Model problem

[eluser]theprodigy[/eluser]

foreach ($res->result() as $r) {
// push found result onto existing tree
$tree[$r->id] = $r;
// create placeholder for children
$tree[$r->id]['children'] = array();
// find any children of currently found child
$tree = $this->generateTree($r->id, $tree[$r->id]['children']);
}

I think the problem lies in:

Code:

// push found result onto existing tree
$tree[$r->id] = $r;
// create placeholder for children
$tree[$r->id]['children'] = array();

$r is an object. So

Code:

$tree[24] = stdObject()
$tree[25] = stdObject()
etc

Then you turn around and try to add another dimension onto the array with the next line

Code:

$tree[$r->id]['children'] = array();

You were getting a different error when you were using result_array(), then you are now with result().

Try changing back to result_array()
Change your if to

Code:

if ($res->num_rows() > 0) {...}

and remove the '$tree =' from

Code:

$tree = $this->generateTree($r->id, $tree[$r->id]['children']);

It's also bad form to have an optional parameter in front of a required parameter in a function declaration

Code:

function generateTree( $parentid = 0, &$tree ){...}

should be

Code:

function generateTree( &$tree, $parentid = 0 ){...}