CODEWITHSUNDEEP
asp.net-mvcmvvm
Walt
Walt

Reputation: 1531

Confused about .net MVC View Models and Models

So, I've read a bit about .net and MVC. I remember reading something that suggested using ViewModels in MVC. This would help lessen the desire to have the view messing with data that should be controlled by the controller.

I thought this is what is referred to by the MVVM pattern. Evidently after looking at that, the implementation actually does away with controllers altogether. Not exactly what I want to do.

Is it still legit to use a ViewModel in my case? Is it better practice or just unnecessary work? Where would you put your ViewModels directory/namespace at? Under the Models directory?

Is it legit for Models to know about ViewModels? For example, you have a Model Return a ViewModel to the controller?

Upvotes: 1

Views: 3362

Answers (3)

user1231623
user1231623

Reputation:

ViewModels are not by default in MVC projects. It is something you need to add if you feel it benefits you to couple View to a Model "easier"

http://rachelappel.com/use-viewmodels-to-manage-data-amp-organize-code-in-asp.net-mvc-applications

The concept of the ViewModel isn't just for ASP.NET MVC, as you'll see references to ViewModels throughout the web in articles and blog posts about the MVC, MVP, and MVVM patterns. Those posts and articles can center around any number of technologies such as ASP.NET, Silverlight, WPF, or MVC... This post will investigate ViewModels as they apply to the world of ASP.NET MVC.

http://msdn.microsoft.com/en-us/magazine/ff798279.aspx

Upvotes: 2

Tom Stickel
Tom Stickel

Reputation: 20401

Models and ViewModels are different. Don't confuse the ViewModel with the MVVM pattern.

The use of a view model can make the interaction between model and view more simple. A model can sometimes be over complicated having other model objects as members, which could have model objects as member etc..

By using a view model you have a good way to simplify what the view deals with. This will also filter down what can be seen in intellisense, so if you have different people developing the models than those working on the views, creating a simple view model can make it much easier for those just dealing with the UI.

Upvotes: 1

Bojin Li
Bojin Li

Reputation: 5789

Design patterns in my opinion are not rigid concepts, but rather guidelines that help you architect your application better. The Model-View-ViewModel(MVVM) design pattern stems from WPF, where there is a very robust Bata Binding framework that facilitated the pattern. The idea is that you have business data in your model, but since there are often view specific data(i.e the currently selected item in a tree control) that didn't belong in the model, you created view model objects that wraps your model, but the view models also contained view specific state data. So your views can bind to the view models instead of the model objects directly, thus keeping the models clean(easy to test, maintain etc).

Asp.net MVC is different in that the databinding in the Views is nowhere near as powerful as it is in WPF. In WPF you could actually implement much of your GUI and model data interaction through databinding, which made the view models useful. But in Asp.net MVC your controllers are designed to handle this, and since the databinding is close to non existant I just don't see the value of having view model wrappers around your model objects in Asp.net MVC.

Upvotes: 1

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