Display hierarchical data

Question

I am playing around with a code example i found here about 'tree menu' and wanted to make this question.

function tree($id)
{
$query = "SELECT `name`,`id` from `table` WHERE `id_parrent` = '$id'";
$result = mysql_query($query);
 if(mysql_num_rows($result) != 0)
   {
        echo "<ul>";
        while($row = mysql_fetch_array($result))
        {             
             echo "<li>",$row[name],"</li>";
             tree($row[id]);
        }
        echo "</ul>";
   }
}

what if i want to display items in a way like this:

<ul>
<li>item 1</li>
<li>item 2</li>
  <li style="padding-left:10px;">item 3-has parent 2</li>
   <li style="padding-left:20px;">item 4-has parent 3</li>
  <li style="padding-left:10px;">item 5-has parent 2</li>
<li>item 6</li>
</ul>

My main problem is to find the level somehow so that i could multiply level*padding and create my list. Any suggestions would be appreciated.

Answer 1

You need your tree function to track the level, and then apply padding if the level is greater than 1.

function tree($id, $level=1) {
    $query = "SELECT `name`,`id` from `table` WHERE `id_parrent` = '$id'";
    $result = mysql_query($query);
    if (mysql_num_rows($result) != 0) {
     echo "<ul>";
     while ($row = mysql_fetch_array($result)) {
         if ($level == 1)
             echo "<li>" . $row[name] . "</li>";
         else
          echo "<li style='padding-left: " + (($level - 1) * 10) + "px;'>" . $row[name] . "</li>";
         tree($row[id], $level + 1);
     }
     echo "</ul>";
    }
}

Answer 2

I have a store with recursive inventory categories similar to what you're doing. Here's the code I wrote to present it as an unordered list (slightly modified for this example). Hope it helps!

  /**
   * Inventory Categories
   */
  function inventoryCategories() {

    $result = mysql_query("select * from store_inventorycategory");

    $rows = array();

    while ($row = mysql_fetch_array($result)) {
      $p = $row['parent_category_id'];
      $id = $row['id'];
      $rows[$id] = array('id'=>$id, 'parent'=>$p, 'title'=>$row['title'], 'children'=>array());
    }

    foreach ($rows as $k=>&$v) {
      if ($v['parent'] == $v['id']) continue;
      $rows[$v['parent']]['children'][] = &$v;
    }

    array_splice($rows,1);

    echo '<ul>';
    recurseInventoryCategory($rows[0]);
    echo '</ul>';   
  }

  /**
   * display inventory category tree 
   */ 
  function recurseInventoryCategory ($o) {
    echo "<li><a href='store/{$o['id']}/'>{$o['title']}</a><ul class='list_indent'>";
    foreach ($o['children'] as $v) {
      recurseInventoryCategory($v);
    }
    echo "</ul></li>";
  }