如何创建没有父级ID的嵌套多级菜单

Question

I searched on many posts, but I can't find one to fix my problem.

In my database I have some data : a name and a "treepath" like "1.1.2". I don't have a parent ID or anything like that. So my question is : is there a way to createa nested multi level menu with only the "treepath" ?

In my table I got (ID | NAME | TREEPATH):

• 0 | Phone | 1
• 1 | Samsung | 1.1
• 2 | Galaxy S | 1.1.1
• 3 | Galaxy Note | 1.1.2

...

Output I need :

<ul>
  <li><a href="">1. Phones</a>
  <ul>
      <li><a href="">1.1. Samsung</a>
      <ul>
         <li><a href="">1.1.1. Galaxy S</a></li>
         <li><a href="">1.1.2. Galaxy Note</a></li>
         <li><a href="">1.1.3. Galaxy Ace</a></li>
       </ul></li>
        <li><a href="">1.2. Apple</a></li>
        <li><a href="">1.3. Google</a></li>
    </ul></li>
</ul>

I certainly need a recursive function with php, but i can't got it right, so if anyone could help me on this one, that'd be great !

Thanks !

Answer 1

Well, you could use a recursive function that employs regular expressions, but that might be sub-optimal. Pseudo-code follows:

function drawTree($root) {
  while($results = yourQuery("SELECT * FROM table WHERE treepath REGEXP '^{$root}\.'")) {
    echo "stuff";
    drawTree($results['treepath']);
  }  
}

Answer 2

Your situation is odd.

I don't see a technical reason not to just have a parent id in your table. Or to use first normal form. Feels a bit contrived, but you could do something like:

<?php
$db = new mysqli(...);
$stmnt = $db->prepare("select name, treepath, LENGTH(treepath) - LENGTH(REPLACE(treepath, '.', '')) AS depth from tree order by treepath");
$stmnt->bind_result($name,$treepath,depth);
$tree = array();
$current_depth = 0;
while($stmnt->fetch())
{
  if($current_depth < $depth)
  {
    echo '<ol><li>' . $name . '</li>';
    $current_depth=$depth;
  }
  else if($current_depth == $depth)
  {
    echo '<li>' . $name . '</li>';
  }
  else //current_depth greater than depth
  {
    echo '</ol><li>' . $name .'</li>';
  }
}
$stmnt->close();
$db->close();
echo '</ol>';
?>

Not tested, will need tweeks.

Answer 3

If your application needs to provide nested menus, you are better off implementing nesting ( In database language, it would be grouping, foreign keys and constraints ) in your database. It's not recommended that you maintain different designs in your presentation layer and database layer. After all, a strong database design is pivotal for any application, isn't it?

There are many other advantages as well - you streamline your application design, data remains organized and consistent, lesser effort in transforming database content into presentation content, and it becomes easier to add new features as well. Why don't you start with some categorization and a good schema design?

If you ask me, I would make something like a " phones " table that has phone_name, year, manufacturer, model, type etc. Again, there would be a different table called manufacturers which have manufacturer id's, names, years , and other information. You can also have another table for " type ". There will be foreign key relationships between manufacturer id's and manufacturer column in phone table and similar stuff with other columns/tables as well. If you are confused, a good place to start off would be drawing an ER diagram which will eventually be put down into tables and views.