Question

This query is about MVC design pattern in general and not ASP.net MVC framework

I understand in MVC (desktop application):

1. User clicks something in view
2. this is passed on to controller to manage
3. controller makes some changes in Model
4. Model calls method on view which has the logic to refresh UI

Questions around these:

Q1) Can controller also modify View or Model only updates View?

Q2) When screen loads for the first time, there is no Model change. Then, who fetches data from model and populates view? View directly calls Model and populates itself OR controller gets data and passes to view method OR some dummy event is raised at Model which updates View?

Answer 1

From model-view-controller :

1. The user interacts with the user interface in some way. (for example, presses a mouse button).
2. The controller handles the input event from the user interface, often via a registered handler or callback and converts the event into appropriate user action, understandable for the model.
3. The controller notifies the model of the user action, possibly resulting in a change in the model’s state. (For example, the controller updates the user’s shopping cart.)
4. A view queries the model in order to generate an appropriate user interface (for example, the view lists the shopping cart’s contents). The view gets its own data from the model. In some implementations, the controller may issue a general instruction to the view to render itself. In others, the view is automatically notified by the model of changes in state (Observer) that require a screen update.
5. The user interface waits for further user interactions, which restarts the control flow cycle.