Loading post template that contains a nested loop with ajax

Question

I'm currently working on a project where I'm loading a post with ajax. I'm using get_post() to get the post, setup_postdata() to setup the post data, and get_template_part() to load the template containing the markup I want. My function looks like this:

public function get_content($url) {  

    global $post;

    $post_id = url_to_postid($url);

    if($post_id){

        $post = get_post($post_id);

        setup_postdata( $post );
            ob_start();
            get_template_part('template/page', 'default');
            $content = ob_get_contents();
            ob_end_clean();
        wp_reset_postdata();

        return array('status' => 'success', 'content' => $content);         

    } else {

        return array('status' => 'error','message'=> 'Fant ikke post til relevante url..');

    }   

    die();  

}

My template is containing a nested loop to display a catering menu based on categories. So I use get_categories() to get all the categories that have posts and then get_posts() to display the posts for parent category. My template looks like this:

<nav class="catering-nav">
<?php   
    $category_args = array(
        'type'                     => 'menus',
        'child_of'                 => 0,
        'parent'                   => '',
        'orderby'                  => 'name',
        'order'                    => 'ASC',
        'hide_empty'               => 1,
        'hierarchical'             => 1,
        'exclude'                  => '',
        'include'                  => '',
        'number'                   => '',
        'taxonomy'                 => 'catering_themes',
        'pad_counts'               => false 

    );      

    $categories = get_categories($category_args);

    if ( $categories ) { 

    echo '<ul id="catering-menu" class="list-unstyled catering-menu">';

        foreach ( $categories as $cat ) {   

            echo '<li class="has-children menu-item"><a href="' . THEME_URL . '/themes/' . $cat->slug .'/">' . $cat->name .'</a>';

            $menus_arg = array(
                'post_type' => 'menus',
                'order' => 'ASC',
                'orderby' => 'name',
                'post_status' => 'publish',
                'tax_query' => array(
                    array(
                        'taxonomy' => 'catering_themes',
                        'field' => 'slug',
                        'terms' => $cat->slug,
                    )
                ),              
                'posts_per_page' => -1
            );      

            $menus = get_posts( $menus_arg );

            if ( $menus ) { 

            echo '<ul class="list-unstyled sub-menu">';

                echo '<li class="menu-item menu-item-title"><span class="catering-nav-back">Tilbake</span><span class="catering-nav-title">' . $cat->name .'</span></li>';

                foreach ( $menus as $post ) : setup_postdata( $post );

                    echo '<li class="menu-item"><a href="' . get_the_permalink() . '">'. get_the_title() .'</a></li>';

                endforeach; 

                wp_reset_postdata();

            echo '</ul>';    

            } 

            echo '</li>';

        }

    echo '</ul>';    

    }       

?>  

</nav>

<!-- Title and Content from the get_post() -->
<article id="post-content">
        <div class="row">
            <div class="col-md-11">
                <h1 class="post-title"><?php the_title(); ?></h1>
            </div>
            <div class="col-md-1">
                <a id="content-close" class="button-close" href="#"></a>
            </div>          
        </div>  
        <div class="row">
            <div class="col-md-12">         
                <?php the_content(); ?>
            </div>      
        </div>  
</article>

The loop getting the catering menus is working great, but the title and content that are supposed to come from the post loaded with get_post() is showing the data from the last post loaded in the catering menu loop. Do some wordpress genius know why this is happening?

Answer 1

Your inner loop overwrites the contents of $post, so any later template tags use the values of whatever it last contained.

"But I used wp_reset_postdata()!" you say? What that function does is try to restore $post from $wp_query->post. It's meant to restore the main query after secondary queries. You have two secondary queries here, so that method fails.

To fix it- either use $wp_query as a new WP_Query instance for your outer loop, which will result in wp_reset_postdata() working as expected, or assign your outer post to some other variable name and don't use template tags that rely on the global $post.