[PHP] Re: Getting data from table as a tree

[Brian Kell]

Well, first off, a little bit of formatting (line numbers added for  
clarity):

 1 $tpl->assign("tree",
 2     array(
 3         "element" => array(
 4             array(
 5                 "name" => "test1",
 6                 "element" => array(
 7                     array(
 8                         "name" => "test1.1"
 9                     ),
10                     array(
11                         "name" => "test1.2",
12                         "element" => array(
13                             array(
14                                 "name" => "test1.2.1"
15                             ),
16                             array(
17                                 "name"  => "test1.2.2"
18                             )
19                         )
20                     )
21                 )
22             )
23         )
24     )
25 );
It appears that each node is represented as an array. This array contains  
a "name" and, if the node has any children, another array called "element"  
that contains the child nodes. In addition, the root node is an element of  
some "superroot", which is the array starting on line 2. (So if you want  
to have multiple trees, you can; just define multiple nodes with a pid of  
0.)

I think the following functions should do approximately what you want. I'm  
assuming MySQL here, since that's what I'm used to. If you're not using  
MySQL, you should be able to adapt this to your database easily enough.

function build_tree() {
    $subtree = build_subtree(0);
    if ($subtree !== NULL)
        return array("element => $subtree);
    else
        return NULL;
}
function build_subtree($pid) {
    $result = mysql_query("SELECT id, name FROM tbl WHERE pid='$pid'");
    if (!$result)
        die("Can't query for pid $pid: ".mysql_error());
    if (mysql_num_rows($result)) {
        $subtree = array();
        while ($row = mysql_fetch_assoc($result)) {
            $node = array();
            $node['name'] = $row['name'];
            $element = build_subtree($row['id']);
            if ($element !== NULL)
                $node['element'] = $element;
            array_push($subtree, $node);
        }
        return $subtree;
    } else
        return NULL;
}
Be careful with this, because I didn't actually test this at all. Run it  
on a few test cases and make sure it gives you what you want.

Brian
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