How to map View Model back to Domain Model in a POST action?

Question

Every article found in the Internet on using ViewModels and utilizing Automapper gives the guidelines of the \"Controller -> View\" direction mapping. You take a domain mod

Answer 1

Tools like AutoMapper can be used to update existing object with data from source object. The controller action for updating might look like:

[HttpPost]
public ActionResult Update(MyViewModel viewModel)
{
    MyDataModel dataModel = this.DataRepository.GetMyData(viewModel.Id);
    Mapper(viewModel, dataModel);
    this.Repostitory.SaveMyData(dataModel);
    return View(viewModel);
}

Apart from what is visible in the snippet above:

• POST data to view model + validation is done in ModelBinder (could be exended with custom bindings)
• Error handling (i.e. catching data access exception throws by Repository) can be done by [HandleError] filter

Controller action is pretty thin and concerns are separated: mapping issues are addressed in AutoMapper configuration, validation is done by ModelBinder and data access by Repository.