Redirection of users away from wp-admin (but not administrators)

Question

I want to redirect all users except the admin away from the wp-admin page.
If the logged in user tries to access /wp-admin then they will be redirected back home.
Right now they get a page that says "Sorry you are not allowed to access this page"
Can y'all please help me construct a function in my functions.php file to check for these conditions and redirect?
This is what I have, and it isn't working for what I want.

function acme_login_redirect( $redirect_to, $request, $user  ) {
  return ( is_array( $user->roles ) && in_array( 'administrator', $user->roles ) ) ? admin_url() : site_url();
}
add_filter( 'login_redirect', 'acme_login_redirect', 10, 3 );

Answer 1

Here's how I do this:

// if admin send them to the dashboard, otherwise leave them on the frontend
add_action('wp_login', 'rt_login_redirect', 10, 2);  //use this action if you want them to be redirected only after login but leave the ability to to to the dashboard later (ie changing profile or pw).
add_action( 'admin_init', 'rt_login_redirect' ); // use this action to completely dis-allow all others besides the admin to access the dashboard.
function rt_login_redirect($user_login, $user) {

    if  (!current_user_can('manage_options')) {
            wp_safe_redirect( home_url(), 302);
            exit();
    }
}

The main function checks if the users is an admin by checking if the users has the ability to manage options. If they don't have that capability then the function will redirect them to the homepage. If they do they can stay on the backend.

The function is activated when someone try to take an action (as commented above) (chose an option based on what you want)