Using AutoMapper in the Edit action method in an MVC3 application

Question

Here is my controller code, which works 100% as I need it to. However the POST method isn't using the AutoMapper and that is not OK. How can I use AutoMapper in this action method?

I'm using Entity Framework 4 with the Repository Pattern to access data.

public ActionResult Edit(int id)
{
    Product product = _productRepository.FindProduct(id);
    var model = Mapper.Map<Product, ProductModel>(product);
    return View(model);
}

[HttpPost]
public ActionResult Edit(ProductModel model)
{
    if (ModelState.IsValid)
    {
        Product product = _productRepository.FindProduct(model.ProductId);

        product.Name = model.Name;
        product.Description = model.Description;
        product.UnitPrice = model.UnitPrice;

        _productRepository.SaveChanges();

        return RedirectToAction("Index");
    }

    return View(model);
}

If I use AutoMapper, the entity framework reference is lost and the data doesn't persist to the database.

[HttpPost]
public ActionResult Edit(ProductModel model)
{
    if (ModelState.IsValid)
    {
        Product product = _productRepository.FindProduct(model.ProductId);
        product = Mapper.Map<ProductModel, Product>(model);

        _productRepository.SaveChanges();

        return RedirectToAction("Index");
    }

    return View(model);
}

I'm guessing this is caused the Mapper.Map function returning a brand new Product object and because of that, no references to the entity framework graph is being kept. What alternatives do you suggest?

Answer 1

I think you just do

 Product product = _productRepository.FindProduct(model.ProductId);
 Mapper.Map(model, product);
 _productRepository.SaveChanges();

you may also want to check that you have a non null product first, and also that user is allowed to change that product....