ASP.net MVC - Should I use AutoMapper from ViewModel to Entity Framework entities?

Question

I am currently using AutoMapper to map my Entity Framework entities to my View Model:

public class ProductsController : Controller {     private IProductRepository productRepository;      public ProductsController(IProductRepository productRepository)     {          this.productRepository = productRepository;     }      public ActionResult Details(int id)     {         var product = productRepository.GetProduct(id);          if( product == null )             return View("NotFound");          ProductDetailsViewModel model = Mapper.Map<Product, ProductDetailsViewModel>(product);          return View(model);     } } 

This works well. The question I have is when I need to go from my View Model to my entity in order to update the database. Should I be using AutoMapper for this? Is this a bad/dangerous practice?

It seems like AutoMapper is good for flattening a complex type to a simple (flat) type, but so far I'm struggling trying to go from a flat/simple to a more complex type like my entity with the various navigation properties.

If it is a bad idea to use AutoMapper to do this, then what would my code look like for a Create action?

public ActionResult Create(CreateProductViewModel model) {     if( ModelState.IsValid )     {         // what do i do here to create my Product entity?     } } 

What about an Edit action?

public ActionResult Edit(int id, EditProductViewModel model) {     Product product = productRepository.GetProduct(id);      // how do i convert my view model to my entity at this point??? } 

Answer 1

I'm a of the mindset that updating your entities is a pretty big deal and that no automated tool should ever be used. Set the properties manually.

Yes its a very tiny amount of more code but automapper or running updatemodel on database entities can sometimes have unintended consequences. Better to make sure your writes are done correctly.