Setting nodeValue of a DOMelement : error :Trying to get property of non-object

Question

When running this php script :

$doc = new DOMDocument();
    $doc->loadHTMLFile("some_url.html");
    $ele1 = $doc->getElementById ( "coupon" );
    if($ele1->length){
    $doc->getElementById ( "coupon" )->item(0)->nodeValue =$result["affiliate_name"] ;}

I get : Trying to get property of non-object in the last line if it's not the right way to do it, how can I set the text of tag that I must extract usig its Id.

here is my some_url.html :

  <div class="panel panel-success">
    <div class="panel-heading">
      <h3 id="coupon" class="panel-title">Coupon name 1</h3>
    </div>
<p id="coupon_id" hidden>coupon id</p>
    <div id="counter-up" class="panel-body">
      0
    </div>
  </div>

Thank you

Answer 1

According to the official documentation, getElementById() returns a single DOMElement , which extends DOMNode , which in turn has the $nodeValue field you are trying to change. A DOMNode is not a DOMNodeList , so it has neither the $length field nor the item() method. Because of that, you aren't supposed to call item() on that element, you can directly manipulate its $nodeValue . To find out whether such element exists, simply test the result of getElementById() for equality with NULL (or use if ($element) as a shorthand). Complete code would look as follows:

$doc = new DOMDocument();
$doc->loadHTMLFile("some_url.html");
$ele1 = $doc->getElementById("coupon");
if ($ele1) $ele1->nodeValue = $result["affiliate_name"];

Sources:
http://pl1.php.net/manual/en/domdocument.getelementbyid.php
http://pl1.php.net/manual/en/class.domelement.php
http://pl1.php.net/manual/en/class.domnode.php