Get_term_meta() does not work with pre_get_posts()

Question

I am trying to get custom term meta value for a certain category using get_term_meta() function. This value is stored in the wp_termmeta table. Then, based on that value, I want to modify the main query for a certain category archive page (sort the posts by date ascending). However, the pre_get_posts() hook that I am using does not allow me to do so. I tried all the ways that i am aware of, however, it is still not working

Here is my code:

function my_new_category_order( $query ) {
    //get the category id
    $cat_id = get_query_var('cat');
    //get the custom meta value
    $post_order = get_term_meta($cat_id, 'post-order', true);
    //The value is shown two times. First, it is false, then it is "oldest"
    var_dump($post_order); 

    //Cannot go inside the if statement because $post_order is false!
    if ( $post_order && $query->is_category($cat_id) && $query->is_main_query() ) {
        $query->set( 'order', 'ASC' );
        //$post_order is false here
        var_dump($post_order);
        //$cat_id is empty string
        var_dump($cat_id);
    }


}
add_action( 'pre_get_posts', 'my_new_category_order' );

As a result, I am not able to go inside the if statement and reorder the posts.. The rest of the code is working fine but the term meta value remains undefined. What am I doing wrong?

Answer 1

I finally, finally figured it out! I was not able to get the category id in the first place. Strangely, get_query_var('cat') is not working. Here is the way that worked for me, in case someone else also struggles with this:

function my_new_category_order( $query ) {
    $category = get_queried_object();
    $cat_id = $category->term_id;
    $post_order = get_term_meta($cat_id, 'post-order', true);
    //Now everything works!
    if ( $post_order =='oldest' && $query->is_category($cat_id) && $query->is_main_query() ) {
        $query->set( 'order', 'ASC' );
    }
}
add_action( 'pre_get_posts', 'my_new_category_order' );