Rails: Validating min and max length of a string but allowing it to be blank

Question

I have a field that I would like to validate. I want the field to be able to be left blank, but if a user is entering data I want it to be in a certain format. Currently I am us

Answer 1

validates_length_of :reason, minimum: 3, maximum: 30

rspec for the same is

it { should validate_length_of(:reason).is_at_least(3).is_at_most(30) }