How To Get The Primary Category Of A Post Only - Reusable Function

First off, whether a post should have multiple categories or not is for another discussion. The answer is no….I mean…

Second, and more importantly, the functions the_category and get_the_category both return a list of categories. When we select more than one category in a post we get this option to make one of them primary.

But often the need arises to restructure a breadcrumb, post meta layout, etc. and we just want to get the primary category of a post only.

Here’s how to do it:

How to get the primary category of a post only

Shoutout to Jawinn for the actual code. All I did was “functionize” it to make it reusable.

So the function gets one parameter, the list of categories. So whenever using it, be sure to call the get_the_category function beforehand and then place the results in a variable which will be passed to the function.

To make it reusable, place the function in your functions.php, or more preferably in a custom plugin.

function get_primary_category($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) ){
      return '<span class="post-category"><a href="'.$category_link.'">'.htmlspecialchars($category_display).'</a></span>';
      } else {
      return '<span class="post-category">'.htmlspecialchars($category_display).'</span>';
      }
    }
  }
}
    </code>
</pre>

// And for an example of its use:
$category = get_the_category();

echo '<div class="post-category">';
echo get_primary_category($category);
echo '</div>';

Conclusion

And that’s how to get the primary category of a post in a reusable function!!