Fetching data within an ASP.NET MVC ViewModel class?

Question

For those that create ViewModels (for use by typed views) in ASP.NET MVC, do you prefer to fetch the data from a service/repository from within the ViewModel, or the controller

Answer 1

I encountered the same issue. I started creating classes for each action when the code got too big for the action methods. Yes you will have some data retrieval in classes and some in the controller methods. The alternative is to have all the data retrieval in classes, but half the classes you won't really need, they will have been created for consistency sake or have all the data retrieval in the controller methods, but again, some of those methods will be too complex and needed to have been abstracted into classes... so pick your poison. I would rather have a little inconsistency and have the right solution for the job.

As for putting behavior into the ViewModel, I don't, the point of the ViewModel is to be a thin class for setting and extracting values from the View.

There have been cases where I've put conversion methods in the ViewModel. For instance I need to convert the ViewModel to the corresponding entity or I need to load the ViewModel with data from the Entity.

To answer your question, I prefer to retrieve data from with in the controller/action methods.

Typically with DropDowns, I create a dropdown service. DropDowns tend to be the same data that spans views. With the dropdowns in a service I can use them on other views and/or Cache them.

Depending on the layout, 40 plus fields could create a cluttered view. Depending the type of data, I would try to span that many fields across multiple views with some sort of tabbed or wizard interface.