Ajax call not working anymore

Question

I had a few functions I was calling with ajax...basically, everything was working as expected and now it's not. I'm not sure what could be causing this problem.

I have a button on my page like so:

<p class='form-submit' method='post'>
    <input id='$message_id' name='message_read' type='button' onclick=hideMessage($message_id) class='submit button mark-as-read' value= 'Mark as read' />
</p>

When I click the button, the following ajax code executes from js/wp-ajax-calls.js

    jQuery(document).ready(function() { 

       jQuery(".mark-as-read").click(function () {
          console.log('mark as read ajax called');
         jQuery.ajax({
             type: "POST",
             url: "/wp-admin/admin-ajax.php",
             data: {
                action: 'mark_message_as_read',
                message_id: this.id
                 }
             success: function (msg) {
                  console.log('action was successful');
                  console.log(msg);
             },
             error: function (errormessage) {
                  console.log(errormessage);
              }
        });
    });
});

I see the console message I put in there when I click the button.

In my functions.php I have the following function:

add_action('wp_ajax_mark_message_as_read', 'mark_message_as_read');
function mark_message_as_read() {
    echo "<script>console.log('the message function is called');</script>";
    //do stuff
}

I do not see the second console message.

When I check the network tab on my browser, I can see that the ajax requests are generating a 302 response.Interestingly enough, when I log in to my site as the admin user, I get a 200 response and the site behaves exactly as I expect with no issues. I only get the 302 response when I am logged in as a subscriber.

Here are the response headers when I'm logged in as a subscriber:

Access-Control-Allow-Credentials: true
Access-Control-Allow-Origin: https://localhost
Cache-Control: no-cache, must-revalidate, max-age=0
Connection: Keep-Alive
Content-Length: 1
Content-Type: text/html; charset=UTF-8
Date: Wed, 31 Oct 2018 05:32:40 GMT
Expires: Wed, 11 Jan 1984 05:00:00 GMT
Keep-Alive: timeout=5, max=100
Location: https://localhost/
Referrer-Policy: strict-origin-when-cross-origin
Server: Apache/2.4.18 (Ubuntu)
Strict-Transport-Security: max-age=63072000; includeSubdomains
X-Content-Type-Options: nosniff
X-Content-Type-Options: nosniff
X-Frame-Options: DENY
X-Frame-Options: SAMEORIGIN
X-Robots-Tag: noindex

The 'success' always callback gets called from the original ajax request, no matter who I am logged in as.

Happy to provide more info if needed.

Thanks!

Answer 1

I figured it out using this previous post:

Issue with front-end ajax, getting a 302 redirect when accessing wp-admin/admin-ajax.php

Basically, I had added an action to prevent subscribers from seeing certain wordpress pages.

  function limit_subscriber_access() {
    $redirect = home_url( '/' );
    if ( ! ( current_user_can( 'manage_options' ) || current_user_can( 'edit_posts' ) ))
        exit( wp_redirect( $redirect ) );
}

This was causing the 302 redirect and preventing the $wpdb related code from executing. Here is what I added:

  function limit_subscriber_access() {
    $redirect = home_url( '/' );
    if ( ! ( current_user_can( 'manage_options' ) || current_user_can( 'edit_posts' ) ) && !defined('DOING_AJAX'))
        exit( wp_redirect( $redirect ) );
}

I tested and it seems to be working how I wanted.

Thanks to everybody who helped me try to figure it out!