How to update a record in database in Entity Framework?

Question

I'm using c# mvc with EF and i'm building a website. When i'm updating a table with new values it gives the following error.

{"Violation of PRIMARY KEY constraint 'PK_Table_1_1'. Cannot insert duplicate key in object 'dbo.User'. The duplicate key value is ([email protected]).\r\nThe statement has been terminated."}

Here is my design of the table.

Here is my controller file

[HttpPost]
    public ActionResult Manage(ManageViewModel manageviewmodel)
    {
        TheFoodyContext db = new TheFoodyContext();
        string UserEmail = Session["UserEmail"].ToString();
        User user_to_update = db.Users.Find(UserEmail);

        if (ModelState.IsValid)
        {

            try
            {
                HttpPostedFileBase photo = Request.Files["photo"];

            if (photo != null && photo.ContentLength > 0)
            {
                var path = "";
                var fileName = Path.GetFileName(photo.FileName);
                var extension = Path.GetExtension(photo.FileName);
                var allowedExtensions = new[] {".Jpg", ".png", ".jpg", "jpeg"};
                if (allowedExtensions.Contains(extension))
                {
                    string name = Path.GetFileNameWithoutExtension(fileName);
                    string myfile = name + "_" + UserEmail + extension;
                    path= Path.Combine(Server.MapPath("~/Img"), myfile);
                    photo.SaveAs(path);
                    user_to_update.photo = myfile;

                }
                else
                {
                    ViewBag.message = "Please choose only Image file";
                }


                user_to_update.email = UserEmail;
                user_to_update.fname = manageviewmodel.FirstName;
                user_to_update.lname = manageviewmodel.LastName;
                user_to_update.phone = manageviewmodel.Phone;
                user_to_update.address = manageviewmodel.Address;
                user_to_update.city = manageviewmodel.City;
                user_to_update.postcode = Convert.ToDecimal(manageviewmodel.PostCode);
                user_to_update.district = manageviewmodel.District;
                user_to_update.user_type = manageviewmodel.UserType;
                user_to_update.status = manageviewmodel.Status;
                user_to_update.photo = path;

                db.Users.Add(user_to_update);
                db.SaveChanges();

                Session["UserEmail"] = UserEmail;
                Session["FirstName"] = manageviewmodel.FirstName;
                Session["LastName"] = manageviewmodel.LastName;
                Session["Address"] = manageviewmodel.Address;
                Session["City"] = manageviewmodel.City;
                Session["PostCode"] = manageviewmodel.PostCode;
                Session["District"] = manageviewmodel.District;
                Session["UserType"] = manageviewmodel.UserType;
                Session["Status"] = manageviewmodel.Status;
                Session["Phone"] = manageviewmodel.Phone;
                return RedirectToAction("Manage");
            }
            }
            catch (Exception ex)
            {
             return View(ex.Message);
            }
            return View(manageviewmodel);
            }

            return View(manageviewmodel);

        }

Here is my Model file

public class ManageViewModel
{
    public string FirstName { get; set; }
    public string LastName { get; set; }
    public string Email { get; set; }
    public string Phone { get; set; }
    public string photo { get; set; }
    public string Address { get; set; }
    public string City { get; set; }
    public int PostCode { get; set; }
    public string District { get; set; }
    public string UserType { get; set; }
    public string Status { get; set; }
}

Manfred Radlwimmer · Accepted Answer · 2016-11-04 12:04:04Z

5

You don't need to add the user again (it already exists and EF tracks changes), simply call SaveChanges and you are done.
Just remove this line:

db.Users.Add(user_to_update);

and it should work (unless there are more errors).

answered Nov 4, 2016 at 12:04

Manfred Radlwimmer

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2 Comments

Marco Over a year ago

Why the downvote? You can't add an entity which already exists. It would have the same key and eplain the OPs exception

Punya Munasinghe Over a year ago

@Manfred Radlwimmer Thank you so much. It worked like a charm. :)

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