

-3

DrTebi at Yahoo ¶

14 years ago


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 result
header('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>

down

-5

justin at redwiredesign dot com ¶

15 years ago


The previous example is incorrect, and causes a DOM_NOT_FOUND error, as the child nodes are not direct descendants of the root node.

Therefore, the line:

$parent_path = "/root";

needs to change to:

$parent_path = "/root/parent";

or 

$parent_path = "//parent";

for this example to work

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官方地址：https://www.php.net/manual/en/domnode.insertbefore.php

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DOMNode::insertBefore

说明

参数

返回值

错误／异常

参见

User Contributed Notes 5 notes