Array inside array (comment system with 2 levels)

Question

I have a comment system on 2 levels (like Blizzard http://eu.battle.net/sc2/en/blog/7935264/#c-7257875753), it's working fine but my code is a bit dirty :

// $datacoms array from mysql_query 
foreach($datacoms as $com){
 if(!$com->parent_id){
 $level_id = $com->id;
 // include the view (display the comment)
 foreach($datacoms as $com){
 if($com->parent_id == $level_id){
 // include the view (display the comment)
 }
 }
 }
}

Any better way to do it ?

Answer 1

Depends on how your data is modeled. I dont know that, but I can assume that you use three relational tables. Something along these lines:

Post [parent]
+-------------+---------+
| Field | Type |
+-------------+---------+
| id | int |
| value | varchar |
+-------------+---------+
Comment [parent-child]
+-------------+---------+
| Field | Type |
+-------------+---------+
| id | int |
| foreign_key | int |
| value | varchar |
+-------------+---------+
Comment->Comment [child]
+-------------+---------+
| Field | Type |
+-------------+---------+
| id | int |
| foreign_key | int |
| value | varchar |
+-------------+---------+

You are looking to potentially run three queries. An easy fix would be to add a has_children field to each parent table. With that you would save a potential checkup and easily release some complexity in the PHP loop.

 [parent-child]
 +--------------+---------+
 | Field | Type |
 +--------------+---------+
 | id | int |
 | foreign_key | int |
 | has_children | bool | <===
 | value | varchar |
 +--------------+---------+

I can provide the PHP code if you like, but I'm assuming that you get the general idea.