{
  body: schema; // validates request body
  headers: schema; // validates request headers
  params: schema; // validates path params
  query: schema; // validates query params
}

import { createErrorMiddleware } from "koa-yup-validator";
app.use(createErrorMiddleware());
//...your routes

import * as yup from "yup";
import validator from "koa-yup-validator";

const Pizza = yup.object().shape({
  name: yup.string().required(),
  toppings: yup.array().of(yup.string()),
});
const RequiredHeaders = yup.object().shape({
  Authorization: yup.string().required(),
  "x-pizza-maker": yup.string(),
});

router.post(
  "/pizza",
  validator({ body: Pizza, headers: RequiredHeaders }),
  (ctx) => {
    console.log(ctx.request.headers["x-pizza-maker"]);
    ctx.response.status = 200;
    ctx.response.body = "Valid pizza!";
  }
);

// Pass yup options for body
router.post(
  "/strict-pizza",
  validator(
    { body: Pizza, headers: RequiredHeaders },
    { body: { yup: { strict: true } } }
  ),
  (ctx) => {
    console.log(ctx.request.headers["x-pizza-maker"]);
    ctx.response.status = 200;
    ctx.response.body = "Valid pizza!";
  }
);