nginx-examples/includes.d/to-slash-redirect.conf

error_page 419 = @redirectoToSlash;
set $is_admin_area "0";
if ( $request_uri ~* ^/admin.*$ ) {
    set $is_admin_area "${is_admin_area}1";
}
if ( $request_uri ~* ^.*ajax.*$ ) {
    set $is_admin_area "${is_admin_area}1";
}
if ( $request_uri ~* ^[^\?\.]*[^/](|\?.*)$) {
    set $is_admin_area "${is_admin_area}0";
}
if ( $is_admin_area = "00" ) {
    return 419;
}
location @redirectoToSlash {
    rewrite ^(.*[^/])$ $1/ permanent;
}