yup js setidaknya satu bidang diperlukan
var schema = yup.object().shape({
a: yup.string().when(['b', 'c'], {
is: (b, c) => !b && !c,
then: yup.string().required()
}),
b: yup.string().when(['a', 'c'], {
is: (a, c) => !a && !c,
then: yup.string().required()
}),
c: yup.string().when(['a', 'b'], {
is: (a, b) => !a && !b,
then: yup.string().required()
})
}, [['a', 'b'], ['a', 'c'], ['b','c']]) // <-- HERE!!!!!!!!
Rodrigo Barbosa Anselmo