yup.ref(...).transform is not a function

[iamvanja]

Trying to create a computed field that depends on another one. Something like:

...
  originalField: yup.array().default([]),
  computedField: yup.ref('originalField')
    .transform(function (currentValue, originalValue) {
      let value = currentValue || originalValue

      // do some transformation here

      return value
    }),
...

Is .ref not designed for something like this? If not, is there anything else I could try?
I would like to keep this logic on a schema level if possible.

Thanks!

[jquense]

yes that's right, a Ref isn't a schema, its only proxy value. In not sure exactly want you want to do but you can resolve a ref value in a transform:

yup.array().transform(function () {
  const otherValue = this.resolve('otherField')
})

[iamvanja]

That's perfect! Thanks :)

[iamvanja]

It looks like computedField will run transform only when computedField's value is provided. Otherwise it will return what is defined through default. Which makes sense, but does not work quite work with my idea of an "imaginary field".
Thanks for the lightning fast response nonetheless :)

[iamvanja]

This can be closed.

[vonagam]

For future readers. Right now reference documentation is wrong and second argument for ref is actually not an options object, but mapFn which maps value from referenced to resolved one. Example:

yup.object({
  x: yup.ref('y', (a) => a + 1),
}).cast({
  y: 3,
}); // => {y: 3, x: 4}

[jquense]

I HAVE NO IDEA WHEN I ADDED THAT AND DON'T REMEMBER WHY :P

[vonagam]

Well, you might have the same need as the opener of this issue.

A valid need.

Unlike contextPrefix option, which is not used by anyone (since nobody asked why it isn't working) and complicates things a bit, since you will not be able to simply use reference.key as unique id (like here), because $ref and @ref might point to the same object if second one uses @ as contextPrefix, but will have different keys (so blacklist/whitelist might not work properly).

[jquense]

Yeah there a few crufty things originally added I think to match joi, but they aren't used and we aren't really trying to match joi anymore. I'm glad for the second pair of eyes on the old code 👍