// Use koa-validate

'use strict';
var koa = require('koa');
var app = koa();
var router = require('koa-router')();
require('koa-validate')(app);
 
app.use(require('koa-body')({multipart:true , formidable:{keepExtensions:true}}));
app.use(router.routes()).use(router.allowedMethods());
router.post('/signup', function * () {
    //optional() means this param may not in the params.
    this.checkBody('name').optional().len(2, 20,"are you kidding me?");
    this.checkBody('email').isEmail("your enter a bad email.");
    this.checkBody('password').notEmpty().len(3, 20).md5();
    //empty() mean this param can be a empty string.
    this.checkBody('nick').optional().empty().len(3, 20);
    //also we can get the sanitized value 
    var age = this.checkBody('age').toInt().value;
    yield this.checkFile('icon').notEmpty().size(0,300*1024,'file too large').move("/static/icon/" , function*(file,context){
        //resize image
    });
    if (this.errors) {
        this.body = this.errors;
        return;
    }
});