Filter Custom Post Type by Category with Ajax

Question

I've used the below tutorial for my WordPress site to add a filter to one of the pages.

https://www.youtube.com/watch?v=KRc47o8uDhk&list=PLSeCxQ7f7r87qbYmqXmOAcvoshw1e6ewQ&index=3

It works well when adding the code as is. However, I need it to instead work with a custom post type 'libraries' and custom taxonomies 'library_types'.

I replaced $categories = get_categories($cat_args); with $categories = get_terms( 'library_types' );, which now shows the correct taxonomies. And also changed 'post-type'=> 'post' to 'libraries'. However it now returns no results. What other variables need to change in order for this to work?

Original Github below.

https://github.com/guyku/WordPressAjax_RyanMcGovern_Lesson

EDIT:

I figured it's probably the filter_ajax that needs adjusting. So I've tried the following:

$category = $_POST['category'];
//$category = get_cat_ID($_POST['library_types']);
//$category = get_post_meta('library_types');
//$category = get_term_meta('library_types');
//$category = get_terms( 'library_types' );

I know it's correctly parsing the ID number because I'm able to echo it through $category, but it's just not displaying any results.

If I use the bottom line instead $category = get_terms( 'library_types' ); then it sort of works but only shows the category items with the highest ID number.

Would appreciate any insight.

Page content:

<!-- Filter -->
        <div class="categories">
            <ul>
            <?php 
            //$cat_args = array(
            //  'exclude' => array(1),
            //  'option_all' => 'All'
            //);

            //$categories = get_categories($cat_args);
            $categories = get_terms( 'library_types' );

            foreach($categories as $cat) : ?>
                <li class="js-filter-item"><a data-category="<?= $cat->term_id; ?>" href="<?= get_category_link($cat->term_id); ?>"><?= $cat->name; ?></a></li>
            <?php endforeach; ?>
            </ul>
        </div>
        
        
        <!-- Display all library post types -->
        <div class="library-wrapper">
            <div class="js-filter">
                <?php

                $args = array(
                    'post_type' => 'libraries',
                    'posts_per_page' => -1
                    );

                    $query = new WP_Query($args);

                    if($query->have_posts()) :
                        while($query->have_posts()) : $query->the_post();
                            the_title('<h2>', '</h2>');
                            get_post_meta('library_types');
                            get_cat_ID('library_types');
                        endwhile;
                    endif;
                    wp_reset_postdata(); ?>
            </div>
        </div>

JS Content:

    function($){

    $(document).ready(function(){
        $(document).on('click', '.js-filter-item > a', function(e){
            e.preventDefault();

            var category_var = $(this).data('category');

            $.ajax({
                url: wp_ajax.ajax_url,
                data: { action: 'filter', category: category_var },
                type: 'post',
                success: function(result) {
                    $('.js-filter').html(result);
                },
                error: function(result) {
                    console.warn(result);
                }
            });
        });
    });

})(jQuery);

Functions content:

    function load_scripts() {
    wp_enqueue_script('ajax', get_theme_file_uri() . '/sorting.js', array('jquery'), NULL, true);
    
    wp_localize_script('ajax' , 'wp_ajax',
        array('ajax_url' => admin_url('admin-ajax.php'))
        );

}

add_action( 'wp_enqueue_scripts', 'load_scripts');


add_action( 'wp_ajax_nopriv_filter', 'filter_ajax' );
add_action( 'wp_ajax_filter', 'filter_ajax' );

function filter_ajax() {


$category = $_POST['category'];
//$category = get_cat_ID($_POST['library_types']);
//$category = get_post_meta('library_types');
//$category = get_term_meta('library_types');
//$category = get_terms( 'library_types' );

$args = array(
        'post_type' => 'libraries',
        'posts_per_page' => -1
        );

        if(isset($category)) {
            $args['category__in'] = array($category);
            echo $category;
        }

        $query = new WP_Query($args);

        if($query->have_posts()) :
            while($query->have_posts()) : $query->the_post();
                the_title('<h2>', '</h2>');
            endwhile;
        endif;
        wp_reset_postdata(); 


    die();
}

Answer 1

Nevermind, I've managed to solve it. For anyone interested, the problem was 'category__in' isn't support by custom post types so instead needed to edit the $args array to include 'tax_query'.

$args = array(
        'post_type' => 'libraries',
        'tax_query' => array(
            array(
                'taxonomy' => 'library_types',
                'terms'    => $category
            ),
        ),
    );