How to Create a Tree Menu in PHP/MySQL Without Recursion?

PHP / MySQL Build Tree Menu without Recursion

Background:

Building a tree menu from database data can be a common task. This article explores how to construct an unordered list (UL) menu tree from a PHP array of page objects without using recursion.

Data Setup:

Your page objects have the following attributes:

• id
• title
• parent_id (set to null for root pages)

Function Overview:

We'll create a function that takes an array of page objects and generates the corresponding HTML UL tree.

Helper Function: has_children()

This function checks if a page has child pages.

<code class="php">function has_children($rows, $id) {
  foreach ($rows as $row) {
    if ($row['parent_id'] == $id)
      return true;
  }
  return false;
}</code>

Recursive Build_Menu() Function

The build_menu() function iterates through the array and generates the HTML UL tree. It uses a variable $parent to keep track of the current parent page.

<code class="php">function build_menu($rows, $parent=0)
{  
  $result = "<ul>";
  foreach ($rows as $row)
  {
    if ($row['parent_id'] == $parent){
      $result.= "<li>{$row['title']}";
      if (has_children($rows,$row['id']))
        $result.= build_menu($rows,$row['id']);
      $result.= "</li>";
    }
  }
  $result.= "</ul>";

  return $result;
}</code>

Output:

After passing the array of page objects to the build_menu() function, you can echo the resulting HTML UL tree. The output will be a nested UL menu structure representing your database data.

<code class="php">echo build_menu($menu);</code>

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