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    DOMNode::insertBefore

    (PHP 5, PHP 7, PHP 8)

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

    Description

    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.

    Parameters

    node

    The new node.

    child

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

    Return Values

    The inserted node or false on error.

    Errors/Exceptions

    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.

    See Also

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    User Contributed Notes 5 notes

    up
    7
    Jerry Ellis
    19 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);
    up
    5
    jarry1250 at gmail dot com
    9 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 );
    }
    ?>
    up
    6
    jg at handcode dot de
    19 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();

    ?>
    up
    -3
    DrTebi at Yahoo
    17 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>
    up
    -5
    justin at redwiredesign dot com
    17 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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