abstract class DataObject
{
  protected $data = array();
 
  public function __construct( $data )
  {
    foreach ( $data as $key => $value ) {
        if ( array_key_exists( $key, $this->data ) )
          $this->data[$key] = $value;
    }
  }
 
  public function getValue( $field )
  {
    if ( array_key_exists( $field, $this->data ) )
      return $this->data[$field];
    else
      exit( "Field not found" );
  }
 
  public function getValueEncoded( $field )
  {
    return htmlspecialchars( $this->getValue( $field ) );
  }
 
  protected function connect()
  {
    try {
      $conn = new PDO( DB_DSN, DB_USERNAME, DB_PWD );
      $conn->setAttribute( PDO::ATTR_PERSISTENT, TRUE );
      $conn->setAttribute( PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION );
    }
    catch ( PDOException $e) {
      exit( 'Connection failed: '. $e->getMessage() );
    }
 
    return $conn;
  }
 
  protected function disconnect( $conn )
  {
    $conn = NULL;
  }
}