main.go

package main

import (
	"fmt"

	"github.com/kataras/iris"

	"github.com/kataras/iris/middleware/recaptcha"
)

// keys should be obtained by https://www.google.com/recaptcha
const (
	recaptchaPublic = "6Lf3WywUAAAAAKNfAm5DP2J5ahqedtZdHTYaKkJ6"
	recaptchaSecret = "6Lf3WywUAAAAAJpArb8nW_LCL_PuPuokmEABFfgw"
)

func main() {
	app := iris.New()

	r := recaptcha.New(recaptchaSecret)

	app.Get("/comment", showRecaptchaForm)

	// pass the middleware before the main handler or use the `recaptcha.SiteVerify`.
	app.Post("/comment", r, postComment)

	app.Run(iris.Addr(":8080"))
}

var htmlForm = `<form action="/comment" method="POST">
	    <script src="https://www.google.com/recaptcha/api.js"></script>
		<div class="g-recaptcha" data-sitekey="%s"></div>
    	<input type="submit" name="button" value="Verify">
</form>`

func showRecaptchaForm(ctx iris.Context) {
	contents := fmt.Sprintf(htmlForm, recaptchaPublic)
	ctx.HTML(contents)
}

func postComment(ctx iris.Context) {
	// [...]
	ctx.JSON(iris.Map{"success": true})
}