Conditional validation

@jaredpalmer : Thanks for this great library. It’s much better than redux-form.

Btw, I have one question for the following form:

Each state has a name and a bool field named no_cost. If no_cost = true, there’s no incurring cost.

I know Yup support conditional validation, but would you pls tell me how to apply it with formik?

[rostero1]

Untested:

validationSchema: Yup.object().shape({
  name: Yup.string().required(),
  no_cost: Yup.boolean(),
  cost: Yup.number().when('no_cost', {
    is: true,
    then: Yup.number()
      .required('cost is required'),
    otherwise: Yup.number(),
  })
})

[jaredpalmer]

@DavidCasillasRivero to avoid an arrow function debate 😄