get_categories returns top-level categories instead of child categories

Question

I've made a basic subcategory nav menu using the code below.

The problem is on one category (with NO children), it returns the Top Level categories as children, e.g.: News, Uncategorized, etc. (I've tried assigning a child category and it actually disappears from the menu instead of fixing things)

What could be causing this?

function display_category_breadcrumbs () {
    $current_cat_id = get_cat_id( single_cat_title("",false) );    
    $parent_cats = get_categories('parent='.$current_cat_id);  

    ?> <ul id="cat-breadcrumb"> <?php
    foreach ($parent_cats as $sub_category ) {
        echo '<li><a href="'. esc_url( get_category_link( $sub_category->term_id) ) . '">' . esc_html( $sub_category->cat_name) . '</a></li>';
    }
    ?> </ul> <?php
}

Answer 1

I believe what you're seeing is the expected behavior when parent is set to 0 which is what get_cat_id() returns if it fails to find a category ID for the $cat_name argument. You can quickly test this by putting var_dump($current_cat_id); anytime after you set it to see if this guess is right. If so, you'll need to figure out why you're not getting a $current_cat_id.

The way you're doing it right now strikes me as fairly error-prone though it's hard to know without more context. I'd look to get the ID directly from a get_the_terms() if you're on single posts or maybe with get_query_var() if on a term archive page.

Tangentially, your code shouldn't be working at all if what you pasted is unedited since your if statement has no test to perform.