const Koa = require('koa');
const parameter = require('koa-parameter');

const app = new Koa();

parameter(app); // add verifyParams method, but don't add middleware to catch the error
// app.use(parameter(app)); // also add a middleware to catch the error.

app.use(async function (ctx) {
  ctx.verifyParams({
    name: 'string'
  });
});

const Koa = require('koa');
const parameter = require('koa-parameter');

const app = new Koa();

parameter(app, function() {
  // Same example with node-parameter
  var args = Array.prototype.slice.call(arguments);
  // Assume there have I18n.t method for convert language.
  return I18n.t.apply(I18n, args);
});

app.use(async function (ctx) {
  ctx.verifyParams({
    name: 'string'
  });
});