public function __construct($destinationField, $fromTable, $relation, $alias, $type, $on, $fetch)
{
$this->relation = $relation;
$this->alias = $alias;
$this->destinationField = $destinationField;
$this->fromTable = $fromTable;
$this->type = $type;
$this->on = $on;
$this->fetch = $fetch;
}