show only terms from parent category

Question

i have a code which shows random posts from the same categories on the category-page. I use child and parent categories and i only want so show post from the same child-category or the same parent-category. At the Moment the code shows both (posts from parent and child-category) on the child-category-page. I didn't find a solution to fix this problem. I tried with

get_terms( array('parent' => 0 ) ); 

and also other ways. can somebody help me?

/*recent posts*/
function my_posts_from_category( $atts, $content = null ) {
    extract(shortcode_atts(array(
        'count' => 5,
        'verbose' => '0'    // '1' outputs some debug info
    ), $atts));
    $verbose = ( $verbose !== '0' );

    $content = '';

    $current_categories = array();
    global $post;
    if ( !empty( $post ) ) {
        // get all categories of current post
        $terms = get_the_terms( $post->ID, 'category', 'orderby=count&hide_empty=0&parent=0');
        if ( $terms && !is_wp_error( $terms ) ) {
            foreach( $terms as $term ) {
                /*if ($_term->parent == 0) //check for parent terms only*/
                $current_categories[] = $term;
            }
        }
    } else {
        if ( $verbose ) $content = 'posts_from_category: no $post...';
    }

    foreach ( $current_categories as $category ) {

        // get all tags of current post
        $found_terms = array();
        $terms = get_the_terms( $post->ID, 'post_tag' );
        if ( !is_wp_error( $terms ) && !empty( $terms ) ) {
            foreach ( $terms as $term ) {
                $found_terms[] = $term->term_id;
            }
        }

        // list of ids to exclude, first entry: current post
        $my_exclude_ids = array( $post->ID );

        // ids of related posts of current post
        $my_related_post_ids = array();

        foreach ( $found_terms as $found_term ) {
            // get one post with found tag ordered by random
            $args = array(
                'posts_per_page' => 1,
                'orderby' => 'rand',
                'tax_query' => array(
                    array(
                        'taxonomy' => 'post_tag',
                        'field' => 'id',
                        'terms' => $found_term
                    )
                ),
                'suppress_filters' => false,
                'fields' => 'ids',
                'post__not_in' => $my_exclude_ids   // exclude already found posts
            );
            $my_related_post_id = get_posts( $args );   // actually max. 1 post
            if ( !empty( $my_related_post_id ) ) {
                $my_related_post_ids = array_merge( $my_related_post_ids, $my_related_post_id );
                $my_exclude_ids = array_merge( $my_exclude_ids, $my_related_post_id );
            }
        }

        // get all post ids of current category ordered by date
        $args = array(
            'posts_per_page' => -1,
            'orderby' => 'post_date',
            'order' => 'DESC',
            'tax_query' => array(
                array(
                    'taxonomy' => 'category',
                    'field' => 'id',
                    'terms' => $category->term_id
                )
            ),
            'suppress_filters' => false,
            'fields' => 'ids',
            'post__not_in' => $my_exclude_ids   // exclude current post
        );
        $my_post_ids = get_posts( $args );
        // result could be empty if all found were also related before

        // combine results
        $my_post_ids = array_merge( $my_post_ids, $my_related_post_ids );

        // mix results in random order, todo, array_splice(len=0)?
        shuffle( $my_post_ids );

        $posts_lis = array();
        foreach ( $my_post_ids as $my_post_id ) {
            // add a post
            $posts_lis[ 'id_' . $my_post_id ] = '<li><a href="' . get_permalink( $my_post_id ) . '" title="' . esc_attr( get_the_title($my_post_id ) ) . '">' . get_the_title($my_post_id ) . '</a> (' . get_the_date( get_option( 'date_format' ), $my_post_id ) . ')</li>';
            // limit output
            if ( count( $posts_lis ) >= $count ) {
                break;
            }
        }

        // build html container
        $content .= '<div class="posts-from-category posts-from-category-' . $category->slug . '">';
        $content .= '<p>Bei Lesern der Kategorie <a href="' . esc_url( get_term_link( $category->slug, 'category' ) ) . '">' . $category->name . '</a> ebenfalls beliebt:</p>';
        $content .= '<ul>';
        $content .= implode( $posts_lis );
        $content .= '</ul>';
        $content .= '</div>';
    }
    return $content;
}

Answer 1

Use this line of code for listing categories.

   $terms_list = get_terms(array('taxonomy'=>'category', 'hide_empty'=>FALSE, 'parent'=>0));
   print_r($terms_list);