保存對用戶帳戶的更改導致DbUpdateConcurrencyException

Question

我有一個表單，用戶可以編輯其用戶帳戶信息，然後保存新的更改。

當我將修改後的更改保存到數據庫時，我遇到了問題。

上線context.SaveChanges（），我得到一個DbUpdateConcurrencyException異常拋出。它說，"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.「

我不知道爲什麼

這裏是我做了什麼：

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

你是不是在控制器動作中創建的context一個實例，這將意味着它這意味着context與該控制器處理的每個其他Web請求共享，這部分錯誤消息Entities may have been modified or deleted since entities were loaded似乎證實了該假設。而是在您的控制器操作中創建context的實例。

由於您正在編輯此操作中的現有用戶，因此首先需要將現有用戶從數據庫加載到context，而不是像現在這樣實例化新用戶。

我強烈懷疑此更改將解決您的問題。

UPDATE

下面是一個代碼示例。我不知道你的上下文類是什麼，所以你可能不得不改變那部分。我假定當調用這個控制器時（基於方法的名稱），用戶必須已經存在。我刪除了try，因爲你沒有捕捉任何東西。如果有用，你可以做的時候拋出一個異常的東西，繼續前進，擺在那了。

[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; 
    } 
}