How to validate alternatives in Yup?

Question

I'm used to Joi validation syntax, but right now trying to migrate some code to Yup syntax.

In Joi, I used to do this:

  field: Joi.alternatives().try(
    Joi.number(),
    Joi.string(),
  )

This makes the field either a number or a string.

How to achieve that using Yup?

Answer 1

UPDATE:

I created a better solution, which works for any number of whatever schema types you pass!

First you define a method called oneOfSchemas

yup.addMethod(yup.MixedSchema, "oneOfSchemas", function (schemas) {
  return this.test(
    "one-of-schemas",
    "Not all items in ${path} match one of the allowed schemas",
    (item) =>
      schemas.some((schema) => schema.isValidSync(item, { strict: true }))
  );
});

Then you use it as follows:

title: yup
  .mixed()
  .oneOfSchemas([
    yup
      .object()
      .noUnknown()
      .shape(SchemaObject1),
    yup
      .object()
      .noUnknown()
      .shape(SchemaObject2),
  ]),

Inspired by https://gist.github.com/cb109/8eda798a4179dc21e46922a5fbb98be6

This is the only way I found, please correct me if I'm wrong or if you have better answers:

field: yup.lazy((val) => (isNaN(val) ? yup.string() : yup.number()))

This however won't work when the alternatives are objects, which I would like to find a solution for.