Lets say that I'm using
Parts from the documentation. I would like to be able to set an additional property in
RobotParts when I'm creating the relationship.
So when I automatically create the intermeddiate table with the following it would be possible to pass in a value to RobotParts to fill in a custom field.
// This only appears to be able to populate RobotParts with two keys and not another value. $robot->parts = $part;