Best practice on indicating a model error to the controller in Laravel

Lets say I have my business logic in a Model, for example in Student.php (that extends Model).

In my controller, I get an instance of that model: $myStudent = Student::find(1);

Then I want to perform some action on it, say: $myStudent->graduate();

But my business logic says that because of some condition, this action can't be performed. How do I pass this information to the controller? Via a return value? Via an exception? Some other way?

1. Return value: If I return a value (say, 0:success, 1:Error because average is below 70, 2:Error because average is below 50), part of the business logic would leak into the controller, which should be avoided.

2. Exception: If the request is successful the normal execution of the code continues, but if not I throw an exception along with some text that is displayed to the user.

Is an exception the way to go? Any other way to do this? Thanks!

via Chebli Mohamed