yup_index_based_validation.ts

export const schemaThirdStepPoll = Yup.object().shape<Partial<PollOrOssParams>>({
  questions: Yup.array()
    .ensure()
    .of(
      // @ts-ignore
      Yup.lazy<any>((item, options) => {
        const itemIndex = options.parent.indexOf ? options.parent.indexOf(item) : -1;

        let description = Yup.string().min(50);
        if (itemIndex > 0) {
          description = description.required();
        }

        return Yup.object().shape({
          text: Yup.string().required().min(20),
          type: Yup.string().required(),
          description,
          answers: Yup.array()
            .ensure()
            .of(
              Yup.object().shape({
                answer: Yup.string().required(),
              })
            ),
        });
      })
    ),
});