wordpress - Category page should not display child categories

Question

I need that each category of Wordpress will display only its own posts and not those of its child categories. How is this done?

I need posts that are in sub-categories to appear only in their sub-categories and not to appear in the parent category (where I want to see only posts that were marked for that parent category. However, in the parent category I get all posts that are marked to appear in the sub-category of that parent category.

For example, if I have category "cars" and underneath it, subcategories "Fiat", Ford", "Honda", I see the Fiat posts both in the subcategory "Fiat" and in the parent category "Cars".

How can we fix that?

Answer 1

Make use of the parse_tax_query action to exclude children of the current category

You can try something like this: (Requires php 5.3 +)

add_action( 'parse_tax_query', function ( $query ) {
    if ( 
        ! is_admin() 
        && $query->is_main_query()
        && $query->is_category()
    ) {
        $query->tax_query->queries[0]['include_children'] = 0;
    }
});

Answer 2

Works only with WordPress >= 3.3.

In your functions.php theme file:

add_filter('pre_get_posts','hide_subcategories_function',20,1);

function hide_subcategories_function($the_query) {
    if(get_bloginfo('version') >= 3.3 && function_exists('is_main_query')) {

        if(!$the_query->is_admin && !$the_query->is_preview && $the_query->query_vars['suppress_filters'] == false && $the_query->is_category && $the_query->is_main_query()) {

            $cat = get_term_by( 'slug', $the_query->query_vars['category_name'], 'category');

            $the_query->set('category__in',array($cat->term_id));

        }

    }
    return $the_query ;
}