django_recaptcha.py

import urllib
import json


class Recaptcha():
    url = 'https://www.google.com/recaptcha/api/siteverify'
    # Get secret an public key from https://www.google.com/recaptcha/admin/
    secret = 'YOUR_SECRET_KEY'
    site_key = 'YOUR_SITE_KEY'

    def __init__(self, DEBUG=False):
        if DEBUG:
            self.secret = 'YOUR_LOCAL_SECRET_KEY'
            self.site_key = 'YOUR_LOCAL_SITE_KEY'

    def get_results(self, recaptcha_response: str) -> dict:
        data = {
            'secret': self.secret,
            'response': recaptcha_response,
        }
        data = urllib.parse.urlencode(data).encode()
        req = urllib.request.Request(self.url, data=data)
        response = urllib.request.urlopen(req)
        return json.loads(response.read().decode())

Frontend setting in Django.

Add this code on the page template.

Insert this element in

     <input type="hidden" name="recaptcha_response" id="recaptchaResponse">

Add this code in header or footer.

    <script src="https://www.google.com/recaptcha/api.js?render={{ public_key }}"></script>
    <script>
        $(document).ready(function () {
            grecaptcha.ready(function () {
                grecaptcha.execute(`{{ public_key }}`, {action: 'submit'}).then(function (token) {
                    document.getElementById('recaptchaResponse').value = token;
                });
            });
        });
    </script>

Backend setting in Django

1. Make Recaptcha instance in the View class.
2. Set publick on context in get_context_data().
3. Get results by recaptca.get_results in form_valid().

class SignupView(CreateView):
    model = User
    form_class = UserForm
    template_name = "base/signup.html"
    success_url = reverse_lazy('base:signup_done')
    recaptcha = Recaptcha(DEBUG)

    def get_context_data(self, **kwargs):
        context = super().get_context_data(**kwargs)
        context['site_key'] = self.recaptcha.site_key
        return context

    def form_valid(self, form):
        recaptcha_results = self.recaptcha.get_results(self.request)
        if recaptcha_results.get('success') != True:
            return HttpResponse('Google Captcha error',status=500)