Redirecting to 404 page from WordPress plugin

Question

I am trying to redirect the user to the theme 404.php template from a custom plugin if certain products are not found. Any ideas on this?

protected function get_id() {
    $product_id = $_GET['product_id'];

    $product = get_post( $product_id );

    if ( empty( $product ) ) {
        // Time to 404.
        $error_page = get_404_template();
        header("HTTP/1.0 404 Not Found");

        include($error_page);

       // neither works

        get_template_part('404');

        die();
    }
    else {
        $this->product_id = $product_id;
    }


}

Answer 1

Here's your updated code, it should properly show 404 page:

protected function get_id() {
    $product_id = $_GET['product_id'];

    $product = get_post( $product_id );

    if ( empty( $product ) ) {
        // Time to 404.
        global $wp_query;
        $wp_query->set_404();
        status_header( 404 );
        get_template_part( 404 ); exit();
    }
    else {
        $this->product_id = $product_id;
    }


}

Let me know if that does help.