Wordpress admin-ajax.php is dying "0" without processing function

Question

I am trying to learn how to process AJAX requests in Wordpress the correct way. To do this I am adapting this tutorial to create a super simple AJAX request to place the ID of a post (from a link) into my page content.

The Logic

1. When the #our-work a links are clicked [js]
2. Get the post ID (from the data-id attribute) & store it as postID variable [js]
3. Pass postID via an AJAX (using the WP's admin-ajax.php file) [js]
4. The example_ajax_request function will pick up the ID & simply echo it [php]
5. If successful, append the server response to the #hero div.

I realise this has no benefit but once I have that working I will amend the function to serve a real purpose.

My Code

Here is a copy of the function I have created in the plugins folder:

wp_enqueue_script( 'my-ajax-request', plugin_dir_url( __FILE__ ) . 'acl-plugin.js', array( 'jquery' ) );

wp_localize_script( 'my-ajax-request', 'MyAjax', array( 'ajaxurl' => admin_url( 'admin-ajax.php' ) ) );

function example_ajax_request() {
    if ( isset($_REQUEST) ) {
        $postID = $_REQUEST['postID'];
        echo $postID;
    }
    die();
}
add_action( 'wp_ajax_nopriv_example_ajax_request', 'example_ajax_request' );

And here is a copy of the JS file

jQuery(document).ready(function($) {
    $('#our-work a').click( function() {
        var postID = $(this).attr("data-id");

        $.ajax({
            url: MyAjax.ajaxurl,
            data: {
                'action':'example_ajax_request',
                'postID' : postID
            },
            success:function(data) {
                $('#hero').append( "Well this seems to work" + data );
            },
            error: function(errorThrown){
                console.log("This has thrown an error:" + errorThrown);
            }
        });
        return false;
    });
});

The Problem

Upon clicking the link the JS does fire but yields the following response:

<div id="hero">
    Well this seems to work 0
</div>

Using an alert I know the ID is being picked up before the AJAX request. So the problem is in my function. To find out more, I (temporarily) tweaked WP's admin-ajax.php file, so that I could find out which die(); was yielding the response of "0".

It is the very last one in the file which I thought wouldn't fire as I have a die(); command in my own function. Can someone please point out where I am going wrong?

Answer 1

This is one of those rare times I can proudly say... there isn't any problem here!

The reason the server is returning with 0 is because I was logged in! The wp_ajax_nopriv_example_ajax_request is only for users who are not logged in. After logging out this works fine.

So if you are looking to do the same thing, just make sure you have both actions below the function:

add_action( 'wp_ajax_example_ajax_request', 'example_ajax_request' );
add_action( 'wp_ajax_nopriv_example_ajax_request', 'example_ajax_request' );