How to validate not required CPF field

[Xavoski]

Hello.
Thanks for your work.

I am in trouble with this gem, it validates the CPF properly. But the problem is that my CPF field is not required.
When i try to submit my form, i receive the message that CPF is invalid, but actually it is null and that is ok.

Could you help me with that?

Thanks.

[wbotelhos]

@Xavoski you can use validates :cpf, allow_nil: true, cpf: true to allow nil.