Preg_replace content with mysql query

I’m creating a replacement function. I have data in a db with a field ‘content’ that returns the content for a page. In that content I have a url tag like <a href="[2]">title</a>. The number between the [brackets] is the page_id of my pages table.

I have a function called replaceContent:

function replaceContent($content,$mysqli){
    $search = "/([)(.*?)(])/";
 
    $newContent = preg_replace($search,makeUrl('$2',$mysqli),$content);
    return $newContent;
}

in that function I have a function called makeUrl:

function makeUrl($id,$mysqli){
    $query = "SELECT url FROM pages WHERE id = '".$id."' ";
    $result = $mysqli->query($query);
    $data = $result -> fetch_assoc();
    return $data['url'];
}

What I tried:

• When I call the function makeUrl(2,$mysqli) standalone, it works fine and returns the url.
• When I change the return in the makeUrl function with ‘abc $id’ the replaceContent function replaces the url with ‘abc 2’

But together I get a blank return…

Anybody knows what I’m doing wrong? Thanks a lot

Answer

Group references (e.g. $2) are parsed in any replacement strings, but you’re replacing with the return value of a function. So you’re litereally passing along $2 as the argument, not 2.

Instead, feed the matches to a callback.

preg_replace_callback($search, function($match) use($mysqli) {
    return makeUrl($match[2], $mysqli)
}, $content)