Iterating through a multi dimensional array with PHP's RecursiveIteratorIterator

Question

I have to cache a tree structure and access it later on. Problem: I really can't figure out how to declare the data so that it fits to RecursiveIteratorIterator etc. It's probably a very n00bish question, but I have tried lots of combinations and ran out of ideas :-(

Conceptually the data looks like this:

ROOT code : 1111, label : Universe
   - code : 2000, label : Asia
      - code : 3203, label : Hongkong
           -code : 2081, label: Greater Area
           -code : 2041, label: Downtown
      - code : 4020, label : Shanghai
   - code : 6201, label : Africa
   - code : 321, label : North America

I want to access all direct childs to a given code, e.g. for Asia Hongkong and Shanghai. RecursiveIteratorIterator seems to make this easy.

// looking for Asia with code = 2000
$iterator = new RecursiveIteratorIterator(new Universe_Tree($tree));
foreach ($iterator as $key => $item) {
       if ($item->code == 2000) {
            var_dump($iterator->callGetChildren());

       }
}

Class Universe_Tree does not do much yet:

class Universe_Tree extends ArrayIterator implements RecursiveIterator  {

    public function hasChildren() {
        return (is_array($this->current()));
    }

    public function getChildren() {
        return new self($this->current());
    }

}

My best approach was to create objects of each node and store them in a nested array

$universe = new stdClass();
$universe ->code = 1111;
$universe ->label = "Universe"; 

$tree = array(
  array($universe,
    array(
       $asia,
      (array($shanghai,$hongkong)),
       $europe
        // and so on
       )
      );

Unfortunately $iterator->callGetChildren() does not return the children, just the current element. Probably because the nodes are not nested together correctly. I also tried to nest arrays with a parentId but this lead to an error message from ArrayIterator that this is not an array or object, though according to var_dump it was an array. What else could I try?

Answer 1

This is a kind of answer. Actually I gave up and went to a solution based on SimpleXML. Really simple and very few code. Eventually somebody will come across this question and my "solution" might be a way for him, too. So I'll include it here:

// data represented as xml
$xmlstring = <<<XML
<orgtree>
  <level number="1">
        <unit label="Universe" code="1111">
            <level number="2">
                <unit label="Asia" code="2000"></unit>
                    <level number="3">
                        <unit label="Hongkong" code="3203"></unit>
                           <level number="4">
                               <unit label="Greater Area" code="2081"></unit>
                               <unit label="Downtown" code="2041"></unit>
                           </level>
                    </level>
                </unit>
            <unit label="Africa" code="6201"></unit>
            <unit label="North America" code="321"></unit>
            </level>
        </unit>
    </level>
</orgtree>
XML;


   $xml = simplexml_load_string($xmlstring);
   // use xpath to select part of xml
   foreach ($xml->xpath('//unit[@code="2000"]') as $parentUnit)
   {
        $subtree = $parentUnit->level;
        foreach ($subtree->unit as $unit) {
                 var_dump($unit["label"]);
        }
   }