Author: Drew Jaynes

A couple of times in the last several years, I’ve needed sub-categories to inherit their parent’s archive template, but it’s just not something the Template Hierarchy supports. I’ve seen several plugins that tried and failed to do it, so finally I wrote a little filter that in my testing, works any number of levels deep, from sub-sub-categories to sub-sub-sub-categories. Enjoy!

function new_subcategory_hierarchy() {	
	$category = get_queried_object();

	$parent_id = $category->category_parent;

	$templates = array();
	
	if ( $parent_id == 0 ) {
		// Use default values from get_category_template()
		$templates[] = "category-{$category->slug}.php";
		$templates[] = "category-{$category->term_id}.php";
		$templates[] = 'category.php';		
	} else {
		// Create replacement $templates array
		$parent = get_category( $parent_id );

		// Current first
		$templates[] = "category-{$category->slug}.php";
		$templates[] = "category-{$category->term_id}.php";

		// Parent second
		$templates[] = "category-{$parent->slug}.php";
		$templates[] = "category-{$parent->term_id}.php";
		$templates[] = 'category.php';	
	}
	return locate_template( $templates );
}

add_filter( 'category_template', 'new_subcategory_hierarchy' );