Вывод основной категории записи (для Yoast SEO)

<?php
 $one_category = get_the_category(); 
 echo $one_category[0]->cat_name;
?>

<?php 
// SHOW YOAST PRIMARY CATEGORY, OR FIRST CATEGORY
$category = get_the_category();
$useCatLink = true;
// If post has a category assigned.
if ($category){
	$category_display = '';
	$category_link = '';
	if ( class_exists('WPSEO_Primary_Term') )
	{
		// Show the post's 'Primary' category, if this Yoast feature is available, & one is set
		$wpseo_primary_term = new WPSEO_Primary_Term( 'category', get_the_id() );
		$wpseo_primary_term = $wpseo_primary_term->get_primary_term();
		$term = get_term( $wpseo_primary_term );
		if (is_wp_error($term)) { 
			// Default to first category (not Yoast) if an error is returned
			$category_display = $category[0]->name;
			$category_link = get_category_link( $category[0]->term_id );
		} else { 
			// Yoast Primary category
			$category_display = $term->name;
			$category_link = get_category_link( $term->term_id );
		}
	} 
	else {
		// Default, display the first category in WP's list of assigned categories
		$category_display = $category[0]->name;
		$category_link = get_category_link( $category[0]->term_id );
	}
	// Display category
	if ( !empty($category_display) ){
	    if ( $useCatLink == true && !empty($category_link) ){
		echo '<span class="post-category">';
		echo '<a href="'.$category_link.'">'.htmlspecialchars($category_display).'</a>';
		echo '</span>';
	    } else {
		echo '<span class="post-category">'.htmlspecialchars($category_display).'</span>';
	    }
	}
 
}
?>

function get_post_primary_category($post_id, $term='category', $return_all_categories=false){
    $return = array();
 
    if (class_exists('WPSEO_Primary_Term')){
        // Show Primary category by Yoast if it is enabled & set
        $wpseo_primary_term = new WPSEO_Primary_Term( $term, $post_id );
        $primary_term = get_term($wpseo_primary_term->get_primary_term());
 
        if (!is_wp_error($primary_term)){
            $return['primary_category'] = $primary_term;
        }
    }
 
    if (empty($return['primary_category']) || $return_all_categories){
        $categories_list = get_the_terms($post_id, $term);
 
        if (empty($return['primary_category']) && !empty($categories_list)){
            $return['primary_category'] = $categories_list[0];  //get the first category
        }
        if ($return_all_categories){
            $return['all_categories'] = array();
 
            if (!empty($categories_list)){
                foreach($categories_list as &$category){
                    $return['all_categories'][] = $category->term_id;
                }
            }
        }
    }
 
    return $return;
}

<?php
$post_categories = get_post_primary_category($post->ID, 'category'); 
$primary_category = $post_categories['primary_category'];
echo $primary_category->name;
?>