AJAX and do_shortcode

Question

I know questions on this subject have been asked before. But I'm stuck and cannot find a way out.

I am using Ajax to load external information to my site. Initially all the information was loaded at once, but because of the large amount of data Ajax became a necessity.

The information is accessed from an external CMS, using a plugin developed by a 3rd party.

In the Ajax I have to use the plugin's do_shortcode. But it fails. No results are returned. When it is directly put in a page template's code it works flawlessly.

I have used the best practices I found to create the Ajax communication (i.e., use wp_ajax and wp_ajax_nopriv for the callbacks, registering, enqueueing, and localization of JS scripts).

I tested the Ajax connection and I can send messages back and forth. But as stated, the shortcode is the one thing that always fails.

I haven't been able to reach to the plugin developer. So I'm asking if there are any other things I should be aware of when trying to use shortcodes with wp_ajax.

Thanks in advance.

EDIT: I'm adding code so that it can help:

in functions.php

//  AJAX HOOKS TO LOAD PRODUCTS' INFO
add_action('wp_ajax_get_product_info', 'get_product_info' );
add_action('wp_ajax_nopriv_get_product_info', 'get_product_info' );

// SHOULD RUN SHORTCODE TO GET PRODUCT INFORMATION AND SEND IT BACK TO JS SCRIPT
function get_product_info() {
   //Checks the nonce and kills the script if wrong
   $nonce = $_POST['nonce'];
   if ( ! wp_verify_nonce( $nonce, 'return_posts' ) )
        die ( 'Wrong nonce!');
   //Process Info
   $pid = $_POST['product_id'];   
   header('Content-type: text/html');

   // Returns the shortcode
   echo do_shortcode("[ps_product_list id_product=".$pid." tpl=product-grid-exclusives.tpl]");

    // We don't want anything else to run
   exit;
}

// REGISTERS, LOADS & LOCALIZES product-store-ajax.js
if (!function_exists('load_scripts')) {
    function load_scripts() {

        if ( !is_admin() && is_category('teaser-online-exclusives') ) {

                wp_register_script( 'product-ajax', get_stylesheet_directory_uri().'/js/product-store-ajax.js', array( 'jquery' ), '', true );

                wp_enqueue_script('product-ajax');

                wp_localize_script( 
                    'product-ajax', 
                    'productajaxvars', 
                    array( 
                        'ajax_url' =>  admin_url( 'admin-ajax.php' ), 
                        'nonce'    =>  wp_create_nonce( 'return_posts' ),
                        'callback' => 'get_product_info'
                    ) 
                );
        }
    }
}
add_action('wp_enqueue_scripts', 'load_scripts');

And the JS file:

(function( $ ) {
    $(function() {

        $.ajax({
            url:  productajaxvars.ajax_url,
            data: { 
                action:  productajaxvars.callback,  // callback defined in functions.php
                nonce :  productajaxvars.nonce,
                product_id: 82},
                success: function( response ) {
                            alert(response);
                },
                type: "POST",
        });


    });
})( jQuery );

Answer 1

Ajax runs without a main WP_Query object and therefor all its APIs that are used to determine the type of page that is being displayed. The code which is responsible for outputting the result of the shortcode is probably checking for is_single() to be true so it will not add output to archive pages.

What you can do is to create a main query object, but it will probably be just faster to look at the code that generates the shortcode and find out if there is a simple function you can calll to do what you need.

A note about your general strategy - you are going to overload your sever with uncachable requests. If you have the CPU to spare or it is just one page, then there is probably no problem with that, but otherwise be very careful with what you do.