public function serialize() {
		$properties = $this->getSerializeVars();
		
		$data = array();
		
		foreach ($properties as $p) {
			$data[$p] = $this->$p;
		}
		
		return json_encode($data);
	}
public function serialize() {
		$properties = $this->getSerializeVars();
		
		$data = array();
		
		foreach ($properties as $p) {
			$data[$p] = $this->$p;
		}
		
		return json_encode($data);
	}
Returns serialized string
We presume there will not be some complex objects
only integers/strings etc

@return string JSON string with values of selected properties