Yup validation based on other data

schema.ts

import * as Yup from 'yup';
import type { MyType } from 'my-types-package';
import { MyOtherSchema } from 'kotk-vdb';

export const MySchema = (
  otherData: MyType,
  otherValidatorFn: (value: string, dataId: string) => Promise<boolean>
) => {
  return {
    simpleSelect: Yup.string()
      .required('Select a valid value')
      .oneOf(['a', 'b', 'c']),
    externalValidator: Yup.string()
      .when('otherField', {
        is: 'otherFieldValue',
        then: (schema) => schema
          .min(3, 'Minimum 3 characters')
          .max(100, 'Max 100 characters')
          .required('The field is required')
          .test('otherValidatorFn', 'Invalid value.', async (value) => {
            return await otherValidatorFn(value, otherData.id)
          }),
        }),
    ...MyOtherSchema,
    otherDataBasedValue: Yup.boolean()
      .when('otherValue', {
        is: (value) => value != otherData.otherValue,
        then: (schema) => schema.test('isFalse', 'Cannot be false', (value) => !value),
      }),
    otherFormData: Yup.string()
      // Because we rely on parent data in the form we use a test instead of
      // "when", because the other field may not be present in the data passed
      // to this schema.
      .test('isRequired', 'Error message', function (value, context) {
        if (context?.parent?.otherFormField !== undefined && context?.parent?.otherFormField !== 'value' ) {
          return value === '1' || value === '0';
        }
        return true;
      }),
    otherNestedFormData: Yup.string()
      // As above, but in this case the parent is also nested.
      .test('isRequired', 'Error message', function (value, context) {
        // If parent is also nested
        const rootCtx = context?.from?.[context?.from?.length - 1]?.value;
        return true;
      }),
  }
}