Asp.Net Mvc Sample code

[Benoit R.]

Hi,

I have not found sample on for Asp.Net Mcv, i give you mine. 

With only the  "HelperReCaptcha.cs" File in your project, you will be able to use this awsome Captcha in 2 line of code :)

 

HelperReCaptcha.cs

using System;
using System.Collections.Generic;
using System.Linq;
using System.Net.Http;
using System.Net.Http.Headers;
using System.Text;
using System.Threading.Tasks;
using System.Web;
using System.Web.Mvc;
 
namespace System.Web.Mvc.Html
{
    public static class ReCaptcha
    {
        //https://developers.google.com/recaptcha/docs/verify
 
        public static MvcHtmlString ReCaptcha(this HtmlHelper helper, ReCaptchaModel.Theme theme = ReCaptchaModel.Theme.light)
        {
            var themeStr = theme != ReCaptchaModel.Theme.light ? " data-theme='" + theme.ToString() + "' " : "";
            var sb = new StringBuilder();
            sb.Append(helper.ValidationMessage("Captcha").ToString());
            sb.Append("<script src='https://www.google.com/recaptcha/api.js' async defer></script>");
            sb.Append("<div class='g-recaptcha'" + themeStr + " data-sitekey='" + Config.reCAPTCHA.SiteKey + "'></div>");
            sb.Append("<noscript>");
            sb.Append("<div style='width: 302px; height: 352px;'>");
            sb.Append("<div style='width: 302px; height: 352px; position: relative;'>");
            sb.Append("<div style='width: 302px; height: 352px; position: absolute;'>");
            sb.Append("<iframe src='" + "https://www.google.com/recaptcha/api/fallback?k=" + Statics.reCAPTCHA.SiteKey + "'");
            sb.Append("frameborder='0' scrolling='no'");
            sb.Append("style='width: 302px; height:352px; border-style: none;'>");
            sb.Append("</iframe>");
            sb.Append("</div>");
            sb.Append("<div style='width: 250px; height: 80px; position: absolute; border-style: none;");
            sb.Append("bottom: 21px; left: 25px; margin: 0px; padding: 0px; right: 25px;'>");
            sb.Append("<textarea id='g-recaptcha-response' name='g-recaptcha-response'");
            sb.Append("class='g-recaptcha-response'");
            sb.Append("style='width: 250px; height: 80px; border: 1px solid #c1c1c1;");
            sb.Append("margin: 0px; padding: 0px; resize: none;' value=''>");
            sb.Append("</textarea>");
            sb.Append("</div>");
            sb.Append("</div>");
            sb.Append("</div>");
            sb.Append("</noscript>");
            return sb.ToMvcHtmlString();
        }
    }
}
namespace System.Web.Mvc
{
    public class ReCaptchaModel
    {
        public bool success { get; set; }
        public enum Theme
        {
            light,
            dark 
        }
    }
    public static class ReCaptchaValidate
    {
        public static async Task<bool> ValidateReCaptcha(this Controller controller, bool autoAddModelStateError = true)
        {
            var recaptchaResponse = controller.Request.Form["g-recaptcha-response"];
            bool succses = false;
            if (!recaptchaResponse.IsNullOfEmpty())
                using (var client = new HttpClient())
                {
                    client.BaseAddress = new Uri("https://www.google.com/recaptcha/");
                    client.DefaultRequestHeaders.Accept.Clear();
                    client.DefaultRequestHeaders.Accept.Add(new MediaTypeWithQualityHeaderValue("application/json"));
 
                    // New code:
                    HttpResponseMessage response = await client.GetAsync("api/siteverify?secret=" + Config.reCAPTCHA.SecretKey + "&response=" + recaptchaResponse);
                    if (response.IsSuccessStatusCode)
                    {
                        ReCaptchaModel CaptchResponse = await response.Content.ReadAsAsync<ReCaptchaModel>();
                        succses = CaptchResponse.success;
                    }
                    else
                        succses = false;
                }
            if (!succses && autoAddModelStateError)
                controller.ModelState.AddModelError("Captcha", LangRess.PleaseProveYouAreHumain);
            return succses;
        }
    }
}

to aply it on the view:

just use @Html.ReCaptcha()

@using (Html.BeginForm())
{ 
    @Html.AntiForgeryToken()
    <input type="email" name="Email" /> 
    
    @Html.ReCaptcha()
    
    <button type="submit">Send!</button>
}

then validate in the controller, with or without ModelState Error:

        [HttpPost, ValidateAntiForgeryToken]
        public async Task<ActionResult> Captcha(string email)
        {
            //1)With ModelState
            var valide = await ((Controller)this).ValidateReCaptcha();
            if (ModelState.IsValid)
                return View("Succses"); //a human is confirmed!
            return View(); //Fail, return the view to display modelstate error
 
            //2)Without ModelState
            var isValide = await ((Controller)this).ValidateReCaptcha(autoAddModelStateError: false);
            if (isValide)
                { /*succses*/ }
            else
                { /*fail*/}
        }

[Tahir Khalid]

Thanks Benoit, exactly what I was looking for.  Just one question, is this for the "new" Google ReCaptcha?

Thanks,

T

[Tahir Khalid]

Hey worked great, still not sure how the new one works but it does haha

[tuzemec]

Either I'm doing something wrong or you are hiding the captcha when it fails to validate (or the user just leave it untouched).

And I'm not sure that this is a good behaviour.

...

[Tahir Khalid]

use the following client side code to reset the control (or put it into the extension where the HTML is built):

grecaptcha.reset();

tuzemec if you look in the main group I have posted a guide on how to implement the google reCAPTCHA in an MVC 4 project (adapting Benoit's code).

Cheers,

T

[tuzemec]

Yeah, sorry - it's my bad.

I just found out why it's hidden for me when the model invalidates and I was about to delete my post :-)

Thanks for the quick reply :-)