Empty hidden fields

I have two columns in my table

hours

hours

and

semesters

semesters

. both are nullable.

in my form, I have a checkbox, it's value decides whether to show the hours or the semesters input using the

->hidden

->hidden

method

now I don't want both semesters and hours to be set at the same time, so for example if

horus

horus

is shown I want to make sure

semesters

semesters

is null when saving the form and vice-verca