public function getOrderBy($field)
    {
        return array_key_exists($field, $this->orderBy) ?
                  $this->orderBy[$field]
                : null;
    }
public function getOrderBy($field)
    {
        return array_key_exists($field, $this->orderBy) ?
                  $this->orderBy[$field]
                : null;
    }
public function getOrderBy ( $ field ) { return array_key_exists ( $ field , $ this -> orderBy ) ? $ this -> orderBy [ $ field ] : null ; }
Returns the OrderBy direction for the field specified

@param string $field the field name to lookup

@return string Returns the direction (ASC or DESC) for the field specified, or null if it doesn't exist.
Returns the OrderBy direction for the field specified