我收到'System.Data.Entity.Infrastructure.DbUpdateConcurrencyException' .....当我尝试更新表中的一行时

Question

我正在尝试更新表中的特定行，但我得到了 EntityFramework.dll 中出现“System.Data.Entity.Infrastructure.DbUpdateConcurrencyException”类型的异常，但未在用户代码中处理

{“存储更新、插入或删除语句影响了意外数量的行 (0)。实体可能在加载实体后已被修改或删除。有关理解和处理乐观并发异常的信息，请参阅 http://go.microsoft.com/fwlink/?LinkId=472540。” }

我的动作方法是

 public ActionResult createedit()
    {
        int id = Convert.ToInt32( Session["UserID"]);
        var Certtt = (from cert in db.TBL_UserRegistration where cert.UserLoginID == id select cert).FirstOrDefault();


        TBL_UserRegistration u = db.TBL_UserRegistration.Find(Certtt.UserRegistrationID);
        return View(u);

    }
    [HttpPost]
    public ActionResult createedit(TBL_UserRegistration user, HttpPostedFileBase imageup)
    {



            if(imageup != null)
            {
                user.UserImage = new byte[imageup.ContentLength];
                imageup.InputStream.Read(user.UserImage, 0, imageup.ContentLength);
            }
            db.Entry(user).State = EntityState.Modified;
            db.SaveChanges();


        return View(user);

    }

我的看法

  @using (Html.BeginForm("createedit", "UserRegistration", FormMethod.Post, new { enctype = "multipart/form-data" }))
        {
            @Html.AntiForgeryToken()

            <form class="wiwet-checkout">
                <div class="row">
                    <div class="col-sm-6">
                        <!-- <input type="text" placeholder="First Name" />-->
                        @*@Html.LabelFor(model => model.UserFirstName, htmlAttributes: new { @class = "text-label", @placeholder = "Password" })*@
                        @Html.EditorFor(model => model.UserFirstName, new { htmlAttributes = new { @class = "form-control", @placeholder = "First Name" } })
                        @Html.ValidationMessageFor(model => model.UserFirstName, "")
                    </div>
 .
 .
 .
 }

我的模型 TBL_UserResgistration 是

public partial class TBL_UserRegistration
{
    public TBL_UserRegistration()
    {
        this.TBL_Payment = new HashSet<TBL_Payment>();
    }

    public int UserRegistrationID { get; set; }
    public Nullable<System.DateTime> UserRegistrationDate { get; set; }
    public string Username { get; set; }
    public string UserPassword { get; set; }
    public string UserFirstName { get; set; }
    public string UserLastName { get; set; }
    public string UserEmail { get; set; }
    public string UserType { get; set; }
    public string UserCity { get; set; }
    public string UserState { get; set; }
    public string UserCountry { get; set; }
    public Nullable<int> UserZip { get; set; }
    public string UserAddressLine1 { get; set; }
    public string UserAdressLine2 { get; set; }
    public Nullable<long> UserPhone1 { get; set; }
    public Nullable<long> UserPhone2 { get; set; }
    public byte[] UserImage { get; set; }
    public Nullable<int> UserLoginID { get; set; }

    public virtual TBL_Login TBL_Login { get; set; }
    public virtual ICollection<TBL_Payment> TBL_Payment { get; set; }
}

Answer 1

您收到此异常是因为实体框架无法在数据库中找到您的用户对象来更新它READ MORE，那是因为您正在传递一个只有名字的用户实体，正如我从您的视图中看到的那样，您可以这样做，将您的 id 作为隐藏字段传递，从您的数据库上下文中通过 id 获取用户模型，设置新用户的名字，更新，完成。 这就是你的做法

在您看来，将 id 作为隐藏传递

  @using (Html.BeginForm("createedit", "UserRegistration", FormMethod.Post, new { enctype = "multipart/form-data" }))
        {
            @Html.AntiForgeryToken()
            <!-- here is the hidden field keeping your id --> 
            @Html.Hidden("UserRegistrationID ",Model.UserRegistrationID )
            <form class="wiwet-checkout">
                <div class="row">
                    <div class="col-sm-6">
                        <!-- <input type="text" placeholder="First Name" />-->
                        @*@Html.LabelFor(model => model.UserFirstName, htmlAttributes: new { @class = "text-label", @placeholder = "Password" })*@
                        @Html.EditorFor(model => model.UserFirstName, new { htmlAttributes = new { @class = "form-control", @placeholder = "First Name" } })
                        @Html.ValidationMessageFor(model => model.UserFirstName, "")
                    </div>
 .
 .
 .
 }

在你的控制器中

// get the real entity from the database using the id passed to your controller
// as i mentioned before you should keep it in a hidden field 
TBL_UserRegistration u = db.TBL_UserRegistration.Find(user.UserRegistrationID);
// update the entity user name according to the new one passed from your view 
u.UserFirstName  = user.UserFirstName; 
// update    and save 
db.Entry(u).State = EntityState.Modified;
db.SaveChanges();