Question

我有一个表单，用户可以在其中编辑其用户帐户信息，然后保存新的更改。

当我将修改后的更改保存到数据库时，我遇到了问题。

在行context.SaveChanges（）上，我抛出了DbUpdateConcurrencyException异常。它说，"Store update, insert, or delete statement affected an unexpected number of rows (0). Entities may have been modified or deleted since entities were loaded. Refresh ObjectStateManager entries.“

我不知道为什么。

这就是我所做的：

public ActionResult EditUserAccount()
{
    UserAccountViewModel editUserAccountViewModel = new UserAccountViewModel();
    editUserAccountViewModel.UserName = UserSession.GetValue(StateNameEnum.UserName, StateNameEnum.UserName.ToString()) as string;
    int UserId = WebSecurity.GetUserId(editUserAccountViewModel.UserName);
    var userInfo = context.db_user.First(x => x.UserId == UserId);

    editUserAccountViewModel.Title = userInfo.Title;
    editUserAccountViewModel.FirstName = userInfo.FirstName;
    editUserAccountViewModel.LastName = userInfo.LastName;
    editUserAccountViewModel.PhoneNumber = userInfo.PhoneNumber;
    editUserAccountViewModel.AltPhoneNumber = userInfo.AltPhoneNumber;
    editUserAccountViewModel.EmailAddress = userInfo.EmailAddress;
    editUserAccountViewModel.UserAccountState = UserAccountViewModel.AccountState.EDIT;
    return (PartialView("~/Views/Account/UserAccount.cshtml", editUserAccountViewModel));

}

[HttpPost]
public ActionResult EditUserAccount_Save(UserAccountViewModel editUserAccountViewModel)
{
    try
    {
        if (ModelState.IsValid)
        {
            editUserAccountViewModel.UserName = UserSession.GetValue(StateNameEnum.UserName, StateNameEnum.UserName.ToString()) as string;

            db_user user = new db_user();
            user.Title = editUserAccountViewModel.Title;
            user.FirstName = editUserAccountViewModel.FirstName;
            user.LastName = editUserAccountViewModel.LastName;
            user.PhoneNumber = editUserAccountViewModel.PhoneNumber;
            user.AltPhoneNumber = editUserAccountViewModel.AltPhoneNumber;
            user.EmailAddress = editUserAccountViewModel.EmailAddress;
            user.LanguageId = context.languages.Where(t => t.Code == editUserAccountViewModel.Language).Select(t => t.Id).SingleOrDefault();
            user.CreatedDate = DateTime.Now;
            user.UserId = WebSecurity.GetUserId(editUserAccountViewModel.UserName);

            context.Entry(user).State = EntityState.Modified;
            context.SaveChanges();

            JsonResult res = Json(new { Success = true, data = "", Message = "" });
            return res;
        }
        else
        {
            JsonResult res2 = Json(new { Success = false, data = "", Message = "" });
            return res2;
        }
    }
    return null;
}

Answer 1

您没有在控制器操作中创建context的实例，这意味着它处于类级别。这意味着context与该控制器处理的每个其他Web请求共享。这部分错误消息Entities may have been modified or deleted since entities were loaded似乎证实了这一假设。

而是在控制器操作中创建context的实例。

由于您在此操作中编辑现有用户，因此首先需要将现有用户从数据库加载到context，而不是像现在一样实例化新用户。

我强烈怀疑此更改将解决您的问题。

<强>更新

这是一个代码示例。我不知道你的上下文类被调用了什么，所以你可能不得不改变那个部分。我假设调用此控制器时用户必须已存在（基于方法名称）。我删除了try，因为你没有抓到任何东西。如果在抛出异常时可以执行某些有用的操作，请继续将其重新放入。

[HttpPost]
public ActionResult EditUserAccount_Save(UserAccountViewModel editUserAccountViewModel)
{
    if (ModelState.IsValid)
    {
        using (MyContext context = new MyContext())
        {
            int userId = WebSecurity.GetUserId(editUserAccountViewModel.UserName);
            db_user user = context.DbUsers.Where(u => u.Id == userId).Single();
            editUserAccountViewModel.UserName = UserSession.GetValue(StateNameEnum.UserName, StateNameEnum.UserName.ToString()) as string;

            user.Title = editUserAccountViewModel.Title;
            user.FirstName = editUserAccountViewModel.FirstName;
            user.LastName = editUserAccountViewModel.LastName;
            user.PhoneNumber = editUserAccountViewModel.PhoneNumber;
            user.AltPhoneNumber = editUserAccountViewModel.AltPhoneNumber;
            user.EmailAddress = editUserAccountViewModel.EmailAddress;
            user.LanguageId = context.languages.Where(t => t.Code == editUserAccountViewModel.Language).Select(t => t.Id).SingleOrDefault();
            user.CreatedDate = DateTime.Now;

            context.SaveChanges();

            JsonResult res = Json(new { Success = true, data = "", Message = "" });
            return res;
        }
    }
    else
    {
        JsonResult res2 = Json(new { Success = false, data = "", Message = "" });
        return res2;
    }
}

保存对用户帐户的更改会导致DbUpdateConcurrencyException

1 个答案: