Validate dates then transfer it to iso string react

My problem is that I need to validate my date using any validation library (joi, yup, superstruct..etc) and after that, I need to cast the date object to iso string

I use Flatpikr , react-hook-form , joi OR yup

This my approach at first glance

1. Flatpickr >> Date >> Validate >> toISOString() if validation succeed

I tried to achieve the first approach via yup but no hope

I tried to make a pre and post transform in yup

I opened a question in their repository explaining my steps

https://github.com/jquense/yup/issues/1153

My approach in joi didn't succeed also

i used this code

joi
  .date()
  .iso()
  .required()
  .min(new Date())
  .messages({
    'any.required': `Required.`,
    'date.format': `Required`,
    'date.base': `Should be a type of number`,
    'date.min': `The date should be in future`,
  });

and i have used

{ convert : false }

in joi options to prevent joi from converting the values

when setting convert to false, all of my validation schemas succeed even if my variables was required or empty