How do I get the parent category if I know the child category?

Question

So Ive got this function here that creates a drop-down menu from only the child categories, it works great.

The problem is that I need to get the parent categories name and assign it as the value of the option class for the child category menus. I can't seem to get it to work, all I get is either '/' or '/child_Category_name/'

Thanks!

function child_dropdown($dropID, $taxonomy, $exclude) {

$args = array(
'orderby'                  => 'name',
'order'                    => 'ASC',
'hide_empty'               => 0,
'hierarchical'             => 1,
'exclude'                  => $exclude,
'taxonomy'                 => $taxonomy,
'pad_counts'               => false );




$categories = get_categories( $args );

$menu = '<select name="'.$dropID.'" id="'.$dropID.'" class="postform">';
$menu .='<option value="">--</option>';

foreach($categories as $category)
{
    if($category->parent != 0 ) {

        $menu .= '<option class="'.get_category_parents().'" value="'.$category->name.'">'.$category->name.'</option>';
    }
}   
$menu .= '</select>';
echo $menu;

}

Answer 1

get_category_parents() requires the category ID to be passed as the first parameter, and returns an array a string of all the parents, separated by / by default. You can change this to a space to include them in your class list:

foreach ( $categories as $category ) {
    // Get the parents, separated by a space
    $parents = get_category_parents( $category->id, false, ' ' );

    // If $parents isn't an error, carry on
    if ( ! is_a( $parents, 'WP_Error' ) ) {
        $menu .= '<option class="' . $parents . '" value="' . $category->name . '">' . $category->name . '</option>';
    }
}

If you want to get all sorts of kooky, you can also print out your HTML like thus:

$menu .= sprintf( "<option class='%s' value='%s'>%s</option>",
                  esc_attr( $parents ),
                  esc_attr( $category->name ),
                  esc_attr__( $category->name )
         );