Save data in state-machine

Question

what is the best way to save data in a state-machine-like application?

How the application works:

There are multiple states, like Loging, MainMenu, Registration, etc. There is a loop that working until the state reaches Exit.

while(currentState != States.Exit)
{
   switch (currentState)
   { 
      case Login:
            // Do everything needed for the login, including showing the Login-Window.
            LoginProcess();
         break;
      case MainMenu:
            MainMenuProcess();
         break;
      // Etc...
   }
}

The problem:

I want to save data in between these processes. For example I want to have a User Object after the login containing everything that has to do with the user. There are many variables I could have to save and they are not always initialized (i.e. the User can only exist after login).

How it's done until now:

Right now there are just "public" members that can be null if the respective process has not started. They are defined in the class of the State-Machine loop. This can get messy easily.

Expectations:

I would like to have a way to do this data-saving in a clean way. Maybe even extract it from the state-machine or something similar. Maybe there is a way to restrict processes to access members they should not change?

Thanks in advance.

Answer 1

You could persist it to a database, or serialize your model into a JSON object, this object could be saved, then loaded up later and deserialized into your domain model.

You can also consider sagas, there are frameworks that support the notion of this and might help solve the problem. http://www.cs.cornell.edu/andru/cs711/2002fa/reading/sagas.pdf