Some Basical Questions About MVVM Pattern

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Hi Guys
I've studying the nice MVVM pattern and going to use it in my application.
But I've found some obscurer thing which i need to somebody make them clear for me:

1-what is the benefit of using Action in RelayCommand Class?
2-Why the Validation Applied in the Model Class instead Of ViewModel Classes?

wait Your valuable answers,
Thanks indeed my dear Friends.

Posted 15-Jun-12 20:10pm

IT-discovery

Updated 15-Jun-12 20:12pm

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Abhinav S · Answer 1 · 2012-06-15T20:20:00

Solution 1

Why the Validation Applied in the Model Class instead Of ViewModel Classes?

This is the classes that handles data.
This is also the class that has INotifyProperty implemented. So it makes sense to have validations here.

However, there is nothing stopping you from implementing validations in the view model as well.

IMO, there is no one rule or the other, just choose a way you are comfortable with.

Posted 15-Jun-12 20:20pm

Abhinav S

Comments

SteveAdey 20-Jun-12 16:40pm

I sincerely hope you don't have INotifyProperty on your model. The model should be light weight and free from knowing anything about business logic or property changes. Validation should be done with a separate class or service that is used by the view model. That service will use the model in its validation, but at no stage should the validation logic be inside the model. This will hamper reuse.

IT-discovery · Answer 2 · 2012-06-16T02:18:00

Solution 2

thanks abhinav,
so whats about Using the ACTION?

Posted 16-Jun-12 2:18am

IT-discovery