Identity Server 4: Redirect or Show Error Message in OnTokenValidated

Question

In my web application, after user authenticates w/ interactive login page, I would like to do some additional validation in OnTokenValidated after the user is authenticated, and if it fails then i want to show a nice page with an appropriate message.

How can I do this? I tried:

    private Task HandleOpenIdConnectOnTokenValidated(TokenValidatedContext context)
    {
        if (some condition fails...)
        {
                context.HttpContext.Response.Redirect("/home/notregistered");
                return Task.FromResult(-1);
            }
        }
        return Task.CompletedTask;
    }

Other option is to throw an exception, but it shows an unpleasant error. If this is best/only option, how can I specify a custom error page and show something custom based on the exception thrown?

thanks

Answer 1

I would implement the additional authorization requirements using the built in authorization mechanisms.

Perhaps using IAuthorizationRequirement, as described here. It allows you to create very flexible authorization rules.