Error passing post_content to function

Question

The purpose of this function is to simply wrap the first occurrence of the keyword in bold tags. I'm getting an error on the line marked below.

Warning: DOMDocument::loadHTML() [domdocument.loadhtml]: error parsing attribute name in Entity, line: 4 in C:\xampplite\htdocs\testsite\wp-content\plugins\mylugin\test.php on line 40

Is this the correct way to pass the post_content object?

add_filter('wp_insert_post_data', 'my_bold_keyword' );
function my_bold_keyword($content){
  $myKeyword = "test 123";
  $d = new DOMDocument();
  $d->loadHTML($content['post_content']); //ERROR OCCURS HERE
  $x = new DOMXpath($d);
  $Matches = $x->query("//text()[contains(.,$myKeyword) and not(ancestor::h1) and not(ancestor::h2) and not(ancestor::h3) and not(ancestor::h4) and not(ancestor::h5) and not(ancestor::h6)]");
  if($Matches && $Matches->length > 0){
    $myText = $Matches->item(0);
    // need to wrap #myText in <b> wrapper
  }
  return $content;
}

Answer 1

Hi @Scott B:

Here's a modified version of what you have that resolves the error (although the XPath does not match; I'm not an XPath guru so can't help with the proper XPath syntax):

add_filter('wp_insert_post_data', 'my_bold_keyword', 10, 2 );
function my_bold_keyword( $data, $postarr ) {
  $myKeyword = "test 123";
  $d = new DOMDocument();
  $d->loadHTML($postarr['post_content']); //ERROR NO LONGER OCCURS HERE
  $x = new DOMXpath($d);
  $Matches = $x->query("//text()[contains(.,$myKeyword) and not(ancestor::h1) and not(ancestor::h2) and not(ancestor::h3) and not(ancestor::h4) and not(ancestor::h5) and not(ancestor::h6)]");
  if($Matches && $Matches->length > 0){
    $myText = $Matches->item(0);
    // need to wrap #myText in <b> wrapper
  }
  return $content;
}

P.S. About that PhpStorm... '-)