Login in Prism WPF application

Question

I’m developing a WPF application using PRISM and I need to implement a Login functionality that loads before the Shell.

1. What is the best way to do it? Treat the login as a module? Put it in the main project altogether with the Shell?

2. If the login is correct, I need to store some user information (name, role, etc.) to use it later across the application (in the Shell and also in modules). Where and how should I store this information?

Thanks in advance.

Answer 1

This discussion describes a solution to showing the login form before the shell: http://compositewpf.codeplex.com/discussions/29570

As to how to store the user's details, you could utilise the .Net GenericPrincipal and GenericIdentity classes. They let you represent "basic" information about a user, such as their username and roles. The principal/identity can then be stored against the current thread, so you don't need to worry about creating some kind of static/singleton class through which to access the details. It also becomes easy to check the current user's role membership.

Create the objects and assign to the current thread like this:-

string[] roles = { "User", "Admin" };
Thread.CurrentPrincipal = new GenericPrincipal(
    new GenericIdentity("Joe"),
    roles);

Then whenever you want to access details of the currently logged-in user:-

public string GetUsername()
{
    var principal = Thread.CurrentPrincipal;
    var identity = principal == null ? null : principal.Identity;
    return identity == null ? null : identity.Name;
}

public bool IsInRole(string role)
{
    var principal = Thread.CurrentPrincipal;
    return principal == null ? false : principal.IsInRole(role);
}

If GenericPrincipal and GenericIdentity aren't suitable, I would create a singleton class with the necessary properties (name, roles, etc) that can be passed around to other parts of the application, e.g. using an IoC container. A static class is an even easier solution (no need to pass around), but statics can make unit testing more tricky.