Nested sets, php array and transformation

Question

I need to transform my nested sets structure (mysql) into json for this spacetree 1) http://blog.thejit.org/wp-content/jit-1.0a/examples/spacetree.html

I found this function to create an array from nested sets: 2) http://semlabs.co.uk/journal/converting-nested-set-model-data-in-to-multi-dimensional-arrays-in-php

I can also convert php array into json with PHP function json_encode

My problem: the function nestify (from second link) gives me not exactly that i need. I need something like this: http://pastebin.com/m68752352

Can you help me change the function "nestify" so it gives me the correct array?

Here is this function one more time:

function nestify( $arrs, $depth_key = 'depth' )
    {
        $nested = array();
        $depths = array();

        foreach( $arrs as $key => $arr ) {
            if( $arr[$depth_key] == 0 ) {
                $nested[$key] = $arr;
                $depths[$arr[$depth_key] + 1] = $key;
            }
            else {
                $parent =& $nested;
                for( $i = 1; $i <= ( $arr[$depth_key] ); $i++ ) {
                    $parent =& $parent[$depths[$i]];
                }

                $parent[$key] = $arr;
                $depths[$arr[$depth_key] + 1] = $key;
            }
        }

        return $nested;
    }

wimvds · Accepted Answer · 2009-05-20 09:00:01Z

10

The following snippet should do the trick, adapted from some PHP Doctrine code I found on the web :

function toHierarchy($collection)
{
        // Trees mapped
        $trees = array();
        $l = 0;

        if (count($collection) > 0) {
                // Node Stack. Used to help building the hierarchy
                $stack = array();

                foreach ($collection as $node) {
                        $item = $node;
                        $item['children'] = array();

                        // Number of stack items
                        $l = count($stack);

                        // Check if we're dealing with different levels
                        while($l > 0 && $stack[$l - 1]['depth'] >= $item['depth']) {
                                array_pop($stack);
                                $l--;
                        }

                        // Stack is empty (we are inspecting the root)
                        if ($l == 0) {
                                // Assigning the root node
                                $i = count($trees);
                                $trees[$i] = $item;
                                $stack[] = & $trees[$i];
                        } else {
                                // Add node to parent
                                $i = count($stack[$l - 1]['children']);
                                $stack[$l - 1]['children'][$i] = $item;
                                $stack[] = & $stack[$l - 1]['children'][$i];
                        }
                }
        }

        return $trees;
}

answered May 20, 2009 at 9:00

wimvds

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3 Comments

Laurens Kling Over a year ago

Can anybody tell me what the & does in for example $stack[] = & $trees[$i];

wimvds Over a year ago

It stores the reference of the tree item into the stack (which is just a pointer to the current object instead of a copy of it). For more info you could read the References Explained chapter in the PHP manual.

userlond Over a year ago

Important thing. To use this function you need to apply ordering items of collection by left_id (it's service field of nested sets structure) column!

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