Question

I thought to implement advanced commenting system in my website using PHP-MySql. I finally settled for a 3-level comment-reply system for this purpose.
Well, for that purpose I came across this article to implement the data-structure of the SQL database.

I planned to use nested set mdoel for the feature I want to use. The structure of the comments are like this-

<ul>
    <li>Parent comment</li>
        <ul>
            <li>First reply of parent comment</li>
            <ul>
                <li>reply of the previous reply</li>
                   <ul>
                       <li>reply of the previous reply</li>
                       <li>another reply of the previous reply</li>
                   </ul>
                <li>another reply of the previous comment</li>
             </ul>
             <li>second reply of the parent comment</li>
        </ul>
</ul>

For this type of structure, I have been playing around with PHP to show the query detecting the parents and its child uniquely(for fetching user details associated with each comment) and produce the output in the manner if shown above. Do anyone have idea how to do it. Please help me out.

EDIT :

I have a seperate user table in SQL linked to the comment table as user.id=comment.id. So considering this, what would be the recommended approach to detect user activity for each comment? I mean, for ex- I want to fetch user name and email for a sub-comment of parent comment 2. Hoow could it be done?

Answer 1

Use the query from “Finding the Depth of the Nodes”, and this PHP code will create the nested lists.

$cur_depth = -1;
while ($row = mysqli_fetch_assoc($query)) { // Loop through results of query
  if ($row['depth'] > $cur_depth) {
    echo "<ul>\n";
    $cur_depth = $row['depth'];
  }
  else while ($cur_depth > $row['depth']) {
    echo "</ul>\n";
    $cur_depth--;
  }
  echo "<li>" . $row['comment'] . "</li>\n";
}
while ($cur_depth > -1) {
  echo "</ul>\n";
  $cur_depth--;
}