I'm continuing to learn WPF, and focusing on MVVM at the moment and using Karl Shifflett’s "MVVM In a Box" tutorial. But have a question about sharing data between views/viewmodels and how it updates the view on the screen. p.s. I haven't covered IOC's yet.
Below is a screenshot of my MainWindow in a test application. Its split into 3 sections (views), a header, a slide panel with buttons, and the remainder as the main view of the application. The purpose of the application is simple, login to the application. On a successful login, the login view should disappear by it being replaced by a new view (i.e. OverviewScreenView), and relevant buttons on the slide of the application should become visible.
I see the application as having 2 ViewModels. One for the MainWindowView and one for the LoginView, given the MainWindow doesn't need to have commands for Login so i kept it separate.
As i haven't covered IOC's yet, I created a LoginModel class which is a singleton. It only contains one property which is "public bool LoggedIn", and an event called UserLoggedIn.
The MainWindowViewModel constructor registers to the event UserLoggedIn. Now in the LoginView , when a user clicks Login on the LoginView, it raises a command on the LoginViewModel, which in turn if a username and password is correctly entered will call the LoginModel and set LoggedIn to true. This causes the UserLoggedIn event to fire, which is handled in the MainWindowViewModel to cause the view to hide the LoginView and replace it with a different view i.e. an overview screen.
Questions
Q1. Obvious question, is logging in like this a correct use of MVVM. i.e. Flow of control is as follows. LoginView --> LoginViewViewModel --> LoginModel --> MainWindowViewModel --> MainWindowView.
Q2. Assuming the user has logged in, and the MainWindowViewModel has handled the event.