PHP MySQL Multidimensional Array - Dropdown Menu - php

Question

I want to create my dropdown menu from a mysql query, but i'm having trouble with the sub-items.
My basic table:
NavigationID ParentID Name Url
1 1 Home home
2 2 About about
3 3 Products products
4 3 Category1 #
5 3 Category2 #
6 4 Product1 #
7 5 Product2 #
My simple MySQL Query and adding to array:
class Navigation{
private $data;
public function __construct($par){
if(is_array($par))
$this->data = $par;
}
public function __toString(){
return '<li>'.$this->data['Name'].'</li>';
}
}
$query = mysql_query("SELECT * FROM Navigation n") or die(mysql_error());
$num = mysql_num_rows($query);
$menuitems = array();
while($row = mysql_fetch_assoc($query)){
$menuitems[] = new Navigation($row);
}
echo '<div id="nav"><ul>';
foreach($menuitems as $item){
echo $item;
}
echo '</ul></div>';
The result of this is:
<div id="nav"><ul>
<li>Home</li>
<li>About</li>
<li>Products</li>
<li>Category1</li>
<li>Category2</li>
<li>Product1</li>
<li>Product2</li>
</ul></div>
But what I would REALLY like is this:
<div id="nav"><ul>
<li>Home</li>
<li>About</li>
<li>Products
<ul>
<li>Category1
<ul>
<li>Product1</li>
</ul>
</li>
<li>Category2
<ul>
<li>Product2</li>
</ul>
</li>
</ul>
</li>
</ul></div>
How can I achieve this result? I've tried many other examples, but none seems to help me. Maybe I'm not searching for the right thing.

Answer 1

Why to make it complicated, this could be done with a very simple recursive function.
This is what I did in my local machine. I have the connection parameter and then called a function
bulit_tree(0);
In this function it will check if the argument is 0 then select all
the item where id and parentid is same.
Then loop through and use the recursive function and generate sub tree.
Need to make sure that the $con is accesible within the function.
$con = mysql_connect("localhost","testuser","testpass");
$db_selected = mysql_select_db('testdb', $con);
if (!$db_selected) {
die ('Can\'t use testdb : ' . mysql_error());
}
bulit_tree(0);
function bulit_tree($pid=0){
global $con ;
if($pid == 0 ){
$qry = "select * from Navigation where NavigationID = ParentID";
$q = mysql_query($qry,$con);
if(mysql_num_rows($q) > 0 ){
echo '<ul>';
while($row = mysql_fetch_assoc($q)){
echo '<li>'.$row["Name"].'';
bulit_tree($row["NavigationID"]);
echo '</li>';
}
echo '</ul>';
}
}else{
$qry = "select * from Navigation where ParentID = ".$pid." AND NavigationID <> ".$pid;
$q = mysql_query($qry,$con);
if(mysql_num_rows($q) > 0 ){
echo '<ul>';
while($row = mysql_fetch_assoc($q)){
echo '<li>'.$row["Name"].'';
bulit_tree($row["NavigationID"]);
echo '</li>';
}
echo '</ul>';
}
}
}

Answer 2

You might need to restructure your DB first. Consider a join table. This comes handy especially if your Product falls into multiple categories.
Master table:
NavigationID Name Url
1 Home home
2 About about
3 Products products
4 Category1 #
5 Category2 #
6 Product1 #
7 Product2 #
Lookup Table:
NavigationID ParentId
1 1
2 2
3 3
4 3
5 3
6 4
7 5
Then in your class, you can make it structured like:
<?php
class Navigation{
private $menuitems;
public function __construct($par){
if(is_array($par))
$this->menuitems = $par;
}
public function __toString() {
$this->printNavigation($this->menuitems);
}
private function printMenuItem($menu) {
echo '<li>'.$menu->name.'';
if(count($menu->children)) {
print printNavigation($menu->children);
}
'</li>';
}
private function printNavigation($menuItems) {
echo "<ul>";
foreach ($menuitems as $menu {
$this->printMenuItem($menu);
}
echo "</ul>";
}
}
class MenuItem{
private $url;
private $name;
private $children;
public function __construct($par){
if(is_array($par)) {
$this->url = $par['url'];
$this->$name = $par['name'];
$this->children = $this->fetchChildren($par['NavigationID']);
}
}
function fetchChildren($id) {
$query = mysql_query("SELECT * from navigation n INNER JOIN Lookup l on l.parentID = n.NavigationID
WHERE n.NavigationID = $id") or die(mysql_error());
$num = mysql_num_rows($query);
if($num > 0) {
while($row = mysql_fetch_assoc($query)){
$this->children[] = new MenuItem($row);
}
}
}
}
$query = mysql_query("SELECT * from navigation n INNER JOIN Lookup l on l.NavigationID = n.NavigationID
WHERE l.NavigationID = l.parentIDn
AND l.NavigationID != n.NavigationID") or die(mysql_error());
$num = mysql_num_rows($query);
$menuitems = array();
while($row = mysql_fetch_assoc($query)){
$menuitems[] = new MenuItem($row);
}
$navigation = new Navigation($menuitems);
echo "<div id='nav'>$navigation</div>";

Answer 3

Thanx for all the comments. I've gone with Agha's suggestion of using a recursive function.
http://crisp.tweakblogs.net/blog/317/formatting-a-multi-level-menu-using-only-one-query.html