Question

I am learning MVC3 and EF4.1 . I am currently experimenting with Database first EF with the new the TT4 generator to generate lean data classes. I have generated a CRUD controller, and have come across the issue of how best to display DB constraint messages in the View.

My code is so far:

    [HttpPost]
    public ActionResult Delete(Guid id, aspnet_Users User)
    {
        string errorMessage = string.Empty;
        try
        {
            // TODO: Add delete logic here
            db.Entry(User).State = System.Data.EntityState.Deleted;
            db.SaveChanges();
            return RedirectToAction("Index");
        }
        catch(Exception err)
        {
            return Content(err.InnerException.StackTrace);
            //return View();
        }
    }

Any help greatly appreciated.

Ed

Answer 1

One of the simplest things to do is add a model error with the exception message. This essentially treats the constraint violation as a validation error. You should probably customize the message for the user, however.

[HttpPost]
public ActionResult Delete(Guid id, aspnet_Users User)
{
    try
    {
        // TODO: Add delete logic here
        db.Entry(User).State = System.Data.EntityState.Deleted;
        db.SaveChanges();
        return RedirectToAction("Index");
    }
    catch(Exception err)
    {
        ModelState.AddModelError(String.Empty, err.Message);
        return View(User);
    }
}