Help me to types a requiredWhen function

[TeChn4K]

Hi,

First of all, I would like to thanks Fabian and the contributors of this awesome "Pipe rewrite" release! Valibot now meets all my needs, at the crossroads between what Zod and Yup do. Thanks!

---

I'm trying to reduce the amount of lines in my schemas with some helpers, but I'm having trouble with the typing.

I use a lot of forward and partialCheck in my schemas. So here is my current solution :

Before :

const schema = v.pipe(
  v.object({
    isMandatory: v.boolean(),
    randomField: v.nullable(v.string()),
  }),

  v.forward(
    v.partialCheck(
      [['isMandatory'], ['randomField']],
      (input) => !input.isMandatory || !!input.randomField,
      'field_missing',
    ),
    ['randomField'],
  ),
);

After

export const schema = v.pipe(
  v.object({
    isMandatory: v.boolean(),
    randomField: v.nullable(v.string()),
  }),

  requiredWhen(['randomField'], [['isMandatory']], (input) => input.isMandatory),
);

function requiredWhen<
  TInput extends Record<string, unknown>,
  TPathKeys extends v.PathKeys<TInput>,
  TPathList extends Array<TPathKeys>,
  TSelection extends v.DeepPickN<TInput, TPathList>,
>(pathKeys: TPathKeys, pathList: TPathList, requirement: (input: TSelection) => boolean) {
  return v.forward<TInput, v.BaseIssue<unknown>>(
    v.partialCheck<TInput, TPathList, TSelection, string>(
      // TODO: TS is complaining here...
      [...pathList, pathKeys],
      (input) => !!input[pathKeys[0]] || !requirement(input),
      'field_missing',
    ),
    pathKeys,
  );
}

Can you help me to correctly type this function? Maybe do you have any suggestion?
Thanks all

[fabian-hiller]

Yes, here is the fix:

function requiredWhen<
  TInput extends Record<string, unknown>,
  TPathKeys extends v.PathKeys<TInput>,
  TPathList extends Array<TPathKeys>,
  TSelection extends v.DeepPickN<TInput, TPathList>,
>(
  pathKeys: TPathKeys,
  pathList: TPathList,
  requirement: (input: TSelection) => boolean
) {
  return v.forward<TInput, v.BaseIssue<unknown>>(
    v.partialCheck<TInput, v.PathKeys<TInput>[], TSelection, 'field_missing'>(
      [...pathList, pathKeys],
      (input) => !!input[pathKeys[0]] || !requirement(input),
      'field_missing'
    ),
    pathKeys
  );
}

[TeChn4K]

That was fast! Thanks a lot

Last thing : TSelection does not seem to work well.

With this schema bellow, input type contains the whole schema, instead of randomField and isMandatory

export const schema = v.pipe(
  v.object({
    isMandatory: v.boolean(),
    randomField: v.nullable(v.string()),
    randomField2: v.nullable(v.string()),
    randomField3: v.nullable(v.string()),
  }),

  requiredWhen(['randomField'], [['isMandatory']], (input) => input.isMandatory),
);

[fabian-hiller]

This could work:

function requiredWhen<
  TInput extends Record<string, unknown>,
  const TPathKeys extends v.PathKeys<TInput>,
  const TPathList extends v.PathKeys<TInput>[],
  const TSelection extends v.DeepPickN<TInput, TPathList>,
>(
  pathKeys: TPathKeys,
  pathList: TPathList,
  requirement: (input: TSelection) => boolean
) {
  return v.forward<TInput, v.BaseIssue<unknown>>(
    v.partialCheck<TInput, v.PathKeys<TInput>[], TSelection, 'field_missing'>(
      [...pathList, pathKeys],
      (input) => !!input[pathKeys[0]] || !requirement(input),
      'field_missing'
    ),
    pathKeys
  );
}