Handling AJAX requests with expired authentication

The Problem:

When an ajax request is made from a page that requires a valid user (in the session), the page does not redirect (to a Login page) when the auth session has expired. This makes the page look unresponsive and provides a less than ideal user experience.

The Solution:

The solution is quite simple though not that obvious. It has 2 parts:

• The middleware will recognise the expired auth and that the request is ajax, then send a custom Response the page will recognise.

• The Javascript on the page will check the ajax response before it gets processes by other event handlres. If the response matches the criteria the browser redirects to the login page.

The Code:

Auth Middleware

In your AuthenticationMiddleware do something similar to the following

def before(self, request, response):
    if not request.user():
        if request.is_ajax():
            response.content = "MASONITE_LOGIN_REQUIRED"
            response.status(403)
            return response

        return response.redirect(name="login")

    return request

Page Template

Add the .ajaxComplete() block the document.ready javascript function in your page

$(document).ready(function() {
    $(document).ajaxComplete(
        function (event, request, options) {
            if (request.responseText === "MASONITE_LOGIN_REQUIRED") {
                window.location.href = "{{ route(name='login') }}";
            }
        }
    )
});

This is for JQuery but you can adjust this id for whatever JS framework you're using.

Middleware ordering

This adjustment is not strictly required but does provide a better user experience.

By default the VerifyCsrfToken middleware is set as part of the web middleware group. This will prevent the auth middleware checking the request before processing the page form data and may generate an invalid form error which is not what the user might expect.

To resolve this you can easily rearrange the order of middlewares.

In your Kernel.py file adjust the route_middleware similar to this:

route_middleware = {
    "web": [SessionMiddleware, LoadUserMiddleware],
    "auth": [AuthenticationMiddleware, VerifyCsrfToken],
...
}

NOTE: the VerifyCsrfToken comes AFTER the AuthenticationMiddleware. This means that in this example only the routes tagged as auth will check the csrf token in form data.

Notes:

• The MASONITE_LOGIN_REQUIRED can be anything you like, so making it a const of some kind is probably advisable to prevent issues with typos.

• The above javascript assumes you have a route named login