Mvvm model to viewmodel communication

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In MVVM I can clearly understand communication between View and ViewModel using INotifyPropertyChanged and Commands.

But what about ViewModel to Model communication and vice versa. For me it is unclear what approach is best for MVVM architecture.

Should I just call Model methods from ViewModel directly? And how I shoud track changes in Model - any standart approach?

There is rly little information about Model to ViewModel communication

What I have tried:

Right now I'm just directly calling Model methods from ViewModel. Tried to implement INotifyPropertyChanged on Model but that feels messy

Posted 5-Mar-18 10:06am

Member 13710242

Updated 6-Mar-18 0:12am

TheRealSteveJudge

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TheRealSteveJudge · Answer 1 · 2018-03-05T23:55:00

There is nothing wrong in calling directly methods of the Model from the ViewModel.
But the Model shall have no knowledge of the ViewModel.

In order to receive events from the model without breaking the MVVM principle
you could use a so-called Event Aggregator as described here:

Using the Event Aggregator Pattern to Communicate Between View Models - TechNet Articles - United States (English) - TechNet Wiki[^]

#realJSOP · Answer 2 · 2018-03-05T23:50:00

The model does nothing more than get/save/or delete data from the data source. The view should never directly call any method or refer to any property in the model.

There are many ways to manage this interaction, but presenting a reasonably complete example in Q/A is beyond the intent of Q/A.

Try this youtube lesson:

C# WPF UI Tutorials: 03 - View Model MVVM Basics - YouTube[^]

Mvvm model to viewmodel communication

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