PHP Class for Accessing Data from Google Docs Spreadsheet

spreadsheet.php

<?php

Class DocDB {
	private $key;
	private $url;
	private $file;
	private $json;
	private $rows;
	private $data = array();
	private $columns = array();
	private $db_row = array();

	public function __construct($key, $columns = array()){
		$this->key = $key;
		$this->url = 'http://spreadsheets.google.com/feeds/list/' . $this->key . '/od6/public/values?alt=json';

		$this->file = file_get_contents($this->url);
		$this->json = json_decode($this->file);
		$this->rows = $this->json->{'feed'}->{'entry'};
		$this->columns = $columns;
		$this->collect();
	}

	public function toArray(){
		return $this->data;
	}

	public function toJSON(){
		return json_encode($this->data);
	}

	private function collect(){
		foreach($this->rows as $row) {
			foreach ($this->columns as $key) {
				$this->db_row[$key] = $row->{'gsx$'.$key}->{'$t'} ;
			}

			array_push($this->data, $this->db_row);
		}
	}
}