Activate link upon reCAPTCHA success? - wordpress

Question

I'm working on a WordPress site. Basically, I publish download links (PDFs), and would like to stop web crawlers from accessing this content. This led me to Google's reCAPTCHA. Can I use this alone, so that when a user clicks/answers correctly, the links on the page will be made active? I'm having trouble editing a page in WordPress to do this. Thanks.
-Rudy.

Answer 1

I understand that you want to show link dynamically after the verification of the recaptcha.
You can create a an ajax that fetches the link after the verifcation of recaptcha passes.
To do this, we will use WordPress ajax requests, wp-ajax:
First, you register the ajax handler the request in the server side
add_action( 'wp_ajax_get_hidden_pdf_link', 'search_hidden_pdf_link' );
// add this line to handle requests of non logged in users
add_action( 'wp_ajax_nopriv_get_hidden_pdf_link', 'search_hidden_pdf_link' );
function search_hidden_pdf_link() {
// the response will be ajax response
header('Content-Type: application/json;charset=utf-8');
if(recaptcha_fails()){
// writing the failure response
echo json_encode(array('object' => 'error'));
wp_die();
}
$secret_pdf_link = generate_pdf_link();
// writing the succcess response
echo( json_encode( array('object' => 'success', 'link' => $secret_pdf_link)));
wp_die();
}
and in the front end, you create an ajax form, which asks and displays the link.
PDF Link
<form id="pdf-link-form" action="<?php echo admin_url('wp-ajax.php'); ?>">
<!-- some input that tells the backend which pdf to fetch -->
<input type="hidden" name="public_pdf_id" value="<?php echo $pdf_id; ?>">
<!-- the ajax request identifier, it is the suffix inside the action -->
<input type="hidden" name="action" value="get_hidden_pdf_link">
<div class="g-recaptcha" data-sitekey="your_site_key"></div>
</form>
<script>
$(document).ready(function () {
$('#pdf-link-form').submit(function (event) {
event.preventDefault();
form = $(this);
$.ajax({
type: 'POST',
url: form.attr('action'),
data: form.serializeArray()
}).done(function (result) {
if(result.object == 'success'){
$('#hidden-pdf-link').attr('href', result.link);
form.remove();
alert('you can access the pdf')
} else {
alert('you are not allowed to access my pdf!!');
}
})
});
});
</script>