为什么 get_query_var 不返回我的自定义查询变量？

Question

I am building a WP plugin which defines some extra URLs, query vars and templates.

I want to use get_query_var("wps_service_id"); in my templates, but it is returning nothing no matter what I do.

I have whitelisted the extra query vars like the documentation explains :

add_filter('query_vars', function ($query_vars) {
    $query_vars[] = 'wps_service_id';
    return $query_vars;
});

I am defining my extra URLs and loading the correct template like this:

add_action('init',  function () {
    add_rewrite_rule(
        'services/([a-z0-9-]+)/?$',
        'index.php?wps_service_id=$matches[1]',
        'top'
    );
});


add_action('parse_request', function (&$wp) {
    if (array_key_exists('wps_service_id', $wp->query_vars)) {
        require plugin_dir_path(__DIR__) . "views/service.php";
        exit();
    }
    return;
});

The template is loading, so WP is clearly reading and interpreting the query vars to some extent. Why can't I read it and use it in the template using get_query_var ?

Answer 1

Is it correct to use 'array_key_exists'? You should use 'in_array', because you assign a value not a key in $query_vars[] = 'wps_service_id';

Check with:

error_log( array_key_exists('wps_service_id', $wp->query_vars));
error_log( in_array('wps_service_id', $wp->query_vars));