Ajax returning 400 Bad Request (xhr), admin-ajax.php returns '0'?

Question

So I have limited experience with Ajax and I'm not entirely sure how to debug/resolve the issue. The error in question is;

admin-ajax.php - 400 Bad Request (xhr).

I have checked the resource loaded and I can get a response of '0'. Looking into it I can see that a '0' response means either that the action is not set (in the ajax data) or that the action's callback function cannot be found.

Seeing as I have set an action I can only assume this is because the call back function cannot be found. But checking the code theres no typos in the callbacks?

Any help I could get would be much appreciated.

functions.php

add_action('wp_head', function(){   
    require_once( get_stylesheet_directory() .'/inc/better-comments.php' );
    require( get_stylesheet_directory() .'/inc/ajax.php' );
});

ajax.php

if ( ! defined( 'ABSPATH' ) ) {
    exit; // Exit if accessed directly.
}

add_action('wp_ajax_nopriv_front_load_more', 'front_load_more');
add_action('wp_ajax_front_load_more', 'front_load_more');

function front_load_more() {
    
    global $post;
    $post = get_post( $_POST['post_id'] );
    setup_postdata( $post );
    
    wp_list_comments( array( 'callback' => 'better_comments' ) );
    
    die();
    
};

theme.js

jQuery(document).ready(function($){
    $(document).on('click', '.front-load-more', function(){
    
        var button = $(this);
 
        // decrease the current comment page value
        cpage--;
        
        $.ajax({
            url : ajaxurl, // AJAX handler, declared before
            data : {
                'action' : 'front_load_more',
                'post_id': parent_post_id, // the current post
                'cpage' : cpage, // current comment page
            },
            type : 'POST',
            beforeSend : function ( xhr ) {
                button.text('Loading...'); // preloader here
            },
            success : function( data ){
                if( data ) {
                    $('ol.comment-list').append( data );
                    button.text('More comments'); 
                     // if the last page, remove the button
                    if ( cpage == 1 )
                        button.remove();
                } else {
                    button.remove();
                }
            }
        });
        return false;
        
    });
});

comments.php (the trigger)

<?php   
  $cpage = get_query_var('cpage') ? get_query_var('cpage') : 1;
 
  if( $cpage > 1 ) {
    echo '<a class="btn btn-block btn-soft-primary transition-3d-hover front-load-more">Load More</a>
       <script>
       var ajaxurl = \'' . admin_url('admin-ajax.php') . '\',
            parent_post_id = ' . get_the_ID() . ',
            cpage = ' . $cpage . '
       </script>';
   }
?>

Amended - add_action('wp_ajax_nopriv_front_load_more', 'front_load_more');

Amended - add_action('wp_ajax_front_load_more', 'front_load_more');

EDIT: 21 Jan 15:23 As @cabrerahector said, I had code within my ajax.php file that needed to be moved to my functions.php file. This resolved the bad request issue.

There's a difference between front-load-more and front_load_more. Stick to underscores. Also, are you sure you want to use the admin-url? Does the feature require the user to be a logged in admin? — M. Eriksson
– M. Eriksson, Commented Jan 20, 2019 at 22:03
I didn't think the css handle would matter? Is that not the case? Also no the feature has add_action('wp_ajax_nopriv_front-load-more', 'front-load-more'); assigned so I thought that would negate the issue. — Lewis
– Lewis, Commented Jan 20, 2019 at 22:15
I notice what you mean, within the add_action handles. (Took me a sec.) I've amended this and the error persists no change. — Lewis
– Lewis, Commented Jan 20, 2019 at 22:27
The code you have in ajax.php should be in functions.php instead. — cabrerahector
– cabrerahector, Commented Jan 21, 2019 at 0:42
Done! Regarding the empty response issue, you should open a new question for this. However, I noticed in your code that apparently parent_post_id hasn't been initialized anywhere. — cabrerahector
– cabrerahector, Commented Jan 21, 2019 at 16:01

cabrerahector · Accepted Answer · 2019-01-21 16:00:25Z

2

The problem is that the code you have in ajax.php should be in functions.php instead: your wp_ajax_* action hooks aren't being correctly registered by WordPress, hence the 400 Bad Request response you're seeing.

answered Jan 21, 2019 at 16:00

cabrerahector

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1 Comment

Lewis Over a year ago

Thanks buddy, spot on!

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