Member Avatar for flynismo

Hi all,

I'm currently putting together a search engine for my website, and so far, everything is going pretty smoothly.

The only thing left that I would like to do is when the search results are displayed, I want to be able to highlight the search term entered in the page that displays the results of the query.

For example, if I search for the term "dog grooming", here is a possible result, with the term "dog grooming" bolded:

"Acme Dog Grooming offers the finest and most affordable dog grooming service in your area. Contact us at (555)123-4567 for more details".

Below is a class that I am using, and would like to know how I can modify it so that I can highlight the search term entered. In the code below, the variable $_POST['searchbox'] is the search term being entered and what I'd like to hightlight.

class SearchAboutMe extends Search{
        public function __construct()
        {

            $db = new PDO(### Database connection details ###);
            $q = $db->prepare(" SELECT something FROM somewhere WHERE somecolumn LIKE ? ");
            $q->execute(array('%'.$_POST['searchbox'].'%')); ### Here the query is being executed
            $q->setFetchMode(PDO::FETCH_ASSOC);

            $r = $q->fetch();
            $this->username = $r['username'];
            $this->city = $r['city'];
            $this->state = ucwords(strtolower($r['state']));
            $this->zipcode = $r['zip'];
            $this->info = $r['info'];

            ### Here is where the search results get displayed

            $count = $q->rowCount();
            if($count >= 1){

            ### Results were found for search term, and the search term is contained somewhere inside
            ### the $this->info property

                echo "<div class=results>
                      <a href=". $this->username .">" . $this->info . "</a></div>";
            }else{
                 $count == 0;
                 echo "<div class=\"alert alert-error\"><button type=\"button\" class=\"close\" data-dismiss=\"alert\">×</button>No results found for: <strong> " . $_POST['searchbox'] . "</strong></div>";
            }
        }
}

So in the example code above, the property $this->info will contain the search term ($_POST['searchbox']). How can I extract the search term from it?

Thanks very much for any help!

Edited by flynismo
  • 2 Contributors
  • 4 Replies
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  • 27 Minutes Discussion Span
  • Latest Post Latest Post by flynismo

Dani AI

Generated

Good quick fix from — the simple replace that implemented is a perfectly fine, minimal solution for exact, case-sensitive matches. It’s worth calling out the common pitfalls you’ll hit as you make the search UI more robust: case-insensitivity, phrase vs. token matching, accidental highlighting inside HTML tags or attributes, multibyte (UTF-8) text, overlapping/partial matches (e.g. cat vs caterpillar) and XSS/sanitization concerns when results contain user-supplied HTML.

If you want something more robust but still straightforward, split the result HTML into “tag” vs “text” chunks, only run replacements on text chunks, build a safe regex from the search terms (use preg_quote), sort terms by length (longest first) to avoid partial matches, and use the i + u flags for case-insensitive Unicode matching. Example function (works on HTML or on escaped/plain text):

function highlight_terms_in_html($html, $query){
    $query = trim($query);
    if ($query === '') return $html;

    $terms = preg_split('/\s+/u', $query, -1, PREG_SPLIT_NO_EMPTY);
    usort($terms, function($a,$b){ return mb_strlen($b,'UTF-8') - mb_strlen($a,'UTF-8'); });
    $pattern = '/(' . implode('|', array_map(function($t){ return preg_quote($t,'/'); }, $terms)) . ')/iu';

    $parts = preg_split('/(<[^>]+>)/', $html, -1, PREG_SPLIT_DELIM_CAPTURE);
    $skipTags = array('script','style','noscript'); $skip = false; $openTag = '';
    foreach ($parts as $i => $part) {
        if ($part === '') continue;
        if ($part[0] === '<') {
            if (preg_match('/^<\s*\/\s*([a-z0-9:-]+)/i',$part,$m)) {
                $tag = strtolower($m[1]); if ($skip && $tag === $openTag) { $skip = false; $openTag = ''; }
            } elseif (preg_match('/^<\s*([a-z0-9:-]+)/i',$part,$m)) {
                $tag = strtolower($m[1]); if (in_array($tag,$skipTags)) { $skip = true; $openTag = $tag; }
            }
            continue;
        }
        if ($skip) continue;
        $parts[$i] = preg_replace_callback($pattern, function($m){ return '<strong>' . $m[0] . '</strong>'; }, $part);
    }
    return implode('', $parts);
}

Usage notes: if $this->info is plain text, echo highlight_terms_in_html(htmlspecialchars($this->info, ENT_QUOTES, 'UTF-8'), $_POST['searchbox']);. If it contains HTML you want to preserve, sanitize allowed tags first (e.g. HTMLPurifier or an allowlist) then pass the raw HTML into the function. For older PHP (pre-5.3) replace closures with named callbacks. Consider using <mark> or a .highlight span for styling instead of <strong> if you want purely visual emphasis.

Recommended Answers

All 4 Replies

Member Avatar for pritaeas

I suggest you do a str_replace, replacing the searched text with the searched text pre-/appended with the bold tag, in the info field.

Member Avatar for flynismo

Thank you pritaeas, let me make sure I am understanding correctly.

Are you are suggesting that I do something like this:

str_replace($_POST['searchbox'],$this->info,"<strong>" . $_POST['searchbox'] . "</strong>")

Member Avatar for flynismo

Nevermind, got it working thanks to pritaeas for the idea...you are awesome!

Member Avatar for flynismo

Just in case this might help someone else, here is the final code:

I replaced this in the original code:

 if($count >= 1){
### Results were found for search term, and the search term is contained somewhere inside
### the $this->info property
echo "<div class=results>
<a href=". $this->username .">" . $this->info . "</a></div>";
}

with this below:

        if($count >= 1){
            $result = str_replace($_POST['searchbox'], "<strong>" . $_POST['searchbox'] . "</strong>", $this->info);
            echo $result;
        }
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