This is a sample rules object that shows the interaction between country and phone number fields in a state object.

CountryAndPhoneNumberRules.js

const rules = {
  country: [
    {
      name: 'phoneNumber',
      path: ['fields', 'phoneNumber'],
      props: (countryNewValue, state) => ({
        editable: countryNewValue && countryNewValue !== '',
        countryPhoneCode: countryPhoneCodeMapper[countryNewValue]
      })
    }
  ]
}