Question

I use ASP.NET MVC3 and as Data layer LinqToSql.
I`m a little bit confuse how can i edit an entity.

public ActionResult Edit(int id)
{
    var product = _repository.GetById(id);
    return View(product);
}


[HttpPost]
public ActionResult Edit(Product product)
{
    if (ModelState.IsValid)
    {
        _repository.EditProduct(product);
        return RedirectToAction("Index");
    }
    return View();
}

Variable product in Edit() is ok, but after editing view the variable passed in [HttpPost] Edit
has null in link properties and seems to be detached from my DataContext.
And also what code should i execute in EditProduct method to update entity?

Thanks.

Answer 1

I am assuming in your repository you have an object for your data context. In your EditProduct call you should have something like:

Product prod = dataContext.Products.Single(p=>p.ProductID == product.ProductID);

prod.PropertyA = product.PropertyA;
prod.PropertyB = product.PropertyB;
dataContext.SubmitChanges();

You can also attach the product coming in and save (if you have a timestamp column):

dataContext.Products.Attach(product,true);
dataContext.SubmitChanges();

If you don’t have a timestamp column then L2S will throw an error about not being able to check it’s state.

An entity can only be attached as modified without original state if it declares a version member or does not have an update check policy.

If you add a timestamp column to your DB then L2S can do the above.

Here’s a deeper explanation.