PHP RecursiveIterator traversing - php

Question

I have a structure representing a form and I want to iterate it using RecursiveIterator.
The problem is this only returns the top-level questions. What am I doing wrong?
Whole form:
class Form implements RecursiveIterator{
private $id;
private $caption;
private $other_text;
private $questions = array();
private $current;
private function __construct(DibiRow $row){
$this->id = $row->id;
$this->caption = $row->caption;
$this->other_text = $row->other_text;
$this->loadQuestions();
}
private function loadQuestions(){
$questions = dibi::query('SELECT * FROM cyp_questions WHERE form_id = %i AND parent_id IS NULL', $this->id);
while($question = $questions->fetch()) $this->questions[] = new Question($question->question_id, $question->type, $question->caption, $question->other_text, $question->triggers_unique == 1);
}
/**
* #throws InvalidArgumentException
* #param $id
* #return Form
*/
public static function loadById($id){
$form = dibi::query('SELECT * FROM cyp_forms WHERE id = %i', $id)->fetch();
if($form === false) throw new InvalidArgumentException('Form with id '.$id.' was not found.');
return new Form($form);
}
/**
* #throws FormFieldException
* #return bool
*/
public function validate($postfields){
}
public function getQuestions(){
return $this->questions;
}
public function getChildren(){
return $this->questions[$this->current];
}
public function hasChildren(){
return count($this->questions) > 0;
}
public function current(){
return $this->questions[$this->current];
}
public function key(){
return $this->current;
}
public function next(){
$this->current++;
}
public function rewind(){
$this->current = 0;
}
public function valid(){
return isset($this->questions[$this->current]);
}
}
Question:
class Question implements RecursiveIterator{
private $id;
private $type;
private $answers = array();
private $subquestions = array();
private $other_text;
private $triggers_unique;
private $caption;
private $current = 0;
public function __construct($id, $type, $caption, $other_text = null, $triggers_unique = false){
$this->id = $id;
$this->type = $type;
$this->caption = $caption;
$this->other_text = $other_text;
$this->triggers_unique = $triggers_unique;
$this->setSubQuestions();
}
private function setSubQuestions(){
$questions = dibi::query('SELECT * FROM cyp_questions WHERE parent_id = %i', $this->id);
while($question = $questions->fetch()) $this->subquestions[] = new Question($question->question_id, $question->type, $question->caption, $question->other_text, $question->triggers_unique == 1);
}
public function getOtherText(){
return $this->other_text;
}
public function getCaption(){
return $this->caption;
}
public function addAnswer($answer){
$this->answers[] = $answer;
}
public function getChildren(){
return $this->subquestions[$this->current];
}
public function hasChildren(){
return count($this->subquestions) > 0;
}
public function current(){
return $this->subquestions[$this->current];
}
public function key(){
return $this->id;
}
public function next(){
++$this->current;
}
public function rewind(){
$this->current = 0;
}
public function valid(){
return isset($this->subquestions[$this->current]);
}
public function getAnswers(){
return $this->answers;
}
}
Iteration:
$form = Form::loadById(1);
foreach($form as $question){
echo $question->getCaption().'<br />';
}

Answer 1

To iterate over a RecursiveIterator, you have to wrap it into a RecursiveIteratorIterator.
See some examples at
Introduction to Spl
SplWiki
The default iteration mode is only to list leaves. If you also want the containing nodes to appear in the iteration, pass RecursiveIteratorIterator::SELF_FIRST as the second argument to the constructor of the RecursiveIteratorIterator

Answer 2

Well, as you can see here
public RecursiveIterator RecursiveIterator::getChildren ( void )
Returns an iterator for the current iterator entry.
the method should return an object implementing the iterator. Your method return a simple array.
My guess would be to return something like:
public function getChildren(){
return new Question($this->subquestions);
}
This is because you're using a RECURSIVE iterator so it's expected to have each node of the tree of the same type (an iterator)