MVVM Structure for app

Question

Good day,
I'm starting with MVVM patter for my app. I would like to learn this by re-creating my old app (vb.net winforms). I know that I need model, viewmodel and view and I understand what for. I'm trying to create a mvvm structure for my app and I'm lost a little
bit. My app has few levels - User - Admin - FPOC (first point of contact). User is able to save records to the database and retrieve it, Admin is able to review all the records and FPOC is able to review and change all of them. What I would like to understand
here is - should I create for e.g. Class Library for each profile and create model and viemodel there and call it from main view or should I create a folders and prepare classes for each profile in one project? All profiles are using SQL database connection
to obtain datab from the tables.
There are many examples but, most of them are based only on Person/Customer and I have no idea how could I create structure for my application.
Thank you for suggestions

Answer 1

MVVM is a UI desing pattern and it should not affect the structure of your domain or business objects in any way. All domain/business logic belongs to the model.
The logic of saving and retrieving data should be encapsulated in a data access library (class library) and should not have any dependencies whatsoever upon any view model or view.
If you want to learn how to restructure an application that was written in "traditional" way with event-handlers in the code-behind to an MVVM application there is a video available here:
http://blog.lab49.com/archives/2650.
>>What I would like to understand here is - should I create for e.g. Class Library for each profile and create model and viemodel there and call it from main view or should I create a folders and prepare classes for each profile in one project?
The model and view model classes generally don't belong in the same class library. A model class shouldn't know anything about a view model. You could define your model classes in a separate class library and then add a reference to this class library from
the project in which you define the view model classes. Keep your data access logic in the model project, or better yet in a DAL (data access library) that may be referenced from the model library.
Hope that helps.
Please remember to close your threads by marking helpful posts as answer and then start a new thread if you have a new question.